Ng Hien Cu u Java Mobile

8/2/2019 Ng Hien Cu u Java Mobile

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TRNG I HC KHOA HC TNHINKHOA CNG NGH THNG TIN

B MN MNG MY TNH VIN THNG

NG NGUYN KIM ANH O ANH TUN

NGHIN CU JAVA MOBILEV XY DNG NG DNG

MINH HA

KHA LUN CNHN TIN HC

TP.HCM, 2005


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Li Cm n!

Sau hn nm thng tm hiu v thc hin, lun vn Nghin cu cng nghJava Mobile v xy dng ng dng minh ho cbn hon thnh. t c

kt qu ny, chng ti n lc ht sc ng thi cng nhn c rt nhiu s

quan tm, gip , ng h ca cc thy c, bn b v gia nh.

Trc ht, chng em xin gi li cm n chn thnh n B mn Mng my

tnh v Vin thng, Khoa Cng ngh Thng tin, trng i hc Khoa hc T nhin

v cc thy c c bit l Thy Nguyn Minh Tun tn tnh gip , hng dn

chng em hon thnh lun vn ny.

Chng ti rt cm n cc bn b trong khoa, cc anh ch, cc bn trong cng

ng Java Vit Nam bn cnh ng h, ng gp kin cho chng ti trong qu

trnh thc hin lun vn.

V chng con cng xin chn thnh cm n gia nh lun ng vin, to

iu kin tt nht cho chng con hc tp v hon tt lun vn.

Lun vn hon thnh vi mt s kt qu nht nh, tuy nhin vn khng

trnh khi sai st. Knh mong s cm thng v ng gp kin t cc thy c v

cc bn.

Thnh ph H Ch Minh, thng 7 nm 2005

ng Nguyn Kim Anh - o Anh Tun


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MC LC

Li Ni u...................................................................................................... 1Phn 1: Kin thc nn tng J2ME ................................................................ 5Chng 1: Tng quan v J2ME.................................................................... 5

1.1 Gii thiu J2ME (Java 2 Micro Edition).......................................................51.2 L do chng ta cn J2ME..............................................................................61.3 Cc thnh phn ca J2ME:............................................................................7

1.3.1Configuration:.............................................................................................71.3.2Profile: ........................................................................................................91.3.3My o Java ..............................................................................................10

Chng 2: Gii thiu CLDC v MIDP ...................................................... 132.1. CLDC ..........................................................................................................13

2.1.1.Yu cu phn cng: ..................................................................................132.1.2.Yu cu phn mm: ..................................................................................132.1.3.My o Java:.............................................................................................13

2.2. MIDP:..........................................................................................................162.2.1.Yu cu phn cng: ..................................................................................162.2.2.Yu cu phn mm: ..................................................................................162.2.3.Cu trc MID Profile:...............................................................................162.2.4.MIDlet Suite: ............................................................................................182.2.5.Mi trng pht trin ng dng J2ME.....................................................22

Chng 3: Cc vn cbn ca chng trnh MIDlet......................... 25

3.1. Cu trc cbn: ..........................................................................................253.2. Xy dng mt ng dng MIDlet:................................................................253.3. Lp MIDlet: ................................................................................................263.4. Lp MIDletStateChangeException: ............................................................283.5. Display.........................................................................................................283.6. Lp Displayable: .........................................................................................303.7. Qun l cc s kin (event).........................................................................32

3.7.1.Command & CommandListener...............................................................333.7.2.Item v ItemStateListener.........................................................................38

Chng 4: Giao din ha cp cao.......................................................... 40

4.1. Screen: .........................................................................................................424.2. Form: ...........................................................................................................434.3. Item:.............................................................................................................45

4.3.1.DateField: .................................................................................................464.3.2.Gauge:.......................................................................................................484.3.3.String Item:...............................................................................................514.3.4.TextField: .................................................................................................534.3.5.ChoiceGroup: ...........................................................................................574.3.6.Image v ImageItem:................................................................................61

4.4. List:..............................................................................................................64


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4.5. TextBox: ......................................................................................................694.6. Alert v AlertType: .....................................................................................72

4.6.1.Alert: .........................................................................................................724.6.2.AlertType:.................................................................................................74

4.7. Ticker: .........................................................................................................77Chng 5: Giao din ha cp thp........................................................ 78

5.1. Canvas: ........................................................................................................785.1.1.H to:..................................................................................................795.1.2.V trn i tng Canvas:........................................................................795.1.3.Bt s kin trong cc i tng Canvas:..................................................825.1.4.Game action:.............................................................................................855.1.5.S kin con tr:.........................................................................................87

5.2. Graphics: .....................................................................................................895.2.1.Mu sc:....................................................................................................905.2.2.Nt v:.......................................................................................................935.2.3.Font ch:...................................................................................................985.2.4.V cc i tng hnh nh (image): .......................................................1015.2.5.Cc phng thc tnh tin i tng:.....................................................1035.2.6.Vng xn (Clipping regions): .................................................................105

Chng 6: Lu trthng tin vi RMS.................................................... 1066.1. Gii thiu RMS .........................................................................................1066.2. Duyt danh sch Record vi RecordEnumeration ....................................1156.3. Sp xp bng RecordComparator..............................................................117

6.4.

Lc record vi RecordFilter ......................................................................119

6.5. Nhn thng ip khi Record Store thay i..............................................1216.6. X l li khi thao tc vi Record Store.....................................................122

Chng 7: Kt ni mng vi Generic Connection Framework (GCF) 1247.1. Gii thiu GFC..........................................................................................1247.2. Lc lp ...............................................................................................1247.3. Kt ni HTTP:...........................................................................................127

7.3.1.Khi to kt ni: .....................................................................................1277.3.2.Cc c im ca kt ni HTTP bng J2ME: ........................................1307.3.3.Thng s kt ni: ....................................................................................137

7.4. Kt ni socket Datagram (UDP) ...............................................................1387.5. Kt ni TCP socket ...................................................................................1417.6. Gi v nhn SMS ......................................................................................144

Phn 2 : Web Service v ng dng "ng K Hc Phn" .................... 149Chng 8: Gii thiu Web Service...........................................................149

8.1. ng dng phn tn (Distributed Application) ..........................................1498.1.1.Gii thiu................................................................................................1498.1.2.Cc vn ny sinh trong h thng ng dng phn tn.........................1508.1.3.Hn ch ca nhng m hnh ng dng phn tn trc y....................151

8.2. Web Service ..............................................................................................152


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8.2.1.nh ngha ..............................................................................................1528.2.2.Thnh phn cbn ca Web service:.....................................................1528.2.3.Hot ng ca Web service....................................................................1528.2.4.u im ca web service .......................................................................155

8.3. Cc thnh phn chnh ca Web Service ....................................................1578.3.1.SOAP (Simple Object Access Protocol) ................................................1578.3.2.WSDL (Web Service Definition Language) ..........................................162

Chng 9: ng dng ng k hc phn.................................................. 1729.1 c t chng trnh:..................................................................................172

9.1.1Tng quan:..............................................................................................1729.1.2Cc chc nng chnh: .............................................................................172

9.2 Kin trc chng trnh: .............................................................................1749.2.1M hnh kt ni: .....................................................................................1749.2.2M hnh bo mt (m ho password): ....................................................176

9.3 Phn tch - thit k:....................................................................................1779.3.1M hnh use case: ...................................................................................1779.3.2c t mt s use case chnh:.................................................................178

9.4 Thit k m hnh d liu: ..........................................................................1839.4.1M hnh thc th kt hp: ......................................................................1839.4.2Cc bng d liu:....................................................................................1839.4.3Chi tit cc bng d liu:........................................................................1849.4.4Rng buc d liu:..................................................................................1889.4.5M hnh d liu: .....................................................................................1909.4.6Cc chc nng store procedures: ............................................................1909.4.7Thit k lp:............................................................................................191

9.5 Ci t - th nghim:.................................................................................1929.5.1Yu cu phn cng: ................................................................................1929.5.2Yu cu phn mm: ................................................................................1939.5.3Giao din chng trnh:..........................................................................193

Chng 10: Tng kt ............................................................................... 20510.1 Kt lun: ....................................................................................................20510.2 Hng pht trin: ......................................................................................207

Ti liu tham kho ...................................................................................... 210

Ph Lc A:Hng dn sdng cng c Sun Wireless ToolKit 2.3 ...... 211Ph Lc B:Xy dng v Sdng Web Service....................................... 217Ph Lc C:Gii thiu cc thvin JSR ................................................... 222


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Danh Sch Cc Hnh

Hnh 1.1 Cc thit b J2ME h tr..............................................................................6Hnh 1.2 Cc thnh phn ca J2ME............................................................................7Hnh 1.3 Configurations v cc thit b ......................................................................9Hnh 1.4 Cu trc chng trnh J2ME......................................................................11Hnh 1.5 Cu trc chng trnh MIDP .....................................................................11Hnh 2.1 Cu trc thit b MID .................................................................................17Hnh 3.1 Command Exit ...........................................................................................34Hnh 3.2 Command Label .........................................................................................36Hnh 3.3 nh x soft-button......................................................................................36Hnh 4.1 S cc lp giao din ho ..................................................................40

Hnh 4.2 Giao din i tng DateField...................................................................46Hnh 4.3 Giao din i tng Gauge ch tng tc ............................................48Hnh 4.4 Giao din i tng Gauge ch khng tng tc .................................49Hnh 4.5 Giao din i tng StringItem .................................................................52Hnh 4.6 Giao din i tng TextField ...................................................................56Hnh 4.7 Giao din i tng ChoiceGroup ch mt la chn ...........................59Hnh 4.8 Giao din i tng ChoiceGroup ch nhiu la chn.........................60Hnh 4.9 Giao din i tng List dng menu..........................................................67Hnh 4.10 Giao din i tng List cho php chn nhiu la chn .........................68Hnh 4.11 Giao din i tng TextBox...................................................................71

Hnh 4.12 Giao din i tng Alert ........................................................................76Hnh 4.13 Giao din Ticker.......................................................................................77Hnh 5.1 Cc phng thc vng cong ...............................................................94Hnh 5.2 Cc phng thc v hnh ch nht ............................................................95Hnh 5.3 Cc phng thc h trv Text ................................................................97Hnh 5.4 Cc nh dng trong Text Graphic .............................................................97Hnh 5.5 Cc phng thc to font.........................................................................100Hnh 5.6 V bng i tng Immutable Image ......................................................101Hnh 5.7 V bng i tng Mutable Image ..........................................................102Hnh 5.8 Cc nh dng v tr trong Graphics .........................................................103

Hnh 7.1 Lc cc lp trong th vin GCF .......................................................125Hnh 7.2 Kt ni UDP.............................................................................................138Hnh 7.3 Kt Ni TCP.............................................................................................141Hnh 7.4 Lc lp th vin WMA.....................................................................145Hnh 8.1 Hot ng ca Web Service.....................................................................152Hnh 8.2 Mt client truy xut n nhiu web services cng lc.............................154Hnh 8.3 Mt web service c th triu tp n cc web services khc...................155Hnh 8.4 Web Service Endpoint..............................................................................162Hnh 9.1 Kin trc chng trnh ng dng.............................................................174Hnh 9.2 M hnh m ho password .......................................................................176


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Hnh 9.3 Lc use case ......................................................................................177Hnh 9.4 M hnh thc th kt hp ER...................................................................183Hnh 9.5 Rng buc chu trnh .................................................................................189Hnh 9.6 M hnh csd liu ..............................................................................190

Hnh 9.7 M hnh Lp.............................................................................................192Hnh 9.8 S cc mn hnh ..................................................................................194Hnh 9.9 Mn hnh welcome...................................................................................195Hnh 9.10 Mn hnh ng nhp...............................................................................196Hnh 9.11 Confirm ..................................................................................................197Hnh 9.12 Menu chc nng.....................................................................................198Hnh 9.13 Mn hnh ng k hc phn l thuyt....................................................199Hnh 9.14 Mn hnh ng k hc phn thc hnh ..................................................200Hnh 9.15 Mn hnh xem thi kho biu ................................................................201Hnh 9.16 Mn hnh xem kt qu hc tp ...............................................................202Hnh 9.17 Mn hnh xem phiu ng k.................................................................203Hnh 9.18 Mn hnh xem thi kho biu ................................................................204Hnh 10.1 Hng pht trin thc t ........................................................................207Hnh A.1 Cng c Sun WirelessToolkit 2.3 ...........................................................211Hnh A.2 Mn hnh chnh ca cng c ...................................................................212Hnh A.3 To project mi .......................................................................................212Hnh A.4 Cc options cho project ...........................................................................213Hnh A.5 Chnh sa ni dung file Jad v Jar ..........................................................214Hnh A.6 Bin dich project .....................................................................................215Hnh A.7 ng gi ng dng..................................................................................216Hnh B.1 To project Web Service .........................................................................217Hnh B.2 Khai bo lp v hm................................................................................218Hnh B.3 Export nhiu hm cng lc......................................................................219Hnh B.4 Mn hnh thc thi Web Service ca IE ...................................................219Hnh B.5 File WSDL...............................................................................................220Hnh B.6 Cng c Stub Generator ..........................................................................221Hnh B.7 Cc options ca cng c Stub Generator.................................................221


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Danh Sch Cc Bng

Bng 2.1 Cu trc file manifest.................................................................................19Bng 2.2 Cu trc file JAD.......................................................................................20

Bng 3.1 Lp MIDlet ................................................................................................27Bng 3.2 Lp Display ...............................................................................................29Bng 3.3 Lp Displayable.........................................................................................32Bng 3.4 Cc Command Type ..................................................................................37Bng 3.5 Command v CommandListener ...............................................................38Bng 3.6 Item v ItemStateListener..........................................................................39Bng 4.1 Lp Screen.................................................................................................42Bng 4.2 Lp Form ...................................................................................................44Bng 4.3 Lp Item ....................................................................................................45Bng 4.4 Lp DateField ............................................................................................46

Bng 4.5 Lp Gauge .................................................................................................49Bng 4.6 Lp StringItem...........................................................................................51Bng 4.7 Cc Rng Buc ca TextField ...................................................................53Bng 4.8 Lp TextField ............................................................................................55Bng 4.9 Lp ChoiceGroup ......................................................................................58Bng 4.10 Lp Image................................................................................................62Bng 4.11 nh dng ImageItem ..............................................................................62Bng 4.12 Lp ImageItem ........................................................................................63Bng 4.13 So snh List v ChoiceGroup ..................................................................65Bng 4.14 Lp List....................................................................................................66

Bng 4.15 So snh TextField v TextBox ................................................................69Bng 4.16 Lp TextBox............................................................................................70Bng 4.17 Lp Alert..................................................................................................73Bng 4.18 AlertType.................................................................................................75Bng 4.19 Lp Ticker ...............................................................................................77Bng 5.1 Truy vn kch thc Canvas......................................................................79Bng 5.2 Lp Canvas ................................................................................................81Bng 5.3 Giao tip vi Application Manager ...........................................................81Bng 5.4 M Phm.....................................................................................................83Bng 5.5 S kin keyPressed ....................................................................................84Bng 5.6 S kin Game Action.................................................................................85Bng 5.7 Bt s kin trong Game Action .................................................................86Bng 5.8 S kin con tr...........................................................................................87Bng 5.9 Lp Graphics .............................................................................................90Bng 5.10 Cc phng thc v .................................................................................93Bng 5.11 X l Text................................................................................................96Bng 5.12 Gi tr Anchor ..........................................................................................96Bng 5.13 X l Font ch .........................................................................................98Bng 5.14 Cc gi tr Font ........................................................................................99Bng 5.15 V hnh nh............................................................................................101


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Bng 5.16 Gi tr Image Anchor .............................................................................103Bng 5.17 Cc phng thc tnh tin .....................................................................103Bng 5.18 Vng xn................................................................................................105Bng 6.1 M hnh Record Store..............................................................................107

Bng 6.2 Lp RecordStore......................................................................................109Bng 6.3 Lp RecordEnumeration .........................................................................117Bng 6.4 Cc gi tr hng sp xp record...........................................................118Bng 6.5 Lp RecordListener .................................................................................121Bng 7.1 Lp Connector .........................................................................................128Bng 7.2 Mode Kt Ni ..........................................................................................128Bng 7.3 Cc Request Method chnh......................................................................130Bng 7.4 Cc phng thc set/get Request Method ...............................................131Bng 7.5 Cc phng thc truy vn HTTP Header................................................134Bng 7.6 Ly thng s kt ni ................................................................................137Bng 7.7 Lp DatagramConnection .......................................................................139Bng 7.8 Lp Datagram..........................................................................................140Bng 7.9 Thuc tnh ca SocketConnection...........................................................142Bng 7.10 Lp SocketConnection ..........................................................................143Bng 7.11 Cc interfaces chnh ca WMA.............................................................144Bng 9.1 Danh sch cc Use Case ..........................................................................178Bng 9.2 Table ChuyenNganh ................................................................................184Bng 9.3 Table SV ..................................................................................................184Bng 9.4 Table MonHoc .........................................................................................185Bng 9.5 Table GV .................................................................................................185Bng 9.6 Table Lop.................................................................................................185Bng 9.7 Table Lop_MonLT ..................................................................................186Bng 9.8 Table Lop_MonTH..................................................................................187Bng 9.9 Table PhanCongTH .................................................................................187Bng 9.10 Table DangKyLT...................................................................................187Bng 9.11 Table DangKyTH ..................................................................................187Bng 9.12 Table ThongBao ....................................................................................188


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Cc chvit tt, thut ngc sdng

API Application Program InterfaceCDC Connected Device Configuration

CLDC Connected Limited Device Configuration

Configurationc t qui nh cc th vin gc J2ME phi h trcho mt dng

phn cng.

DES Thut ton m ha kha b mt 64 bits

GCF General Connection Framework

IIS Internet Information Services-Web server chun trn Windows

J2EE Java 2 Enterpise Edition, phin bn Java cho nhng d n ln.

J2ME Java 2 Micro Edition, phin bn Java cho nhng thit b nh.

J2SEJava 2 Standard Edition, phin bn Java ra i u tin, dnh cho

PC thng thng.

JCP T chc Java Community Process

JDK Java Development Kits

JSRJava Specification Requests, nhng yu cu cn b sung cho cc

phin bn Java.

JSR-172 Th vin truy xut web service cho ngn ng J2ME.

JSR-177 Th vin m ha v bo mt cho ngn ng J2ME.

KVM My o Java cho mi trng CLDC.

MIDlet Tn gi chung cho cc ng dng J2ME.

MIDP Mobile Information Device Profile.

MMSMultimedia Message Service, tin nhn hnh nh, m thanh, video

cho di ng.

PDA Personal Digital Assistant.

Profile Cc tp th vin cp cao nh ngha trn nn Configuration.

RMS RecordStore Management System, cch lu tr ca J2ME.


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SMSShort Message Service, tin nhn thng thng cho in thoi di

ng.

SOAPSimple Object Access Protocol, nh dng thng ip ca Web

Service.

Symbian Hiu hnh cho in thoi di ng ca hng Symbian.

UDDI Universal Description, Discovery, and Integration

Web Service Giao thc gi hm t xa da trn XML v HTTP.

WMA Wireless Message API

WSDL Web Service Definition Language

XML Extensible Markup Language


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Java Mobile

Li Ni u

Mng in thoi di ng xut hin ti Vit Nam tu nhng nm 1990 v

theo thi gian, s lng cc thu bao cng nh cc nh cung cp dch v di ng ti

Vit Nam ngy cng tng. Cng vi s pht trin ca s lng thu bao di ng l

sa dng ho cc dch v hng n thit b di ng. Ngy nay in thoi di ng

khng ch cn mang chc nng gi in hay nhn tin thng thng m cn l mt

thit b gii tr, tra cu thng tin rt tin li. Do , xy dng cc ng dng cho in

thoi di ng ang l mt yu cu tt yu trong xu th hin nay. Ngnh cng nghipphn mm cho cc thit b di ng c xem nh mt mnh t mu mv ha hn

em li nhiu t la doanh thu.

Hai hng pht trin ng dng trn in thoi di ng ph bin hin nay l

s dng ngn ng C++ trn nn hiu hnh Symbian v J2ME. Cc ng dng vit

trn nn Symbian c cc u th truy cp trc tip cc ti nguyn ca in thoi cng

nh h trh thng tp tin, th mc nh my tnh c nhn v c h tr trc

tip bi hiu hnh. Tuy nhin hiu hnh Symbian li c kch thc kh ln

nn ch c cc th hin thoi tng i cao cp, v xy dng ng dng dng

Symbian API cng phc tp hn.

i trng vi Symbian API l cng ngh J2ME vi kch thc nh gn,

tin dng, c h trbi hu ht cc th hin thoi mi ra i, k c cc in

thoi c hiu hnh Symbian. J2ME khng nhng l mt ngn ng hng n cc

thit b di ng m cn l ngn ng chnh lp trnh trn cc thit b gia dng, th

tn dng in t v cc thit b thng minh khc. Chng ta c th ni i tng ca

ngn ng J2ME l rng hn rt nhiu so vi C++ trn nn Symbian. Ti thi im

hin ti, ngn ng J2ME khng h trc nhiu tnh nng nh C++ trn Symbian

nhng li c nhng u im tri hn.

J2ME l mt ngn ng nh, gn nhng rt cht ch v d nm bt, vi

nhng lp trnh vin c kinh nghim vi Java vic lp trnh vi J2ME trnn rt

1


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d dng. J2ME cn l mt ngn ngc cc t chc m ngun mng h mnh

m v pht trin rt nhanh chng, JCP (Java Community Process-

http://www.jcp.org) l mt chng trnh do Sun thnh lp lun tip thu cc kin

v a ra cc c t mi dnh cho Java ni chung v J2ME ni ring. Cc c t

ny thng c tip u ng JSR v l cc tnh nng b sung mi cho J2ME.

Nhng JSR quan trng c thc nhc n nh JSR-82 (Bluetooth), JSR

205 (Gi tin nhn SMS, MMS), JSR-172 (Web service), JSR-177 (Security and

Trust Services), JSR 184 (3D Game) Cc c t ny ngy cng phong ph v

phn no pht trin nhanh hn c s pht trin ca phn cng.

Tht kh so snh gia cc dng ngn ng lp trnh vi nhau v mi loi uc u v khuyt im ring. Trong lun vn ca mnh, chng ti chn nghin cu

v J2ME v nhng u im kh r rng nu trn, mt khc chng ti cng mun

th sc mt lnh vc kh mi m l tip cn vi phn mm m ngun m.

V chng trnh ng dng, tnh kh thi v thc t ngy cng c cao.

Chng ti nhn thy xu hng m rng cc ng dng trn web sang in thoi di

ng ang c ch trng. Thng mi in t (e-commerce) ang tin dn sang

thng mi di ng (m-commerce). Vi thc trng Vit Nam hin nay, s ngi s

hu my vi tnh c nhn, c bit l my tnh xch tay cha nhiu nhng t l s

ngi c in thoi di ng li kh cao. Vic chuyn cc ng dng thng mi t

mi trng web sang mi trng di ng s khin s tin dng tng cao, s ngi

s dng dch v trc tuyn chc chn s tng nhanh v i vi nhiu ngi chic

in thoi di ng d s dng hn rt nhiu so vi chic my tnh "phc tp v kh

hiu".

ng dng chng ti chn thc hin bc chn vo lnh vc kh mi m

ny l ng dng "ng K Hc Phn" qua mng di ng. i vi sinh vin khoa

cng ngh thng tin, h thng ng k hc phn SMS qua mi trng web l mt

ng dng rt quen thuc. Chng ti mun pht trin ng dng ca mnh nh mt

mrng ca h thng ng k hc phn ny trn in thoi di ng nhm h trcc

bn sinh vin c th s dng cc tin ch ca h thng m khng cn phi c my

2
http://www.jcp.org/http://www.jcp.org/


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tnh kt ni mng. Vi ng dng ny, tnh tin dng ca h thng ng k hc phn

SMS c mrng. Ch cn c mt in thoi di ng h trGPRS cc bn sinh

vin c thng k hc phn ngay c khi ang v qu n tt nhng vng internet

cha ph bin nhng ph sng di ng hay khi ang di chuyn trn tu xe V

mt s iu kin c bit ca in thoi, hin nay ng dng ny ch chy trn

chng trnh gi lp. Tuy nhin, chng ti hi vng trong mt tng lai rt gn, khi

cc th hin thoi mi c gi thnh va phi ra i v h trmt s cng ngh

nh WebService, m ho m chng ti ang s dng xy dng phn mm th

ng dng ny c thc p dng rng ri trong thc t cho sinh vin ca khoa.

Cn phi ni thm, ng dng hin ti hon ton c th s dng c trong thc tVit Nam nhng c mt si hi v thit b kh t tin (xin xem thm Chng

10, phn Kt Lun), ch khng ch mi l l thuyt trn giy t.

Vi vic xy dng thnh cng h thng ng k hc phn qua mng in

thoi di ng, chng ti rt t tin v vic xy dng cc h thng thng mi di ng

ln hn. Trong tng lai gn, khch hng c th ngi trn taxi mua v my bay, t

ch khch sn, xem li ti khon ngn hng vi chic in thoi di ng nh b.

Chic in thoi di ng s tr thnh mt cng c giao dch khng th thiu trong

thi i mi, thi i ca thng mi in t ton cu.

Lun vn c trnh by thnh hai phn lp:

Phn 1: Gii thiu v l thuyt nn tng ca J2ME, cc th vin, cc k thut lp

trnh, ng gi ng dng di ng.

Chng 1. Tng quan v J2ME : Gii thiu tng quan v J2ME, cc c im v

cc thnh phn con.

Chng 2. Gii thiu CLDC v MIDP: Trnh by chi tit v hai thnh phn quan

trng ca J2ME dnh cho in thoi di ng, mi trng pht trin ng dng J2ME.

Chng 3. Cc vn cbn ca chng trnh MIDlet: Chng ny s trnh by

nhng c im quan trng nht ca mt ng dng J2ME, cc bc cbn xy

dng ng dng ny.

3


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Chng 4. Giao din ha cp cao: Trnh by v th vin ha cp cao nh

Form, List, TextBox trong J2ME.

Chng 5. Giao din ha cp thp: Trnh by v lp trnh ha cp thp, cc

phng thc v, x l font, game action trong J2ME.

Chng 6. Lu tr thng tin vi RMS: Trnh by v Record Management System,

mt cch lu tr ring ca J2ME.

Chng 7. Lp trnh mng vi GCF: Trnh by v kh nng lp trnh mng trong

J2ME.

Phn 2: Gii thiu v Web Service, mt cng ngh rt mi xy dng cc ng

dng thng mi in t phn tn v gii thiu chi tit vng dng cng nhngnh gi, tng kt.

Chng 8. Gii thiu vng dng phn tn v web service

Chng 9. Trnh by chi tit vng dng "ng K Hc Phn"

Chng 10. nh gi, tng kt cc kt qut c v hng pht trin trong

tng lai.

Tuy u t kh nhiu th giv cng sc vo lun vn ny nhng chc

chn chng ti cng khng trnh khi nhng sai st. Rt mong nhn c kin

ng gp v s thng cm ca qu thy c v cc bn! Xin chn thnh cm n!

Kim Anh Anh Tun

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Phn 1: Kin thc nn tng J2ME

Chng 1: Tng quan v J2ME

1.1 Gii thiu J2ME (Java 2 Micro Edition)

J2ME l mt nhnh ca ngn ng lp trnh JAVA c pht trin nhm hng

ti vic lp trnh cho cc thit b nh (micro) c b nh, kh nng hin th v x

l hn ch.

Ban u Java c xy dng ch gm mt phin bn duy nht, ngy nay c

bit n vi tn J2SE (Java 2 Standard Edition), vi phng chm l vit mt ln,

chy trn mi mi trng (Write once, run anywhere). Java c hnh thnh trn

tng xy dng mt ngn ng m lp trnh vin ch cn vit mt ln duy nht

nhng ng dng c th chy trn bt c mi trng no c h trmy o Java (Java

Virtual Machine). lm c vic ny, Java s dng mt phng thc bin dch

m ngun tng i khc so vi cc ngn ng lp trnh truyn thng. B bin dch

Java khng bin dch m ngun trc tip sang m my m bin dch sang mt dngm trung gian m my o Java hiu c (m bytecode). Khi c nhu cu s dng

ng dng, my o Java sc m trung gian ny v dch ra m my v thc thi; nh

vo qu trnh trung gian mt ng dng Java c th chy trn bt k mi trng

no c ci t my o Java tng thch.

c gii thiu ln u vo nm 1995, ngy nay mc tiu Java nhm n cng

thay i kh nhiu. Java hin nay khng ch nhm n h my tnh bn n

thun; hai nm sau ngy u c ra mt, mt phin bn Java mi l J2EE (Java 2

Enterprise Edition) c gii thiu nhm ti vic pht trin cc ng dng c qui

m ln hn.

Phin bn mi nht c thm vo dng ngn ng Java l J2ME (Java 2 Micro

Edition). J2ME nhm n vic pht trin ng dng cho cc ng dng c nng lc

hn ch nhu gii m k thut s TV set-top boxes, in thoi di ng

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1.2 L do chng ta cn J2ME

Ngy nay ngnh cng nghip sn xut thit b di ng trn th gii ang pht

trin nhanh chng. Cc thit b di ng ngy cng hin i hn, thng minh hnv ngy cng c nhiu tnh nng ni bt. n c nh chic in thoi di ng, ngy

nay chng khng chn thun m nhn chc nng hi thoi m cn c thm

nhiu chc nng nh chp nh, nghe nhc, xem phim nh mt trung tm gii

tr. Cc thit b gia dng khc nh l vi ba, TV cng ngy cng c trang b

nhng tnh nng hin i hn. Nhu cu pht trin phn mm cho cc thit b di

ng, gia dng ngy cng tng cao v c nh gi l mt ngnh cng ngh c th

em li nhiu t la doanh thu. Mt thc tt ra cho cc nh pht trin phn

mm trn cc thit b ny l hin nay khng c mt chun ha no dnh cho cc nh

sn xut phn cng. Cc thit b trn th trng hin nay rt a dng v mang nhiu

c im cng nh cu hnh khc nhau. Trc thc t, vic c th chy trn

nhiu mi trng l mt li th rt ln ca ngn ng Java. Cc nh pht trin Java

cho ra i ngn ng J2ME hng n vic pht trin phn mm cho cc thit b

di ng. Ngn ng J2ME thc s l mt ngn ng nh gn, d nm bt, cht ch v

thch hp cho cc thit b c kh nng hn ch. Cc thit b di ng trn th trng

hin nay, c bit l in thoi di ng hu ht u h trrt tt ngn ng J2ME v

J2ME thc s trthnh mt trong nhng ngn ng ph bin nht trong lnh vc

lp trnh di ng.

Hnh 1.1 Cc thit b J2ME h tr

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1.3 Cc thnh phn ca J2ME:

Hnh 1.2 Cc thnh phn ca J2ME

Khi nim thit b di ng l tng i rng ln. Chng bao hm nhng thit b

c kch thc vt l khc nhau nhiu ln v cho d cng kch thc nhng thit b

ny vn c kh nng x l cng nh hin th khc nhau ( nhng chic in thoi

hin th 12,000 pixels cho n nhng chic PDA 20,000 pixels). p ng c

nhu cu khc nhau ca nhng thit b ny, bn thn ngn ng J2ME cng c chia

thnh nhng thnh phn nh hn.

Chng ta s tm hiu hai khi nim mi l Configurations v Profiles.

1.3.1 Configuration:

p ng nhu cu cho nhiu chng loi thit b khc nhau, Sun a ra khi

nim Configuration. Khi nim Configuration c mi lin h cht ch vi my o

Java. Ni chnh xc hn, mt Configuration qui nh nhng thnh phn v nhng

th vin gc ca ngn ng Java m my o phi h trcho configuration .

Vic phn chia thnh nhng Configurations khc nhau ch yu da vo kh

nng b nh, nng lc hin th, nng lc x l v kh nng kt ni mng ca cc

thit b. Nh chng ta bit, cc thit b di ng rt khc nhau v ngun ti

nguyn, v kh nng phn cng. Vi nhng thit b c nng lc hn ch, nu ta a

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qu nhiu th vin h trvo my o trn thit b s gy chm h thng v d

tha khng cn thit. Vi nhng thit b c kh nng cao hn, chng ta sa thm

nhiu th vin h trvo my o gip ch cho cng vic lp trnh ca cc nh pht

trin. Do , nhu cu phn chia thnh nhiu Configurations l vic cn thit.

Hin nay Sun a ra hai loi Configurations khc nhau:

CDC (Connected Device Configuration):

512 kb (minimum) b nh chy Java

256 kb (minimum) b nhcp pht ng.

Kt ni mng lin tc, bng thng rng.

CLDC(Connected Limited Device Configuration): 128 kb (minimum) b nh chy Java

32 kb (minimum) b nhcp pht ng.

Giao din ngi dng hn ch

Nng lng tiu tn t (ch yu dng pin)

Kt ni mng Wireless, chm.

Vic phn chia ny thc cht cng ch mang tnh tng i. Cng ngh hin nay

ang pht trin kh nhanh, v vic pht trin ny cng lm cho ranh gii gia cc

loi Configuration ny trnn khng r rng.

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Hnh 1.3 Configurations v cc thit b

1.3.2 Profile:

Configuration thc ra ch cung cp mt s rt t cc lp v ngi pht trin ng

dng hu nh khng th ch lm vic n thun vi cc configuration ny. Ta c th

thy iu ny qua mt v d: cc configuration khng h trcc cng c v giao

din (GUI), do nu ch dng configuration th lp trnh vin phi xy dng tt c

cc chc nng giao din tu. V l do ny Sun linh hot v a thm mt khi

nim mi nm tng trn ca configuration, l Profiles.

Ta c th xem Profile l mt mrng ca khi nim Configuration. Profile nh

ngha cc th vin gip lp trnh vin pht trin pht trin ng dng cho mt dng

thit b no . V d Mobile Information Device Profile (MIDP) nh ngha cc

hm API cho cc thnh phn giao din, nhp liu v x l s kin, lu tr, kt ni

mng v x l thi gian, ph hp vi mn hnh hin th v kh nng x l ca cc

thit b di ng. Profile MIDP c nh ngha trn nn tng ca CLDC. Ngoi ra

chng ta cn mt s Profile tiu biu khc nh

PDA Profile: tng t MIDP, nhng vi th trng l cc my PDA vi mn

hnh v b nhln hn

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Hnh 1.4 Cu trc chng trnh J2ME

Nu chng trnh c bin dch vi CDC, chng trnh s chy trn cc my

o truyn thng v mang cc c tnh nh chng trnh J2SE.

Nu chng trnh c bin dch vi CLDC, chng trnh s chy vi my o

chuyn bit KVM v nhng c tnh ring do CLDC i hi.

Vi chng trnh xy dng bi MIDP, chng ta c cu trc chuyn bit sau:

Hnh 1.5 Cu trc chng trnh MIDP

Tng di cng l h iu hnh c h tr my o Java (KVM), bn trn l

CLDC v trn cng l MID Profile. Lc ny khi nim Vit mt ln, chy bt c

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mi trng no ca Sun khng cn ng hon ton v xut hin my o chuyn

bit KVM. Mt s chng trnh vit bng MIDP s khng chy trn mi trng

J2SE v ngc li. Tuy nhin chng ta phi cm kch cc n lc ca Sun gip

cho Java trthnh mt trong nhng ngn ng c kh nng c lp vi mi trng

bn di nht hin nay, iu ny ng vi c mi trng thit b di ng.

nhng phn tip theo chng ta s tm hiu k hn v hai thnh phn cbn

ca J2ME l Configuration v Profile.

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Chng 2: Gii thiu CLDC v MIDP

2.1. CLDC

2.1.1. Yu cu phn cng:

Khi ra yu cu v phn cng vic xem xt cc chi tit nh b x l, b nh

v cc phn mm hin c trn cc thit b di ng l vic v cng quan trng. Nhm

mc ch phc v ti a cc thit b hin c trn th trng, CLDC ch ra cc yu

cu v b nhv khng ra yu cu no cho cc thnh phn khc. Yu cu ti

thiu c th s dng CLDC nh sau: 128 kilobytes chy JVM v cc th vin ca CLDC. Khng phn bit loi

b nhs dng (Rom, Flash,), b nhca thit b phi bo lu c ni

dung lu di, ngay c khi ngt in. B nh ny thng c gi l

nonvolatile memory.

32 kilobytes b nh trng cp pht cc i tng (objects). B nh ny

thng c gi l volatile memory (hay l heap).

2.1.2. Yu cu phn mm:

CLDC c yu cu ti thiu v mt phn mm. Hiu hnh phi tng thch vi

JVM v c chc nng qun l cc ng dng Java, bao gm:

Cho php chn v kch hot ng dng

Cho php gbng dng khi thit b

2.1.3. My o Java:

Do cc thit b di ng dng CLDC thng c ti nguyn hn ch nn Sun

ra my o Java KVM phc v ring cho cc thit b ny. My o KVM thc cht l

mt b phn con ca cc my o trn mi trng J2SE v J2EE nn cng c nhiu

hn ch v khc bit so vi hai phin bn trn.

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Mt s hn ch:

Khng h tr kiu d liu float: Vic s l s float i hi nhiu ti

nguyn x l, ngoi ra cc thit b di ng khng c nhng cu hnh phn

cng dnh ring cho vic x l s float nn trong J2ME chng ta khng

th khai bo cc bin, mng float, cc hm cng khng nhn tham s v

tr v cc s float.

Phng thc finalize: Trong J2SE, chng ta c th khai bo phng thc

finalize (tng t nh phng thc destructor). Garbage Collector s gi

phng thc ny trc khi hy b mt i tng, phng thc ny

thng c dng thu hi cc ti nguyn h thng nh sockets, filehandles trc khi i tng b ph hy. Tuy nhin trong J2ME chng

ta khng c phng thc finalize.

Error Handling: Trong J2ME chng ta vn c h trcc cng c v by

li (ch yu thng qua try v catch). Tuy nhin kh nng v x l li ca

J2ME cng hn ch hn vi hai phin bn cn li.

Khng h trvic s dng code ca cc ngn ng lp trnh khc

Khng h trReflection: Trong J2SE v J2EE, chng ta c th dng cc

lp Reflection tm hiu thng s mi trng my o Java ang thc thi.

Khng h trThreadGroup: mi thread c qun l ring bit, khng

cn lp ThreadGroup. Nu mun iu khin mt lc nhiu threads chng

ta c th dng mng hoc Vector.

J2ME cng cn mt sim khc bit so vi J2SE v J2EE, mt trong nhngkhc bit chnh l qu trnh Class Verify (tm dch l kim tra lp). Cc lp trc

khi c load s thng qua mt qu trnh kim tra v s hp l v tnh nguyn

vn. y l mt c ch quan trng bo m an ton (security) ca Java. Qu

trnh ny trong J2SE v J2EE c th chim n 50 kbytes b nh, trong J2ME

chng c chia thnh 2 giai on:

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Tin kim tra (Pre-verification): Trc khi mt lp c np vo thit b,

mt phn mm sc s dng thm vo mt s thng s b sung vo

file class. Qu trnh ny gim thi gian v b nhcn thit my o thc

hin giai on 2 trong qu trnh kim tra. File class sau khi c tin

kim tra s tng dung lng khong 5%

Kim tra ni thit b (In-device verification): Khi thit b np cc file class

c tin kim tra, cng c kim tra trong thit b s thc hin mt vi

kim tra xc nhn tnh hp l ca on code. Nu pht hin mt li no

b kim tra s pht sinh bo co v t chi np lp i tng vo b

nh. Qu trnh ny i hi t b nhv ti nguyn hn nhiu ln so vitrong J2SE v J2EE.

CLDC khng h trtt c cc lp v th vin c h trtrong ngn ng Java

truyn thng m ch h trnhng th vin tht s cn thit i vi thit b di ng.

Ngoi ra trong CLDC chng ta cng c h trvic truy vn mt s thuc tnh

ca h thng:

Ly thng tin v platform ca thit b:

System.getProperty("microedition.platform")

Ly thng tin v bng m mc nh:

System.getProperty("microedition.encoding")

Ly trng tin v version v tn ca configuration:

System.getProperty("microedition.configuration")

Ly thng tin v Profile:

System.getProperty("microedition.profiles")Ngoi ra chng ta c th truy cp lp Runtime ly cc thng s v thit b nh:

Runtime rtime= Runtime.getRuntime();

System.out.println("Total memory: " + rtime.totalMemory());

//thng tin v tng b nh

System.out.println("Free memory: " + rtime.freeMemory());

//thng tin v b nhtrng

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2.2. MIDP:

2.2.1. Yu cu phn cng:

Mn hnh t nht phi c 96 x 54 pixels

C t nht mt thit b nhp liu: bn phm hoc mn hnh cm ng.

C t nht 128 kilobytes b nhnon-volatile chy cc thnh phn ca MID

C t nht 8 kilobytes b nhnon-volatile lu cc cu hnh chng trnh v d

liu

C t nht 32 kilobytes chy Java

C kt ni khng dy (wireless network)

2.2.2. Yu cu phn mm:

Mc d hiu hnh ca tng thit b c th khc nhau nhng phi p ng

c cc yu cu ti thiu sau:

Hiu hnh phi h trvic x l ngt, x l exception v h trx l

ha bitmap xut d liu ra mn hnh Hiu hnh phi nhn c tn hiu nhp liu (input) v chuyn d liu

cho my o Java

Hiu hnh phi h trvic c/ghi vo b nhnon-volatile. Khng i hi

hiu hnh phi nh ngha file system nhng phi cho php ghi d liu dng

persistent (khng b mt i khi tt my, ngt in).

Phi h tr truy xut mng, c bit phi c tnh nng c/ghi d liu thng

qua mng khng dy (wireless network).

2.2.3. Cu trc MID Profile:

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Hnh 2.1 Cu trc thit b MID

Tng di cng l phn cng ca thit b di ng. Bn trn phn cng ta c h

iu hnh iu khin cc hot ng.

Bn trn hiu hnh ta c th chia thnh 2 phn ring bit. Chng ta s thy

phn bn phi l cc chng trnh native application (tm dch l chng trnh

nguyn gc). Trc khi J2ME ra i, thng thng y l loi chng trnh duy

nht c trn cc thit b. y l loi chng trnh c nh sn xut a sn vo

my di ng lc sn xut nh chng trnh chn ting chung, chnh thng sin

thoi, chnh gi Chnh nhJ2ME ra i chng ta mi c chc nng ci t thm

cc chng trnh c vit thm vo in thoi.

CLDC l nn tng c bn cho MID Profile, cc chng trnh MIDP (MIDP

Applications) c th s dng cc lp c cung cp bi c CLDC v MIDP. Ngoira chng ta cn c cc lp OEM (original equipment manufacturer) l cc lp do

cc nh sn xut cung cp thm cho in thoi (cc hng nh Nokia, Samsung,

Motorola thng c thm nhiu lp cp cao h trcho lp trnh vin) v bn trn

l cc ng dng c xy dng t cc lp ny, cc ng dng ny thng ch chy

trn cc in thoi ca hng cung cp th vin lp OEM.

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2.2.4. MIDlet Suite:

Chng ta gi chng trnh Java chy trn thit b di ng l mt MIDlet. MIDlet

s s dng cc lp cung cp bi CLDC v MIDP. Mt MIDlet Suite (mt b

MIDlet) cha mt hay nhiu ng dng MIDlet c nn chung trong mt file JAR

(Java Archive).

Cu trc file Jar:

Ngoi cc file lp v resource, trong file Jar cn c mt tp tin c gi l

manifest. y l tp tin m t ni dung ca ton file Jar. Tp tin ny c tn

manifest.mf v bn thn n cng c nn trong file Jar. Trong file manifest chng

ta c thnh ngha cc thuc tnh ca file jar nhng quan trng nht l 6 thuc tnhsau:

- MIDlet-Name

- MIDlet-Version

- MIDlet-Vendor

- MIDlet- (mi mt MIDlet cn mt mu thng tin ny)

- MicroEdition-Profile

- MicroEdition-Configuration

Nu 1 trong 6 thng tin ny thiu th thit b s t chi chy cc ng dng trong file

Jar ny.

Bng sau m t cc thuc tnh c thnh ngha trong file manifest:

Thuc tnh Mc ch Bt buc

MIDlet-Name Tn ca b MIDlet C

MIDlet-Version S phin bn CMIDlet-Vendor Cho bit ngi to MIDlet Suite C

MIDlet- Tham chiu n tng MIDlet trong b

MIDlet (trong file Jar), mi mt MIDlet cn

mt mu tin ny, mu tin ny gm 3 mu tin

con:

Tn MIDlet

C

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File Icon MIDlet (c th khng cn)

Tn lp s c np khi thc thi MIDlet

ny

MicroEdition-

Profile

Tn profile cn thit chy MIDlet ny,

thng l MIDP1.0 hoc MIDP2.0

C

MicroEdition

Configuration

Configuration cn chy MIDlet (thng

l CLDC 1.0)

C

MIDlet-Icon File icon (.pgn) ca b MIDlet Khng

MIDlet-Description M t (text) ca b MIDlet Khng

MIDlet-Info-URL a ch trang web nh pht trin MIDlet KhngBng 2.1 Cu trc file manifest

y l mt v dn gin ca file manifest:

MIDlet-Name: Todo List

MIDlet-Version: 1.0

MIDlet-Vendor: Core J2ME

MIDlet-1: TodoList, /images/Todo.png, Todo.TodoMIDlet

MicroEdition-Profile: MIDP-1.0

MicroEdition-Configuration: CLDC-1.0

File JAD (Java Application Descriptor File):

Bn cnh file Jar, mt bng dng MIDlet cn c thm file JAD (.jad) cung

cp thng tin v cc MIDlet trong file JAR. Vic t ra file JAD c mt s mc ch

sau: Cung cp thng tin v ni dung file Jar. T thng tin ny, b qun l ng dng

trn thit b mi quyt nh ng dng ny c thch hp chy trn thit b hay

khng.

Cung cp cc tham s dng cho MIDlet trnh thay i file JAR. File JAR

cha m ng dng nn cn trnh b thay i.

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Danh sch cc thuc tnh trong file Jad:

Thuc tnh Mc ch Bt buc

MIDlet-Name Tn ca b MIDlet C

MIDlet-Version S phin bn C

MIDlet-Vendor Cho bit ngi to MIDlet Suite C

MIDlet- Tham chiu n tng MIDlet trong b

MIDlet (trong file Jar), mi mt MIDlet cn

mt mu tin ny, mu tin ny gm 3 mu tin

con:

Tn MIDletFile Icon MIDlet (c th khng cn)

Tn lp s c np khi thc thi MIDlet

ny

C

MIDlet-Jar-URL a ch URL ca file Jar C

MIDlet-Jar-Size Kch thc file Jar tnh bng byte C

MIDlet-Data-Size Kch thc ti thiu tnh bng byte ghi

cc d liu ca chng trnh (persistent

data)

Khng

MIDlet-Description M t MIDlet (dng text) Khng

MIDlet-Delete-

Confirm

Thng bo nhc nhkhi xa MIDlet Khng

MIDlet-Install-

Notify

URL nhn thng bo v qu trnh ci t Khng

Bng 2.2 Cu trc file JAD

Ta cng c thnh ngha thm cc thuc tnh ring, bt u bng MIDlet- ty

theo mc ch ca lp trnh vin. Nhng thuc tnh sau phi ging nhau file Jad

v file manifest (nm trong file Jar):

- MIDlet-Name

- MIDlet-Version

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- MIDlet-Vendor

- MIDlet- for each MIDlet

- MIDlet-Jar-URL

Nu cc thuc tnh ny khng ging nhau, ng dng s b thit b t chi. Vi

cc thuc tnh cn li, nu file Jad v file manifest khc nhau th thuc tnh trong

file Jad sc u tin hn.

Sau y l mt v dn gin v file Jad:

MIDlet-Name: Todo List

MIDlet-Version: 1.0MIDlet-Vendor: Core J2ME

MIDlet-Jar-URL: http://www.corej2me.com/TodoMIDlet.jar

MIDlet-Jar-Size: 17043

MIDlet-1: TodoList, /images/Todo.png, Todo.TodoMIDlet

y c mt cu hi c t ra: Ti sao phi ghp nhiu ng dng MIDlet

thnh mt file nn dng JAR. Mc ch ca vic kt hp ny gip cho cc ng dng

MIDlet c nn chung ny c th chia x chung cc ti nguyn vi nhau. Mt v

d c th cp n l vic chia s chung cc Record Store: trong mi trng

J2ME chng ta khng c khi nim file system; mi nhu cu lu tr d liu c

thng qua cc Record. Trong mt b MIDlet Suite th tn cc Record phi phn bit

v cc ng dng MIDlet cng chung trong mt b s c th chia s cc Record ny

vi nhau. iu ny kh thun li, n c th gip chng ta vit cc games cng chia

s danh sch ngi chi, danh sch cc ngi chi c im cao nht

Khi np ng dng vo thit b ta cng lc np hai file .Jar v .Jad; file .Jad s l

file thc thi v file .Jar cha m thc thi ca chng trnh

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2.2.5. Mi trng pht trin ng dng J2ME

Phn ny chng ta s tm hiu v cc phn mm cn thit dng pht trin mt

ng dng J2ME, cch ci t v cu hnh cc phn mm ny. Ngoi ra chng ta s

nghin cu v cc tools pht trin c h trthm.

vit mt ng dng J2ME chng ta cn t nht 3 chng trnh sau:

Java Development Kit (JDK) , version 1.3 hoc cao hn (phin bn mi nht tnh

n lc lun vn c thc hin l phin bn 1.42)

http://java.sun.com/products/jdk/

Connected, Limited Device Configuration (CLDC):

http://java.sun.com/products/cldcMobile Information Device Profile(MIDP):

http://java.sun.com/products/midp/

Ghi ch: y xem Microsoft Windows nh hiu hnh mc nh c s dng,

nu ngi dng s dng hiu hnh khc th phi c mt siu chnh ph hp

vi hiu hnh .

Ci t cc phn mm:

Ci t JDK:

File ci t JDK c dng file thc thi (.exe), chng ta ch cn chy v lm theo

cc hng dn s ci t thnh cng b JDK (gi s th mc ci t l C:\jdk1.3.1)

Set bin mi trng (Environment Variable):

Vic set bin mi trng gip chng ta chy trnh bin dch t bt c v tr no,

khng cn phi g tn v ng dn y ca trnh bin dch.

Vo Control Panel, Chn System. Chn Environment (hoc Advanced/Environment)

Tm mc PATH, thm th mc \bin ca th mc JDK (v d C:\JDK\bin)

vo bin mi trng PATH (PATH=..;c:\jdk\bin;)

Ci t CLDC v MIDP:

File CLDC v MIDP c dng zip, ta gii nn vo chung mt th mc (v d

C:\J2ME).

22
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Th mc J2ME c dng:

C:\J2ME

j2me_cldc (th mc cha CLDC)

midp1.0.1.fcs (th mc cha MIDP)

Sau cng ta set hai bin mi trng PATH v CLASSPATH nh sau:

PATH=C:\jdk1.3.1\bin;C:\j2me\j2me_cldc\bin;C:\j2me\midp1.0.3fcs\bin;

CLASSPATH=C:\j2me\midp1.0.3fcs\classes;. (du "." ch th mc hin hnh)

Lc ny ta cng c xy dng ng dng J2ME. Chng ta c nhiu cng c

h trcho qu trnh bin dch v thc thi MIDlet nhng ban u chng ta s tm

hiu cch s dng nhng cng c cbn nht v l cng c chun ca J2ME.Qu trnh bin dch v thc thi ng dng J2ME phi qua mt s thao tc bng dng

lnh (command lines), chng ta gi s th mc cha m ngun l th mc

C:\Midlets.

Ta s xy dng mt ng dng J2ME n gin m phng qu trnh bin dch v

thc thi, ng dng c tn Welcome v file source code c tn Welcome.java

C:\Midlets\Welcome\Welcome.java

Qu trnh bin dch v Pre-verify:

bin dch ta chuyn n th mc cha ng dng (C:\Midlets\Welcome\) v

gi lnh:

javac -bootclasspath c:\j2me\midp1.0.3fcs\classes Welcome.java

hoc

javac bootclasspath %CLASSPATH% Welcome.java

(CLASSPATH l bin mi trng c nh ngha trc thay cho

c:\j2me\midp1.0.3.fcs\classes;.)

Javac l chng trnh bin dch ca b JDK, thng s -bootclasspath ra lnh cho

chng trnh dich ly cc file lp c s ti th mc c:\j2me\midp1.0.3fcs\classes

(y l file lp c sca MIDP). Nu khng c thng s ny, file lp c sca

JDK sc s dng, file lp csny khc vi file ca MIDP nn J2ME c th

khng s dng c.

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Sau qu trnh ny file Welcome.class sc to ra v mc ch chung th mc

vi file m ngun.

Sau khi c file class ta cn thc hin vic pre-verify ( c cp phn trc

ca lun vn).

Ta thc thi dng lnh:

preverify -classpath c:\j2me\midp1.0.3fcs\classes;. -d . Welcome

hoc

preverify classpath %CLASSPATH% d . Welcome

Tng t, thng s classpath ch ra v ch cc file class ti th mc

c:\j2me\midp1.0.3fcs\classes v th mc hin hnh (du .). Thng s -d ch ra thmc output kt qu l th mc hin hnh.

Qu trnh Pre-verify ny l bt buc, nu khng thc hin cng on ny thit

b di ng s tchi thc thi ng dng

Thc thi ng dng MIDlet:

Ta thc thi cu lnh:

midp -classpath . Welcome

Thng s class path ch ra th mc cha file cn thc thi, y l th mc hin

hnh, tn ng dng l Welcome (file Welcome.class c pre verify).

Trn y l qu trnh cbn nht bin dch v thc thi mt ng dng J2ME,

s dng nhng tnh nng cao hn (to MIDlet Suite cha nhiu MIDlet, to file

Jad, file Jar) xin vui lng xem file hng dn trong a CD nh km hoc xem ti

liu ca cc b bin dch. tit kim thi gian, chng ta thng dng cc cng c

tin ch nh Sun Wireless Toolkit, xin xem phn ph lc bit cch s dng.

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Chng 3: Cc vn c bn ca chng

trnh MIDlet

3.1. Cu trc cbn:

Chng ta gi chung cc chng trnh J2ME l MIDlet. Cc chng trnh MIDlet

ny u c k tha t lp MIDlet. Khng ging nh chng trnh trn my PC,

cc chng trnh MIDlet khng cn hm main() thc thi. Trc ht chng ta s

xem xt v vng i (lifecycle) ca cc ng dng MIDlet.

Mt chng trnh MIDlet khi c np vo thit b c nhng trng thi sau: Paused: Mt chng trnh MIDlet sc a vo trng thi paused sau khi

thc hin phng thc khi to (constructor) v trc khi c chng trnh

qun l ng dng (application manager) trn thit b gi thc thi. Trong qu

trnh hot ng, chng trnh MIDlet cng c th ba tr li trng thi

paused bi thit b (khi cn tr li cuc gi n ) hoc bi chnh chng

trnh MIDlet.

Active: Chng trnh MIDlet ang thc thi.

Destroyed: Chng trnh MIDlet gii phng tt c ti nguyn v c

tt bi trnh qun l ng dng trn thit b.

3.2. Xy dng mtng dng MIDlet:

Chng ta xy dng mt ng dng MIDlet bng cch k tha (extends) lpMIDlet. Lp ny thc cht l mt interface v chng ta phi khai bo ba hm sau

y: startApp(), pauseApp() v destroyApp(). y l mt v d v mt chng trnh

MIDlet n gin:

public class Shell extends MIDlet

{

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// phng thc khi to (constructor) khng bt buc phi c

public Shell(){ }

// c application manager gi trc khi thc thi MIDlet

public void startApp(){}

// c gi trc khi tm dng MIDlet

public void pauseApp(){ }

// c gi trc khi kt thc chng trnh

public void destroyApp(boolean unconditional){ }

}

3.3. Lp MIDlet:Nh cp, mi ng dng ca ta u k tha t lp MIDlet. Lp ny c

khai bo nh sau:

public abstract class MIDlet {

protected abstract void startApp()

throws MIDletStateChangeException;

protected abstract void pauseApp();

protected abstract void destroyApp(boolean

unconditional) throws

MIDletStateChangeException;

}

Ba hm c nu trn l ba hm bt buc chng ta phi xy dng khi to ngdng MIDlet. Lp MIDlet c cha trong package javax.microedition.midlet

Sau y l danh sch cc hm thng dng trong lp MIDlet:

Phng thc: M t:

abstract void destroyApp

(boolean unconditional)

Hm ny c gi khi c nhu cu tt MIDlet. y

l ni gii phng cc ti nguyn dng.

abstract void pauseApp() Hm ny c gi gii phng cc ti nguyn

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trc khi tm dng chng trnh.

abstract void startApp() c gi khi MIDlet sp c a vo trng thi

thc thi (active state).

final void notifyDestroyed() Bo cho application manager bit chng trnh

MIDlet gii phng ti nguyn v cn c tt.

(sau khi gi destroyApp)

final void notifyPause() Bo cho application manager bit chng trnh

MIDlet gii phng ti nguyn v mun vo trng

thi tm dng (sau khi gi pauseApp)

final void resumeRequest() Bo cho application manager ta cn a MIDletvo trng thi hot ng trli. (Sau application

manager s gi startApp).

final String getAppProperty

(String key)

Ly cc thng s ca chng trnh (t file jad v

file manifest).

Bng 3.1 Lp MIDlet

y chng ti xin m t hai qu trnh quan trng nht ca mt ng dng MIDlet

l qu trnh khi np v qu trnh thot ng dng:

Qu trnh np:

User chn kch hot ng dng MIDlet

Application manager khi to cc bin, gi phng thc khi to

(constructor).

ng dng MIDlet sau khi c np vo b nhsc a vo trng thi

paused (nhng hm pauseApp() s khng c gi). Application manager gi hm startApp(). Thc cht hm startApp() s

c gi mi khi ng dng c a vo trng thi thc thi (active); khi ta

tm ngng ng dng v c nhu cu kch hot tr li hm ny cng c

gi.

Qu trnh thot:

User chn thot chng trnh

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Hm destroyApp() c gi, hm ny phi bo m vic gii phng ti

nguyn.

Hm notifyDestroyed() c gi bo cho application managerng dng

gii phng ht ti nguyn v sn sng b tt.

3.4. Lp MIDletStateChangeException:

Khi tm hiu v package javax.microedition.midlet, cn mt lp quan trng

chng ta phi ch n l lp MIDletStateChangeException. ng dng MIDlet c

hai hm c kh nng to ra (throw) Exception ny l hm destroyApp() v hm

startApp().Nh chng ta bit, trc khi ng dng c a vo trng thi active th hm

startApp() sc gi. Nu trong qu trnh gi hm ny dn n pht sinh li (thit

b ht ti nguyn, ti nguyn cn dng ang b ng dng khc chim) th

MIDletStateChangeException s c to ra. Trong qu trnh thot, hm

destroyApp() cng c th pht sinh exception ny, v d nh khi chng ta thot m

chng trnh ang nhn d liu ht sc quan trng t network ta c th pht sinh

exception dng vic thot.

Ta xem xt hm destroyApp(boolean condition):

Tham s condition y c mt ngha kh th v, nu tham s ny l true d

chng ta c pht sinh exception MIDletStateChangeException th ng dng vn

thot; ch khi no tham s ny l false th exception MIDletStateChangeException

mi c kh nng hy vic thot chng trnh.

3.5. Display

ng dng ca chng ta chc chn c nhu cu xut d liu ra mn hnh. Vic

ny trong mt ng dng MIDlet do mt i tng thuc lp display m nhim.

Lp ny nm trong package javax.microedition.lcdui,package ny cha hu nh tt

c cc lp phc v cho vic pht trin giao din ca ng dng.

Chng ta s xem xt mt s hm quan trng nht ca lp Display:

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Phng thc: M t:

static Display getDisplay(MIDlet m) Ly i tng Display ca MIDlet

Displayable getCurrent() Ly i tng Displayable hin thi (s

cp sau)

void setCurrent (Alert alert,

Displayable nextDisplayable)

void setCurrent (Displayable

nextDisplayable)

To i tng alert (s cp sau)

boolean isColor() Cho bit thit b c h trmu hay khng?

int numColors() C bao nhiu mu c h tr?Bng 3.2 Lp Display

Mt MIDlet s c mt v ch mt i tng Display iu khin vic th hin d

liu. i tng Display khng c phng thc khi to m c khi to trc tip

t phng thc static ca lp.

V d:

Display display=Display.getDisplay(this);

Tham s u vo l mt MIDlet, y chng ta gi hm t lp k tha t

MIDlet nn c th truyn vo con tr this. Thc ra cng dng chnh ca Display l

cho php hin thi tng no ln mn hnh hin thi. Cc i tng c th hin

th ln mn hnh l cc i tng thuc lp Displayable (sc gii thiu sau), v

d nh form, TextBox, Canvas,Screen

Ta xt v d sau:

public class Vidu extends MIDlet{

Form mainForm;

Vidu{

mainForm=new Form(.);

}

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public void startApp()

{

Display display=Display.getDisplay(this);

Display.setCurrent(mainFrom);

.

}

.

}

Ban u ta khi to mt form th hin ln mn hnh, sau khi ng dng

MIDlet c np vo b nh constructorc gi to form. Sau , phng

thc startApp() c gi, trong phng thc ny ta chn Form mainForm th

hin ln mn hnh bng lnh setCurrent. Khi ng dng b tm ngng (paused) v

phc hi tr li (resume) th hm startApp() cng c gi v form li c th

hin trn mn hnh. n y chng ta c th hnh dung c phn no tc dng ca

i tng Display.

3.6. Lp Displayable:

Nh cp, mt ng dng MIDlet ch c mt i tng Display duy nht v

i tng Display ny dng th hin cc i tng Displayable ln mn hnh.

Nh tn ca lp Displayable cho chng ta thy, y l cc i tng c kh nng

hin th thng tin ln mn hnh thit b. Lp Displayable bao gm 2 lp con l lp

Screen v lp Canvas. C th chng c nh ngha nh sau:

abstract public class Displayable;

public abstract class Canvas extends Displayable;

public abstract class Screen extends Displayable;

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Lp Screen cn c chia thnh nhng lp con nh hn nh: TextBox, List,

Form v Alert. y l nhng lp giao din cp cao (v phn ln cc cng vic th

hin ca cc lp ny c ci t sn). Cc i tng ca lp Canvas c gi l

nhng i tng ha cp thp, cc lp ny cho php chng ta x l cc giao tc

ha tng di, x l mu sc v ch yu dng trong qu trnh vit games.

nhng phn sau chng ta s tm hiu k hn v cc lp giao din cp thp ln cp

cao.

* To mt i tng Displayable:

Thng thng chng ta khng to trc tip mt i tng thuc lp Displayablem s dng cc lp con ca n. vit cc ng dng ha ta thng k tha t

lp Canvas:

public class GameScreen extends Canvas

{

draw images, shapes, text

}

Khi xy dng cc ng dng tin ch (t dng n cc chc nng ha) ta s dng

cc lp ha cp cao nh Form, TextBox hoc k tha t cc lp ny.

Cc hm chnh ca lp Displayable:

Phng thc: M t:

void addCommand(Command cmd) Thm mt i tng Command vo i

tng Displayable

void removeCommand (Command

cmd)

Xa b mt i tng Command ti

tng Displayable

void setCommandListener

(CommandListener l)

Thm CommandListener vo i tng

Displayble

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boolean isShown() Kim tra i tng Displayable c c

th hin trn thit b hay khng?

Bng 3.3 Lp Displayable

*Ghi ch: Cc i tng Command v CommandListener sc cp chi tit

phn sau.

Ti thi im ny chng ta c th hnh dung mt Command nh mt nt n iu

khin trong ng dng ca chng ta, CommandListener c tc dng chuyn cc s

kin khi ngi dng kch hot mt Command n lp x l ca ng dng. bt

c cc s kin c chuyn ti khi ngi dng kch hot mt Command, ngdng ca chng ta phi ci t hm commandAction. V d nh sau:

public void commandAction(Command c, Displayable s)

{

if (c == cmExit)

{

destroyApp(true);

notifyDestroyed();

}

}

3.7. Qun l cc skin (event)

Ngy nay, vic x l s kin l mt trong nhng vn cbn nht ca mt

chng trnh. C th ni, trong th gii phn mm ngy nay khng mt chng

trnh no li khng c kh nng tng tc vi ngi dng, do vic qun l cc s

kin pht sinh l mt vn m bt c phn mm no cng phi thc hin. Qu

trnh x l cc s kin pht sinh bao gm 3 qu trnh cbn:

Phn cng (thit b di ng) phi cm nhn c khi c mt s kin pht

sinh: ngi dng n mt phm, mt cable c cm vo hay rt ra.

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Phn mm trn thit b (hiu hnh) phi nhn bit c c s kin pht

sinh

Hiu hnh chuyn thng tin v s kin cho ng dng, bt u ty l

cng vic ca nhng lp trnh vin J2ME. Ty theo cc thng tin v s

kin m chng ta phi a ra cc gii php thch hp

Trong phn ny chng ta s ch nghin cu v cc s kin c pht sinh

nhng ng dng s dng cc chc nng ha mc cao (Form, TextBox), cn

cc s kin pht sinh nhng ng dng s dng cc th vin ha mc thp

nh cc games sc cp sau.Thc cht nhn c thng bo t hiu hnh v cc s kin pht sinh lp

ng dng chnh ca chng ta phi ci t (implement) cc listener. Trong J2ME

h tr sn cho chng ta 2 listener l CommandListener v ItemStateListener. Lp

CommandListener c hm commandListener() v tng ng lp ItemStateListener

c hm itemStateChange(), y l 2 hm chng ta cn ci t nhn bit cc s

kin xy ra. Trc khi i su vo x l cc s kin chng ta s tm hiu 2 tc nhn

chnh pht sinh mt s kin l Command v Item.

3.7.1. Command & CommandListener

Ta nh ngha Command l mt i tng gi thng tin v mt s kin (Event).

Ni mt cch n gin nht th command nh mt nt n (button) trn ng dng di

ng, khi ta chn nt ny th s pht sinh mt s kin tng ng.

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Hnh 3.1 Command Exit

Trong v d trn ta thy Command Exit tng ng vi mt nt n trn in

thoi. Vic xem mt Command tng ng vi mt nt n trn thit b l mt quan

nim nhm n gin ha vn nhng khng hon ton chnh xc. Nu chng ta

xem xt cc hn ch v kch thc v mn hnh v s lng nt n c trn thit b

th vn s trnn phc tp hn, c nhng form s lng command c th nhiu

hn s nt n chc nng trn thit b, lc ny cc command c t chc theo dngmenu. Trc tin, ta s tm hiu cc cng vic phi lm thm mt command vo

ng dng:

To mt command lu gi thng tin v event

Thm command ny vo Form, TextBox hay Alert (cc i tng

displayable)

Thm mt listener vo cc Form hay TextBox trn.

Khi pht hin mt event c kch hot, b listener s gi hm commandListener()

v truyn cc thng tin v event lm thng s cho hm. Sau y l mt on code v

d:

public class TestCommand extends MIDlet implements CommandListener

{

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private Form fmMain; // To mt form

private Command cmExit; // To mt command thot khi ng dng

...

fmMain = new Form("Core J2ME"); // Khi to form

cmExit = new Command("Exit", Command.EXIT, 1); // Khi to command

...

fmMain.addCommand(cmExit); // Thm command vo form

fmMain.setCommandListener(this); // Thm b listener cho form

...

//hm dng bt cc s kinpublic void commandAction(Command c, Displayable s)

{

if (c == cmExit)//nu l command exit, thot chng trnh

{

destroyApp(true);

notifyDestroyed();

}

}

}

Qua v d trn ta thy vic to mt command v x l n tng i n gin.

im quan trng cn ch l lp ng dng ca ta phi ci t mt b listener

(trong v d trn ta implements CommandListener) v phi cung cp hm

commandListener x l cc events.

Khi chng ta to mt Command c ba thng s cn cung cp:

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Label: on vn bn c xem nh nhn ca command. Nh trong hnh 3.1, Exit

l nhn ca command. Nh trong hnh 3.2, ta thy y cng l label ca command

nhng c th hin dng khc: dng menu.

Hnh 3.2 Command Label

Type: Tht thun tin nu ta c th nh x mt command vi mt nt trn thit b

(ta gi l soft-button). Gi s ta c mt command tn help v nh xc vi

HELP Button trn thit b th tht trc quan v d dng cho ngi dng.

Thng s Type gip chng ta lm chuyn ny: Ta chn Command.HELP. Nu thit

b khng c nt help, thng s ny khng c ngha v command c i x nh

cc command thng thng. Tuy nhin, ta cn lu khi ta tt type l

Command.HELP th khng c ngha khi ta chn command ny cc hng dn s

c pht sinh m ta cn phi lm vic ny trong hm commandAction(). Thng s

type ch gip vic nh x cc nt soft-button c d dng.

Hnh 3.3 nh x soft-button

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Cc type c h tr:

Gi tr M t

BACK Dng i ngc li mn hnh trc .

CANCEL Dng hy cng vic ang thc hin

EXIT Dng thot chng trnh

HELP Cung cp thng tin trgip

ITEM Dng nh x mt Command vi mt item trn mn hnh. Gi

s khi ta dng giao din List, khi chn mt item ta c th gn item

ny vi mt command pht sinh mt s kin no .

OK Xc nhn mt yu cu no hoc thot khi mn hnh thngbo.

SCREEN Thng thng thit b khng c cc soft button tng ng vi cc

command dng ny. Vic th hin cc command s ty vo tng

thit b (s c cc v d)

STOP Dng mt cng vic ang thc hin.

Bng 3.4 Cc Command Type

Nh cp, cc type ch c ngha khi thit b c mt nt tng ng dnh

ring cho type ny (nh nt help ca thit b hnh 3.3).

Priority: u tin, dng sp xp cc command t trn xung di hay tri sang

phi khi c th hin chung dng menu. Hnh 3.2 th hin command Upload c

u tin cao hn command Download. Gi tr ny cng cao th u tin cng thp.

Sau y l cc hm chnh ca lp Command v CommandListener (hai lp ny nm

trong package javax.microedition.lcdui).Lp javax.microedition.lcdui.Command

C php ngha

Command (String label, int

cmdType, int priority)

Hm khi to, cc thng s c trnh by

bn trn

int getCommandType() Cho bit Type ca Command

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int getLabel() Cho bit Label ca Command

int getPriority() Cho bit u tin

Lp javax.microedition.lcdui.CommandListener

void commandAction(Command

c, Displayable d)

c gi khi command c nm trn i tng

Displayable d pht sinh mt s kin

Bng 3.5 Command v CommandListener

3.7.2. Item v ItemStateListener

S kin (event) khng chc pht sinh thng qua kch hot commands m

cn c thc pht sinh thng qua cc items. Mt item l mt b phn c th gn

km ln trn cc form. ChoiceGroup, DateField, Gauge v TextField l cc dng

khc nhau ca Item v mi dng u c th pht sinh cc s kin (chng ta s tm

hiu v cc items ny trong phn Ha Cp Cao). Items ch c thc s dng

nh mt thnh phn ca form, khc vi Commands c th c s dng trong

Form, TextBox, List v Canvas.

Khi chng ta thm mt Item vo Form, x l c cc s kin pht sinh ta

phi ci t mt Listener (y l ItemStateListener). Khi c mt thay i trn Item(v d nh ta chn mt mc trong ChoiceGroup hay thay i d liu ca mt

DateField) th i tng listener sc thng bo c mt s kin pht sinh cng

cc thng tin v s kin ny. S kin ny s kch hot hm itemStateChanged()

c chng ta ci t.

Hin ti MIDP h tr cc loi Items sau: ChoiceGroup, DateField, Gauge,

ImageItem, StringItem v TextField. y c mt ngoi l l hai loi StringItem v

ImageItem khng h trpht sinh s kin mc d chng l lp con ca lp Item.

Chng ta ci t mt listener trong lp Form, khi mt Item pht sinh s kch hot

hm itemStateChanged(), tuy nhin khng phi khi chng ta thay i gi tr nhiu

items cng lc th itemStateChanged() sc gi by nhiu ln. y c mt

lut c ra:

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Nu mt Item b thay i, hm itemStateChanged() phi c gi i vi

Item ny trc khi nhng thay i trn nhng Item sau c nhn

bit.

Nu chnh bn thn MIDlet thay i gi tr mt Item (gi s chng ta dng

m lnh thay i ch khng phi do ngi dng), hm

itemStateChanged() khng c gi.

Nu thit b nhn bit c ngi dng chuyn t Item ny sang Item

khc (chuyn focus) th hm itemStateChanged() phi c gi trc khi

chuyn sang Item k tip.

Sau y l cc hm quan trng khi s dng Item:

Lp javax.microedition.lcdui.Item

C php ngha

String getLabel() Ly nhn ca Item

void setLabel(String label) t nhn cho label

Lp javax.microedition.lcdui.ItemStateListener

void itemStateChanged(Item item) c gi khi gi tr item thay i

Bng 3.6 Item v ItemStateListener

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public class Display

public abstract class Displayable

public abstract class Screen extends Displayable

public abstract class TextBox extends Screen

public abstract class List extends Screen

public abstract class Item

public class ChoiceGroup extends Item implements Choice

public class DateField extends Item

public class TextField extends Itempublic class Gauge extends Item

public class ImageItem extends Item

public class StringItem extends Item

pubilc abstract class Canvas extends Displayable

public class Command

public class Ticker

public class Graphics

public interface Choice

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4.2. Form:

Form l lp thng dng nht trong cc i tng Displayable. Nu khi s dng

Texbox, List, Alert, ta ch c th hin th mt i tng duy nht ti mt thi im

th khi s dng Form, chng ta c th hin th nhiu i tng c chc nng tng

t ti cng mt thi im. lm c iu ny, ta ch cn to mt i tng thuc

lp Form v gn vo i tng ny mt hay nhiu i tng thuc lp con ca lp

Item (TextField, DateField, ChoiceGroup, Gauge, ImageItem, StringItem). Lp

Form cng h trsn chc nng cun mn hnh nu thit b khng hin th ht tt c

cc Item trong mt mn hnh.

Lp Form h trsn cc phng thc thm, xo, sa cc thnh phn trong Form

mt cch d dng. Khi gn mt i tng thnh phn - mt i tng thuc lp con

ca Item - vo Form, ta s nhn c mt gi tr tr v tng ng vi ch mc ca

thnh phn trong Form. Vi ch mc ny, ta c th tham chiu n thnh phn

ny khi cn tra cu hay thay i thng tin i tng.

Cc phng thc v chc nng tng ng ca lp Form:

Lp Form: javax.microedition.lcdui.FormPhng thc Chc nng

Form (String title) Khi to mt Form

Form (String title, Item[] items) Khi to mt Form v thm cc Item vo

Form

int append (Image image) Thm mt bin Image vo Form

int append (Item item) Thm mt bin Item vo Form

int append (String string) Thm mt bin String vo Form

void delete (int itemNum) Xo mt Item khi bit ch mc ca n

void insert (int itemNum, Item item) Chn mt Item vo v tr ch mc cho trc

Item getItem (int ItemNum) Ly mt bin Item khi bit ch mc ca n

void set (int itemNum, Item item) Thay bin Item ch mc cho trc bng

bin Item mi

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void setItemStateListener(

ItemStateListener iListener)

Thm bin Listener vo Form

int size () Ly s Item trong Form

Bng 4.2 Lp Form

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4.3. Item:

Mt Item l mt thnh phn c th thm vo Form. Cc lp con ca Item gm:

ChoiceGroup, DateField, TextField, Gauge, ImageItem v StringItem.

Item thng c dng chung vi lp ItemStateListener. Khi mun bt s kin

ca 1 Item, ta ch cn kt buc Item vi 1 bin listener thuc lp

ItemStateListener. Bin listener ny s lng nghe cc s kin v t gi phng thc

itemStateChanged() khi Item kt buc vi n c s thay i. Trong phng thc

ny, ta c th vit x l cho cc s kin cn bt ca Item.

Vd: to 1 DateField cho Form v gn bin listener bt s kin:

private Form fmMain;

private DateField fdToday;

...

fmMain = new Form (Core J2ME);

dfToday = new DateField (Today: , DateField.DATE);

...public void itemStateChanged(Item item) {

if (item == dfToday)

//x l

}

Cc phng thc v chc nng tng ng ca lp Item:

Lp Item: javax.microedition.lcdui.Item

Phng thc Chc nng

String getLabel () Ly nhn ca Item

void setLabel (String label) Gn nhn cho Item

Bng 4.3 Lp Item

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4.3.1. DateField:

Dng hin th mt i tng ngy gi (java.util.Date) v cho php ngi

dng thay i gi tr ngy giny bng cc phm bm ca thit b di ng. Giao

din DateField d dng, khi to mi mt i tng DateField, ta c th la chn

cho php ngi dng ch thay i gi tr ngy thng, gipht hay c hai :

Hnh 4.2 Giao din i tng DateField

Cc phng thc v chc nng tng ng ca lp DateField:

Lp DateField: javax.microedition.lcdui.Date

Phng thc Chc nng

DateField (String label, int mode) Khi to mt i tng DateField

DateField (String label, int mode,

TimeZone timeZone)

Khi to mt i tng DateField vi

mi gicho trc

Date getDate () Ly gi tr ngy thng ca i tng

void setDate (Date date) Gn gi tr ngy thng ca i tngint getInputMode () Ly thng tin kiu nhp liu

void setInputMode () Gn kiu nhp liu

Bng 4.4 Lp DateField

C th chn 1 trong 3 kiu nhp liu cho i tng DateField:

DATE: ch cho php ngi dng thay i gi tr ngy thng

TIME: ch cho php ngi dng thay i gi tr gipht

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DATE_TIME: cho php ngi dng thay i gi tr c ngy thng ln

gipht

VD:

//to 1 bin DateField cho php ngi dng nhp ngy thng

DateField dfDate = new DateField(Ngay thang,DateField.DATE);

//gn ngy thng hin thi cho bin dfDate

dfDate.setDate(new Date());

//cho php ngi dng thay i thng tin ngy thng v gipht

dfDate.setInputMode(DateField.DATE_TIME);

....

//ly thng tin ngy thng ca bin dfDate (thng ly gi tr mi m ngi dng va nhp )

Date dNewDate=new Date;

dNewDate=dfDate.getDate();

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4.3.2. Gauge:

Gauge dng biu din tin hon thnh mt vic no (download, upload...)

hoc cp t thp n cao (ca m lng, kh...). Gauge c trng bi hai gi

tr: gi tr hin hnh v gi tr cc i cho php. Gi tr hin hnh ny lun c duy

tr gia 0 v gi tr cc i. Gauge gm hai dng:

Ch tng tc (Interactive mode): Trong ch ny, i tng

Gauge sc v dng cc thanh song song c chiu cao tng dn

biu th cc cp t thp n cao. Ngi s dng c thiu chnh

gi tr hin thi ca Gauge bng cc phm bm. VD: iu chnh m

lng cao thp.

Hnh 4.3 Giao din i tng Gauge ch tng tc

Ch khng tng tc (Non-interactive mode): i tng c biu

din dng cc thanh song song c chiu cao bng nhau, ngi dng

khng c php thay i gi tr ca n. Ngi lp trnh s lp trnh

cho i tng ny tng cp nht gi tr theo thi gian.

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Hnh 4.4 Giao din i tng Gauge ch khng tng tc

Cc phng thc v chc nng tng ng ca lp Gauge:

Lp Gauge: javax.microedition.lcdui.Gauge

Phng thc Chc nng

Gauge (String label, boolean interactive,

int maxValue, int initValue)

Khi to mt i tng Gauge

int getValue () Ly gi tr hin thi ca Gauge

void setValue (int value) Gn gi tr cho i tng Gauge

int getMaxValue () Ly gi tr cc i cho php ca Gauge

void setMaxValue (int maxValue) Gn gi tr cc i cho php cho

Gauge

boolean isInteractive () Kim tra Gauge c thuc ch tng

tc khng

Bng 4.5 Lp GaugeVD:

//to 1 bin Gauge cho php ngi dng iu chnh m thanh (ch tng tc)

Gauge gVolume= new Gauge (Volume, true, 6, 2);

//gn Gauge vo Form

fmMain.append(gVolume);

fmMain.setCommandListener(this);

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//to 1 bin Gauge biu din tin trnh Download (ch khng tng tc):

Gauge gDownload = new Gauge(Download Progress, false, 20,1);

//gn Gauge vo Form

fmMain.append(gDownload);

fmMain.setCommandListener(this);

//cp nht gi tr lin tc cho Gauge bng cch s dng 1 bin timer

//khong cch mi ln cp nht l 1000 mili giy

Timer tTimer = new Timer();

DTTask ttTimerTask = new DTTask(); //class DTTask extends TimerTask

tTimer.scheduleAtFixedRate (ttTimerTask, 0, 1000);

//lp DDTaskc vit bn trong MIDlet

private class DTTask extends TimerTask{

public final void run () {

//nu gi tr hin ti ca gDownload < gi tr cc i th tip tc tng, khng th

dng li

if (gDownload.getValue() < gDownload.getMaxValue())

gDownload.setValue(gDownload.getValue()+1);

else

cancel(); //xo bnh thi

}

}

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4.3.3. String Item:

i tng StringItem dng hin th 1 on vn bn ln mn hnh. Ngi dng

chc php xem m khng c thay i ni dung on vn bn ny.

Cc phng thc v chc nng tng ng ca lp StringItem:

Lp StringItem: javax.microedition.lcdui.StringItem

Phng thc Chc nng

StringItem (String label, String text) Khi to mt i tng StringItem

String getText () Ly ni dung on vn bn

void setText (String text) Gn ni dung on vn bn cn hin th

Bng 4.6 Lp StringItem

ly gi tr nhn (label) hay thay i ni dung nhn c th dng cc phng thc

getLabel(), setLabel(String label) ca lp Item.

VD:

//to mt i tng Str

Ng Hien Cu u Java Mobile

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