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韵坪叶
7 years ago
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1 高级用户界面与多线程

2 LCDUI 高级 LCDUI

3 LCDUI 与多线程多线程在手机编程中尤为重要手机游戏开发中, 通常由游戏主线程负责游戏的基本控制, 除此之外还会由一个或者多个线程用于播放背景音乐或声效网络接受数据时, 传输速度通常都比较慢, 因此可以使用一个独立的线程负责接收数据, 另外一个线程负责 UI 界面和与用户的交互

4 LCDUI 与多线程 J2ME 是通过线程体来实现多线程的线程体就是用于实现线程活动的主体, 由 run() 方法来实现实现线程体的方法主要有 : (1) 通过继承 Thread 类构造线程体 (2) 通过实现 Runnable 接口构造线程体

5 LCDUI 与多线程 Thread 类除了实现 Runnable 接口外,CLDC 包中还提供了通过继承 Thread 类来实现线程的方法, Thread 类直接继承了 Object 类, 可以用来实现一个具体的线程构造方法 Thread(); Thread(String name); Thread(Runnable target); Thread(Runnable target, String name);

6 LCDUI 与多线程 Thread 类主要方法 start(), 启动线程并转入就绪状态 run() 定义线程被调度之后所执行的动作, 系统自动调用, 用户不得引用, 由于 Thread 类的 run() 方法没有具体的内容, 所以用户需要创建 Thread 类的子类, 并定义新的 run() 方法 sleep(): 通常在 run() 方法中调用 sleep() 方法使自己放弃 CPU 资源要停止线程往往通过标识符实现

7 LCDUI 与多线程 Thread 类 import javax.microedition.midlet.*; import javax.microedition.lcdui.*; public class mymidlet extends MIDlet{. public void startapp(){. ThreadDemo th = new ThreadDemo(); th.start();. // 添加类中类 public class ThreadDemo extends Thread{ public void run() {

8 LCDUI 与多线程 Runnable 接口创建一个线程时必须实现 Runnable 接口, Runnable 接口为实现多线程提供了通用的协议, 使得对象被激活时可自动执行特定代码实现 Runnable 接口必须实现其中的 run() 方法,run() 方法是线程的主体,Run() 方法中通常使用 sleep() 方法使线程适当休息, 为其它线程让出 CPU 资源

9 LCDUI 与多线程 Runnable 接口 import javax.microedition.midlet.*; import javax.microedition.lcdui.*; public class mymidlet extends MIDlet{. public void startapp(){. Thread th = new Thread(new RunnableDemo()); th.start();. // 添加类中类 public class RunnableDemo implements Runnable{ public void run() {

10 LCDUI 与多线程 Runnable 接口 import javax.microedition.midlet.*; import javax.microedition.lcdui.*; public class mymidlet extends MIDlet implements Runnable{. public void startapp(){. Thread th = new Thread(this); th.start();. // 重写 run() public void run() {

11 实例 1 在控制台循环打印字符串 hello 和 others

12 实例 1 public class mymidlet extends MIDlet { private Display dis; private Form fm = new Form("test"); public void startapp() { dis = Display.getDisplay(this); dis.setcurrent(fm); mythread mt1 = new mythread(); Thread mt2 = new Thread(new myrunable()); mt1.start(); mt2.start();

13 实例 1 public class mythread extends Thread { public void run(){ while(true){ System.out.println("hello"); Thread.sleep(1000); public class myrunnable implements Runnable { public void run(){ while(true){ System.out.println( others"); Thread.sleep(1000);

14 实例 2 实例 2: 界面上有 1 个 StringItem, 要求它上面的数字每隔 1 秒钟变化

15 public class MidletString extends MIDlet { private Display dis; private Form fm = new Form("String test"); private StringItem si = new StringItem("String1",""); int i=0; public void startapp() { dis = Display.getDisplay(this); dis.setcurrent(fm); fm.append(si); mythread th = new mythread(); th.start(); class mythread extends Thread{ public void run(){ while(true){ si.settext(integer.tostring(i)); i++; try{ Thread.sleep(1000); catch(exception ex){

16 实例 3 实例 3: 界面上有 2 个 StringItem, 要求第一个上面的数字每隔 1 秒钟变化, 第二个上面的数字每隔 2 秒钟变化

17 public class MidletString extends MIDlet { private Display dis; private Form fm = new Form("String test"); private StringItem si1 = new StringItem("String1",""); private StringItem si2 = new StringItem("String2",""); public void startapp() { dis = Display.getDisplay(this); dis.setcurrent(fm); fm.append(si1); fm.append(si2); mythread1 th1 = new mythread1(); th1.start(); Thread th2 = new Thread(new mythread2()); th2.start(); System.out.println("other things");

18 class mythread1 extends Thread{ private int i=0; public void run(){ while(true){ si1.settext(integer.tostring(i)); i++; try{ Thread.sleep(1000); catch(exception ex){ class mythread2 implements Runnable{ private int i=0; public void run(){ while(true){ si2.settext(integer.tostring(i)); i++; try{ Thread.sleep(2000); catch(exception ex){

19 实例 4 秒表

20 public class midlet2 extends MIDlet implements CommandListener { private Display dis; private Form frm; private Command exit,ok,exitwatch,start,stop; private Watch watch; public midlet2() { frm=new Form(" 秒表 "); exit=new Command("exit",Command.EXIT,1); ok=new Command("ok",Command.OK,1); exitwatch=new Command("exitwatch",Command.CANCEL,1); start=new Command("start",Command.OK,1); stop=new Command("stop",Command.STOP,1); protected void startapp(){ dis=display.getdisplay(this); dis.setcurrent(frm); frm.addcommand(exit); frm.addcommand(ok); frm.setcommandlistener(this); frm.append(" 争分夺秒 ");

21 public void commandaction(command c, Displayable d){ String str=c.getlabel(); if(str.equals("ok")){ watch=new Watch(); watch.addcommand(exitwatch); watch.addcommand(start); watch.setcommandlistener(this); dis.setcurrent(watch); else if(str.equals("start")){ watch.removecommand(start); watch.addcommand(stop); watch.startwatch(); else if(str.equals("stop")){ watch.removecommand(stop); watch.addcommand(start); watch.stop(); else if(str.equals("exitwatch")){ dis.setcurrent(frm); else if(str.equals("exit")){ this.notifydestroyed();

22 public class Watch extends Form implements Runnable { private TextField text; private boolean flag; private int count=-1; public Watch() { super(""); flag=true; text=new TextField("","",50,TextField.UNEDITABLE); this.append(text); public void startwatch(){ flag=true; text.setstring(""); Thread th = new Thread(this); th.start(); public void stop(){ flag=false;

23 public void run(){ while(true){ if(flag){ count++; try{ int ms=count%10; int s=count/10%60; int m = s/60%60; int h =m/60; text.setstring(h+""+m+""+s+""+ms); Thread.sleep(100);catch(Exception e){ else break;

Chapter 9: Objects and Classes

Chapter 9: Objects and Classes Java application Java main applet Web applet Runnable Thread CPU Thread 1 Thread 2 Thread 3 CUP Thread 1 Thread 2 Thread 3 ,,. (new) Thread (runnable) start( ) CPU (running) run ( ) blocked CPU sleep(