prioritydemo.java

《J2ME图形应用基础》第二章

/*
 * PriorityDemo.java
 *
 * Created on 2005年4月11日, 下午2:47
 */

import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;

/**
 *
 * @author  Liu Bin
 * @version
 */
public class PriorityDemo extends MIDlet implements CommandListener {
    //Display管理
    Display display = null;
    Form form = new Form("线程优先级演示");
    
    Command cmdExit = new Command("退出", Command.STOP, 1);
    Command cmdRun = new Command("同优先级运行", Command.ITEM, 2);
    Command cmdRunHNL = new Command("以高中低优先级运行", Command.ITEM, 2);
    Command cmdRunHLN = new Command("以高低中优先级运行", Command.ITEM, 2);
    Command cmdRunLNH = new Command("以低中高优先级运行", Command.ITEM, 2);
    Command cmdRunNHL = new Command("以中高低优先级运行", Command.ITEM, 2);
    
    MyThreaad p1, p2, p3;
    int[] priorty = {5, 5, 5};
    
    public PriorityDemo() {
        form.addCommand(cmdExit);
        form.addCommand(cmdRun);
        form.addCommand(cmdRunHNL);
        form.addCommand(cmdRunHLN);
        form.addCommand(cmdRunLNH);
        form.addCommand(cmdRunNHL);
        form.setCommandListener(this);
    }
    public void startApp() {
        
        display = Display.getDisplay(this); //获得当前MIDlet的Display对象
        display.setCurrent(form);           //设置form对象为当前显示对象
    }
    
    public void pauseApp() {
    }
    
    public void destroyApp(boolean unconditional) {
        notifyDestroyed();
    }
    
    /**
     * 处理命令按钮事件
     */
    public void commandAction(Command cmd, Displayable d) {
        if (cmd == cmdExit) {
            destroyApp(true);
        } else if (cmd == cmdRun) {
            System.out.println("\n\n==========同优先级测试==========\n");
            this.priorty[0] = Thread.NORM_PRIORITY;
            this.priorty[1] = Thread.NORM_PRIORITY;
            this.priorty[2] = Thread.NORM_PRIORITY;
            runThread();
        } else if (cmd == cmdRunHNL) {
            System.out.println("\n\n========高中低优先级测试==========\n");
            this.priorty[0] = Thread.MAX_PRIORITY;
            this.priorty[1] = Thread.NORM_PRIORITY;
            this.priorty[2] = Thread.MIN_PRIORITY;
            runThread();
        } else if (cmd == cmdRunHLN) {
            System.out.println("\n\n==========高低中优先级测试==========\n");
            this.priorty[0] = Thread.MAX_PRIORITY;
            this.priorty[1] = Thread.MIN_PRIORITY;
            this.priorty[2] = Thread.NORM_PRIORITY;
            runThread();
        } else if (cmd == cmdRunLNH) {
            System.out.println("\n\n==========低中高优先级测试==========\n");
            this.priorty[0] = Thread.MIN_PRIORITY;
            this.priorty[1] = Thread.NORM_PRIORITY;
            this.priorty[2] = Thread.MAX_PRIORITY;
            runThread();
        } else if (cmd == cmdRunNHL) {
            System.out.println("\n\n==========中高低优先级测试==========\n");
            this.priorty[0] = 2;
            this.priorty[1] = Thread.MAX_PRIORITY;
            this.priorty[2] = Thread.MIN_PRIORITY;
            runThread();
        }
    }
    
    void runThread() {
        //创建线程1
        p1 = new MyThreaad(1);
        //设置最低优先级
        p1.setPriority(this.priorty[0]);
        //执行线程1
        p1.start();
        
        //创建线程2
        p2 = new MyThreaad(2);
        //设置普通优先级
        p2.setPriority(this.priorty[1]);
        //执行线程2
        p2.start();
        
        //创建线程3
        p3 = new MyThreaad(3);
        //设置最高优先级
        p3.setPriority(this.priorty[2]);
        //执行线程3
        p3.start();
    }
}


/**
 * 从Thread继承创建线程
 */
class MyThreaad extends Thread {
    //当前线程的ID标识
    long id;
    
    MyThreaad(long id) {
        this.id = id;
    }
    
    public void run() {
        System.out.println("线程"+ id + "开始执行\n");
        
        out(id);
        
        System.out.println("线程"+ id + "执行完毕\n");
    }
    
    static  void out(long id) {
        for (int k = 0; k < 5; k++) {
            int j=0;
            while(j<100000) {
                j++;
            }
            System.out.println("线程"+ id + "，优先级" +
                    Thread.currentThread().getPriority() + "  当前K值: "+ k);
        }
    }
}