hellomidlet.java

j2me简单实例,j2me教程加源码,希望大家喜欢

package com.j2medev.chapter2;

import java.io.IOException;
import java.util.TimerTask;
import java.util.Timer;
import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;

public class HelloMIDlet extends MIDlet implements CommandListener {
    
    private Display display = null;
    private Command exitCommand = new Command("Exit",Command.EXIT,1);
    
    public void startApp() {
        //初始化display和MyCanvas对象
        display = Display.getDisplay(this);
        MyCanvas canvas = new MyCanvas();
        canvas.addCommand(exitCommand);
        canvas.setCommandListener(this);
        display.setCurrent(canvas);
    }
    
    public void pauseApp() {
    }
    
    public void destroyApp(boolean unconditional) {
    }
    
    public void commandAction(Command cmd,Displayable displayable){
        if(cmd == exitCommand){
            //退出应用程序
            destroyApp(false);
            notifyDestroyed();
        }
    }
    
    class MyCanvas extends Canvas{
        
        private Timer timer = new Timer();//定时器
        private int x = 10;
        private int y = 10;
        private int width = 0;//画布的宽度
        private int height = 0;//画布的高度
        private Image img = null;
        
        public MyCanvas(){
            width = getWidth();
            height = getHeight();
            try{
                img = Image.createImage("/helloworld.png");
            }catch(IOException ex){
                ex.printStackTrace();
            }
        }
        
        public void paint(Graphics g){
//#if SonyEricsson_K700_Emu || A780
//#             int color = g.getColor();
//#             g.setColor(0xFFFFFF);
//#             g.fillRect(0,0,width,height);
//#             g.setColor(color);
//#else

//#endif
            g.drawImage(img,x,y,Graphics.LEFT|Graphics.TOP);
        }
        
        //当Canvas显示到当前屏幕的时候此方法自动被调用
        public void showNotify(){
            //启动定时器，每100毫秒执行一次
            timer.schedule(new TimerTask(){
                
                private int dx = 2;
                private int dy = 2;
                public static final int SIGN = -1;
                
                public void run(){
                    x = x + dx;
                    y = y + dy;
                    //判断图片是否到达屏幕边界
                    if(x+2+img.getWidth() > width || x-2 < 0)
                        dx = SIGN*dx;
                    if(y + 2 +img.getHeight()> height || y-4 < 0)
                        dy = SIGN*dy;
                    repaint();
                    serviceRepaints();
                }
            },0,100);
        }
        //当Canvas从当前屏幕删除的时候此方法被调用
        public void hideNotify(){
            timer.cancel();
            img = null;
        }
    }
}