j2me学习十_MIDP2.0学习

 GameCanvas及Sprite类的使用

import javax.microedition.lcdui.Graphics;
import javax.microedition.lcdui.Image;
import javax.microedition.lcdui.game.GameCanvas;
import javax.microedition.lcdui.game.Sprite;

public class MyGameCanvas extends GameCanvas implements Runnable {
 static final int UP=0;
 static final int DOWN=1;
 static final int LEFT=2;
 static final int RIGHT=3;
 int aup[]={12,12,13,13,14,14,15};
 int adown[]={0,1,2,3};
 int aleft[]={4,4,5,5,6,6,7,7};
 int aright[]={8,9,10,11};
 int mSpeed=5;
 int mDir=0;
 private boolean RUN=true;
 private Graphics g;
 private Sprite mHero;
 private Image img;
 public MyGameCanvas()
 {
  super(true);
  g=this.getGraphics();
  try {
   img=Image.createImage("/hero.png");
   
  } catch (Exception e) {
   // TODO: handle exception
   e.printStackTrace();
  }
  
  mHero=new Sprite(img,32,48);
  System.out.println("执行到我了");
  mHero.setPosition(20, 50);
  new Thread(this).start();
 }
 public void moveto(int dir) {
  // TODO Auto-generated method stub
  switch(dir){
  case UP:
   if(dir!=mDir)
    mHero.setFrameSequence(aup);
    mHero.move(0, -mSpeed);
    break;
  case DOWN:
   if(dir!=mDir)
    mHero.setFrameSequence(adown);
   mHero.move(0, mSpeed);
   break;
  case LEFT:
   if(dir!=mDir)
    mHero.setFrameSequence(aleft);
   mHero.move(-mSpeed, 0);
   break;
  case RIGHT:
   if(dir!=mDir)
    mHero.setFrameSequence(aright);
   mHero.move(mSpeed, 0);
   break;
  }
  mDir=dir;
  mHero.nextFrame();
 }
 public void handleKey(){
  int key=getKeyStates();
  if((key&UP_PRESSED)!=0) moveto(UP);
  if((key&DOWN_PRESSED)!=0) moveto(DOWN);
  if((key&LEFT_PRESSED)!=0) moveto(LEFT);
  if((key&RIGHT_PRESSED)!=0) moveto(RIGHT);
 }
 public void run() {
  while (RUN) {
   try {
    g.setColor(0);
    g.fillRect(0, 0, this.getWidth(), this.getHeight());
    handleKey();
    mHero.paint(g);
    this.flushGraphics();/**/
    Thread.sleep(100);
    
   } catch (Exception e) {
    // TODO: handle exception
   }
   
  }
  
 }
}
运行使用的效果是人物精灵的行走。
终于知道怎么去调试j2me项目了。。。。
在运行过程中，Console窗口中会出调试信息，可以根据信息去debug，
例如，当我运行到这一步的时候，
mHero=new Sprite(img,32,40);
意外中断了，抛出异常IllegalArgumentException，
查看文档，原来是尺寸不匹配，修改一下，编译通过~