http://blog.csdn.net/ganlijianstyle/article/details/7490700

postInvalidate() ,Invalidate() 區別

postInvalidate() 用在子執行緒向UI執行緒傳送介面重新整理訊息請求，

invalidate()呼叫直接在UI執行緒重新整理介面。

第１種情況　postInvalidate();

第２種情況　invalidate();　根據handler 收到的訊息，對介面進行重繪

package com.ganstyle.activity;


import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Paint.Style;
import android.os.Handler;
import android.os.Message;
import android.util.Log;
import android.view.KeyEvent;
import android.view.MotionEvent;
import android.view.View;




public class HandleGameView extends View{
private Paint paint=null;
private int x;
    private Handler handler = new  Handler()
    {

@Override

public void handleMessage(Message msg) {

if(msg.what == 1)

{

           　　　　　　　 invalidate();

　　}

Log.i("Handler", String.valueOf(Thread.currentThread().getId()));

}

public HandleGameView(Context context) {
super(context);
paint = new Paint();
paint.setColor(Color.GREEN);
paint.setStyle(Style.STROKE);
this.setFocusable(true);

}




@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.drawLine(0,0,400, 0, paint);
canvas.drawLine(x,0,x, 400, paint);
Log.i("onDraw", String.valueOf(Thread.currentThread().getId()));
}
MyThread t=null;
@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {

// while (x<300)
//       {
//   x++;
//             GameView.this.postInvalidate();
//         }      執行這個不會在主執行緒重繪


switch (keyCode){
case  KeyEvent.KEYCODE_DPAD_CENTER:
           if(t==null||x<300)
     {
t= new MyThread();
    t.start(); 
}System.out.println("GameView "+ keyCode ); 
 //設定 返回鍵 生效　
 case  KeyEvent.KEYCODE_BACK:
return super.onKeyDown(keyCode, event); 
default :
break;
}
//return super.onKeyDown(keyCode, event); 
return true; //設定為true,表示不向下面的元件或View傳遞
}




@Override
public boolean onTouchEvent(MotionEvent event) {
    //event.getAction 得到三種事件　 0　代表獲得焦點、1代表離開螢幕、2代表按著螢幕　
System.out.println("GameView "+ event.getX()+"  "+event.getY()+" event type "+event.getAction()); 
Log.i("onTouchEvent", String.valueOf(Thread.currentThread().getId()));
x =(int) event.getX();
//return super.onTouchEvent(event);
return true; //設定為true,表示不向下面的元件或View傳遞
}

private class MyThread extends Thread{
@Override
public void run() {
// TODO Auto-generated method stub
           while (x<300)
           {
   x++;
   
               try {
Thread.sleep(200);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
           Log.i("MyThread", String.valueOf(Thread.currentThread().getId()));
             Message message = new Message();
             message.what = 1;
             handler.sendMessage(message);
               
           }}
   
}

}