利用Handler更新Android UI的另一种方法

文字程序很简单，一个View，一个Activity，利用handler和postInvalidate()更新UI。
程序效果是一个蓝色的正方形向右移出屏幕。
Java代码
package com.ray.test;  
 
import android.app.Activity;  
import android.content.Context;  
import android.graphics.Canvas;  
import android.graphics.Color;  
import android.graphics.Paint;  
import android.os.Bundle;  
import android.os.Handler;  
import android.view.View;  
 
public class TestHandler extends Activity {  
    private MyView myView;  
    private Handler mHandler;  
    public void onCreate(Bundle savedInstanceState) {  
        super.onCreate(savedInstanceState);  
        myView = new MyView(this);  
        mHandler = new Handler();  
        mHandler.post(update);  
        setContentView(myView);  
    }  
      
    private Runnable update = new Runnable() {  
        public void run() {  
            myView.update();  
            mHandler.postDelayed(update, 5);  
        }  
    };  
      
    class MyView extends View{  
          
        private float x = 0f;  
        public MyView(Context context) {  
            super(context);  
              
        }  
          
        public void update(){  
            postInvalidate();  
        }  
        protected void onDraw(Canvas canvas) {  
            super.onDraw(canvas);  
            x+=1;  
            Paint mPaint = new Paint();  
            mPaint.setColor(Color.BLUE);  
            canvas.drawRect(x, 40, x+40, 80, mPaint);  
        }  
          
    }  
} 

package com.ray.test;

import android.app.Activity;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.os.Bundle;
import android.os.Handler;
import android.view.View;

public class TestHandler extends Activity {
        private MyView myView;
        private Handler mHandler;
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        myView = new MyView(this);
        mHandler = new Handler();
        mHandler.post(update);
        setContentView(myView);
    }
   
    private Runnable update = new Runnable() {
        public void run() {
            myView.update();
            mHandler.postDelayed(update, 5);
        }
    };
   
    class MyView extends View{
           
            private float x = 0f;
                public MyView(Context context) {
                        super(context);
                       
                }
               
                public void update(){
                        postInvalidate();
                }
                protected void onDraw(Canvas canvas) {
                        super.onDraw(canvas);
                        x+=1;
                        Paint mPaint = new Paint();
                        mPaint.setColor(Color.BLUE);
                        canvas.drawRect(x, 40, x+40, 80, mPaint);
                }
           
    }
} 之前还写过另外一篇关于Handler更新UI的文章：
http://rayleung.iteye.com/blog/411860