Android之Handler的几个例子程序，对比学习

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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);  
        }  
          
    }  
}