关于handler 信息接收 问题。。。。。

Question

[code="java"]

package com.rock;

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.os.Looper;
import android.os.Message;
import android.util.AttributeSet;
import android.view.View;

public class RockActivity extends Activity {
/*

• 动态图形的绘制基本思路是，创建一个类继承View(或surfaceView)覆盖
• onDraw()方法，使用 Canvas对象在界面上绘制不同的图形，使用invalidate()

• 方法刷新界面 。下面是一个弹球实例 运用动态图形绘制基本思路。
  */

  public void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.main);

  RockView rockView=new RockView(this, null);
  setContentView(rockView);
  

  }

  class RockView extends View implements Runnable{

  private int x=20,y=20;
  
  protected void onDraw(Canvas canvas) {
  
      //实例化画笔
      Paint paint=new Paint();
      //设置画笔颜色
      paint.setColor(Color.GREEN);
  
      canvas.drawCircle(x, y, 10, paint);
      super.onDraw(canvas);
  }
  
  public RockView(Context context, AttributeSet attrs) {
  
      super(context, attrs);
      //获得焦点
      setFocusable(true);
      new Thread(this).start();
  }
  
  /*
   *E/AndroidRuntime( 4582): java.lang.RuntimeException:
   * Can't create handler inside thread that has not called Looper.prepare()
   * 
   * 解决方法之一 在 run()方法 前 加Looper.prepare() 末尾 加Looper.loop();
   */
  public void run() {
      Looper.prepare();
      RefreshHandler refreshHandler=new RefreshHandler();
  
      while(!(Thread.currentThread().isInterrupted())){
  
          Message msg=new Message();
          msg.what=0x101;
          refreshHandler.sendMessage(msg);
  
          try {
              Thread.sleep(500);
          } catch (InterruptedException e) {
              e.printStackTrace();
          }
      }
      Looper.loop();
  }
  
  class RefreshHandler extends Handler{
  
      public void handleMessage(Message msg) {        
  
          if(msg.what==0x101){
               RockView.this.update();
               RockView.this.invalidate();
          }
              super.handleMessage(msg);
          }
  
  }
  private void update(){
      int height=getHeight();
      y+=5;
      if(y>=height){
          y=20;
      }
  }
  

  }
  }

[/code]

这个 handler数据可以发送，为什么 接受不了呢？ 求指教

Answer 1

[code="java"]
public class RockActivity extends Activity {

/*

• 动态图形的绘制基本思路是，创建一个类继承View(或surfaceView)覆盖
• onDraw()方法，使用 Canvas对象在界面上绘制不同的图形，使用invalidate()

• 方法刷新界面 。下面是一个弹球实例 运用动态图形绘制基本思路。
  */
  
  private RefreshHandler refreshHandler = null;
  private RockView rockView = null;
  public void onCreate(Bundle savedInstanceState) {
  
  super.onCreate(savedInstanceState);
  
  setContentView(R.layout.main);
  
  refreshHandler = new RefreshHandler() ;
  rockView=new RockView(this, null);
  
  setContentView(rockView);
  
  }

  class RockView extends View implements Runnable{

   private int x=20,y=20;  
  
   protected void onDraw(Canvas canvas) {  
  
       //实例化画笔  
       Paint paint=new Paint();  
       //设置画笔颜色  
       paint.setColor(Color.GREEN);  
  
       canvas.drawCircle(x, y, 10, paint);  
       super.onDraw(canvas);  
   }  
  
   public RockView(Context context, AttributeSet attrs) {  
  
       super(context, attrs);  
       //获得焦点  
       setFocusable(true);  
       new Thread(this).start();  
   }  
  
   /* 
    *E/AndroidRuntime( 4582): java.lang.RuntimeException: 
    * Can't create handler inside thread that has not called Looper.prepare() 
    *  
    * 解决方法之一 在 run()方法 前 加Looper.prepare() 末尾 加Looper.loop(); 
    */  
   public void run() {  
       Looper.prepare();  
      // RefreshHandler refreshHandler=new RefreshHandler();  
       while(!(Thread.currentThread().isInterrupted())){  
           Message msg=new Message();  
           msg.what=0x101;  
           refreshHandler.sendMessage(msg); 
           try {  
               Thread.sleep(500);  
           } catch (InterruptedException e) {  
               e.printStackTrace();  
           }  
       }  
       Looper.loop();  
   }  
  
   private void update(){  
       int height=getHeight();  
       y+=5;  
       if(y>=height){  
           y=20;  
       }  
   }  
  

  }
  
  /*--class refreshHandler--*/
  class RefreshHandler extends Handler{

   public void handleMessage(Message msg) {          
  
       if(msg.what==0x101){  
           rockView.update();  
           rockView.invalidate();  
       }  
           super.handleMessage(msg);  
       }  
  

  }
  
  /*--class refreshHandler--*/
  }
  [/code]
  这个改好了 在主线程中创建接收消息的handler，然后在方法里面更新RockView对象，全局变量