handler 更新ui

处理程序  
处理程序的使用（主要更新UI）。 更新 2010年3月9日， 由 平方厘米... @ gmail.com
处理程序使用留言
1，定义一个处理程序

2，重写消息处理函数

（3）发送消息

//创建简单的View
 import android.content.Context;  
 import android.graphics.Canvas;  
 import android.graphics.Color;  
 import android.graphics.Paint;  
 import android.graphics.Point;  
 import android.graphics.drawable.Drawable;  
 import android.view.View;  
   
 public class BounceView extends View {  
     float x = 40;  
       
     public BounceView(Context context) {   
          super(context);   
     }   
   
     @Override   
     protected void onDraw(Canvas canvas) {   
         x+=10;  
         Paint mPaint = new Paint();  
         mPaint.setAntiAlias(true);  
         mPaint.setColor(Color.GREEN);  
         canvas.drawCircle(x, 40, 40, mPaint);  
     }  
 }  

//创建Activity
 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.Message;  
 import android.view.View;  
 import android.view.Window;  
   
 public class TestHandler extends Activity {  
      protected static final int GUIUPDATEIDENTIFIER = 0x101;   
        
      Thread myRefreshThread = null;   
      BounceView myBounceView = null;   
      //1.定义一个Handler(一般更新View)
      Handler myHandler = new Handler() {  
           //2.重写消息处理函数
           public void handleMessage(Message msg) {   
                switch (msg.what) {   
                     //判断发送的消息
                     case TestHandler.GUIUPDATEIDENTIFIER:   
                          //更新View
                          myBounceView.invalidate();  
                          break;   
                }   
                super.handleMessage(msg);   
           }   
      };  
      public void onCreate(Bundle savedInstanceState) {   
           super.onCreate(savedInstanceState);   
           this.requestWindowFeature(Window.FEATURE_NO_TITLE);   
    
           this.myBounceView = new BounceView(this);  
           this.setContentView(this.myBounceView);   
           new Thread(new myThread()).start();  
      }   
    
      class myThread implements Runnable {   
           public void run() {  
                while (!Thread.currentThread().isInterrupted()) {    
                     //3.发送消息
                     Message message = new Message(); 
                     //发送消息与处理函数里一致  
                     message.what = TestHandler.GUIUPDATEIDENTIFIER;   
                     //内部类调用外部类的变量
                     TestHandler.this.myHandler.sendMessage(message);  
 
                     try {   
                          Thread.sleep(100);    
                     } catch (InterruptedException e) {   
                          Thread.currentThread().interrupt();   
                     }   
                }   
           }   
      }   
 }  
利用handler.post（）更新UI
1，创建一个处理程序2。调用Handler.post（Runnable接口R）方法3.Runnable的运行在UI所在线程，所以可以直接调用View.invalidate（）

 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);  
         //创建一个Handler
         mHandler = new Handler();
         //调用Handler.post(Runnable r)方法
         mHandler.post(new Runnable(){  
             @Override  
             public void run() {  
                 //直接调用View.invalidate()，更新组件
                 myView.invalidate();  
                 //延迟5毫秒后执行线程
                 mHandler.postDelayed(this, 5);  
             }  
          });  
         setContentView(myView);  
     }  
       
     class MyView extends View{  
         private float x = 0f;  
         public MyView(Context context) {  
             super(context);  
               
     }  
         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);  
         }  
           
     }  
 }  
在线程里直接更新UI
 //在新线程里更新UI,可以直接使用postInvalidate() 

 public void onCreate(Bundle savedInstanceState) {      
        super.onCreate(savedInstanceState);      
        this.requestWindowFeature(Window.FEATURE_NO_TITLE);      
      
        myView = new MyView(this);  
        this.setContentView(this.myView);      
        new Thread(new myThread()).start();     
 }      
     
 class myThread implements Runnable {      
       public void run() {     
           while (!Thread.currentThread().isInterrupted()) {      
              try {  
                    //更新UI
                    myView.postInvalidate();   
                    Thread.sleep(100);       
               } catch (InterruptedException e) {      
                    Thread.currentThread().interrupt();      
               }      
           }      
       }      
 }