利用Handler更新Android UI的另一种方法

其实文字游戏程序很简单，就是一个view和一个Activity，在利用下handier和postInvalidate()更新UI
我要实现的是一个蓝色正方形向右移出屏

 

调用Handler.post(Runnable r)方法,Runnable运行在UI所在线程,所以可以直接调用View.invalidate()

   
     

    
      
    
       1 
    
      package
    
       com.Test.androidtest; 

    
       2 
    
       

    
       3 
    
       
    
      import
    
       android.app.Activity; 

    
       4 
    
       
    
      import
    
       android.content.Context; 

    
       5 
    
       
    
      import
    
       android.graphics.Canvas; 

    
       6 
    
       
    
      import
    
       android.graphics.Color; 

    
       7 
    
       
    
      import
    
       android.graphics.Paint; 

    
       8 
    
       
    
      import
    
       android.os.Bundle; 

    
       9 
    
       
    
      import
    
       android.os.Handler; 

    
      10 
    
      
    
      import
    
       android.view.View; 

    
      11 
    
       

    
      12 
    
      
    
      public
    
       
    
      class
    
       TestHandler 
    
      extends
    
       Activity { 

    
      13 
    
       
    
      private
    
       MyView myView; 

    
      14 
    
       
    
      private
    
       Handler mHandler; 

    
      15 
    
       
    
      public
    
       
    
      void
    
       onCreate(Bundle savedInstanceState) { 

    
      16 
    
       
    
      super
    
      .onCreate(savedInstanceState); 

    
      17 
    
       myView 
    
      =
    
       
    
      new
    
       MyView(
    
      this
    
      ); 

    
      18 
    
       mHandler 
    
      =
    
       
    
      new
    
       Handler(); 

    
      19 
    
       mHandler.post(
    
      new
    
       Runnable(){ 

    
      20 
    
       @Override 

    
      21 
    
       
    
      public
    
       
    
      void
    
       run() { 

    
      22 
    
       myView.invalidate(); 

    
      23 
    
       mHandler.postDelayed(
    
      this
    
      , 
    
      5
    
      ); 

    
      24 
    
       } 

    
      25 
    
       }); 

    
      26 
    
       setContentView(myView); 

    
      27 
    
       } 

    
      28 
    
       

    
      29 
    
       
    
      class
    
       MyView 
    
      extends
    
       View{ 

    
      30 
    
       
    
      private
    
       
    
      float
    
       x 
    
      =
    
       0f; 

    
      31 
    
       
    
      public
    
       MyView(Context context) { 

    
      32 
    
       
    
      super
    
      (context); 

    
      33 
    
       

    
      34 
    
       } 

    
      35 
    
       
    
      protected
    
       
    
      void
    
       onDraw(Canvas canvas) { 

    
      36 
    
       
    
      super
    
      .onDraw(canvas); 

    
      37 
    
       x
    
      +=
    
      1
    
      ; 

    
      38 
    
       Paint mPaint 
    
      =
    
       
    
      new
    
       Paint(); 

    
      39 
    
       mPaint.setColor(Color.BLUE); 

    
      40 
    
       canvas.drawRect(x, 
    
      40
    
      , x
    
      +
    
      40
    
      , 
    
      80
    
      , mPaint); 

    
      41 
    
       } 

    
      42 
    
       

    
      43 
    
       } 

    
      44 
    
      } 

    
      45 
    
      
   
     

 

在新线程里更新UI,可以直接postInvalidate()

 

   
     

    
      
    
       1 
    
      public
    
       
    
      void
    
       onCreate(Bundle savedInstanceState) { 

    
       2 
    
       
    
      super
    
      .onCreate(savedInstanceState); 

    
       3 
    
       
    
      this
    
      .requestWindowFeature(Window.FEATURE_NO_TITLE); 

    
       4 
    
       

    
       5 
    
       myView 
    
      =
    
       
    
      new
    
       MyView(
    
      this
    
      ); 

    
       6 
    
       
    
      this
    
      .setContentView(
    
      this
    
      .myView); 

    
       7 
    
       
    
      new
    
       Thread(
    
      new
    
       myThread()).start(); 

    
       8 
    
      } 

    
       9 
    
       

    
      10 
    
       
    
      class
    
       myThread 
    
      implements
    
       Runnable { 

    
      11 
    
       
    
      public
    
       
    
      void
    
       run() { 

    
      12 
    
       
    
      while
    
       (
    
      !
    
      Thread.currentThread().isInterrupted()) { 

    
      13 
    
       
    
      try
    
       { 

    
      14 
    
       myView.postInvalidate(); 

    
      15 
    
       Thread.sleep(
    
      100
    
      ); 

    
      16 
    
       } 
    
      catch
    
       (InterruptedException e) { 

    
      17 
    
       Thread.currentThread().interrupt(); 

    
      18 
    
       } 

    
      19 
    
       } 

    
      20 
    
       } 

    
      21 
    
       } 

    
      22