handler机制分析

private Handler handler;
 private Looper looper;
 
 private Thread myThread=new Thread()
 {
  public void run()
  {
   Looper.prepare();
   looper=Looper.myLooper();
   handler=new Handler(looper)
   {
    @Override
    public void handleMessage(Message msg)
    {
     Log.d("test","what="+msg.what);
    }
   };
handler2=new Handler(looper,new Handler.Callback()
   {
    @Override
    public boolean handleMessage(Message msg)
    {
     Log.d("test","what2="+msg.what);
     return false;
    }
   });
   Looper.loop();
  }
 };

Button btn=(Button)findViewById(R.id.stop_btn);
btn.setOnClickListener(new OnClickListener()
        {
   @Override
   public void onClick(View v)
   {
    if(flag)
    {
     looper.quit();
    }else{
    }
   }
});