Android 点击ImageButton时有“按下”的效果的实现

imageButton.setOnTouchListener(new OnTouchListener(){               @Override              public boolean onTouch(View v, MotionEvent event) {                   if(event.getAction() == MotionEvent.ACTION_DOWN){                       //更改为按下时的背景图片                       v.setBackgroundResource(R.drawable.pressed);                   }else if(event.getAction() == MotionEvent.ACTION_UP){                       //改为抬起时的图片                       v.setBackgroundResource(R.drawable.released);                   }                   return false;               }           });  

<?xml version="1.0" encoding="UTF-8"?>  <selector xmlns:android="http://schemas.android.com/apk/res/android">    <item android:state_pressed="false" android:drawable="@drawable/button_add" />    <item android:state_pressed="true"  android:drawable="@drawable/button_add_pressed" />    <item android:state_focused="true"  android:drawable="@drawable/button_add_pressed" />    <item android:drawable="@drawable/button_add" />  </selector>