Android中EditText的drawableRight属性设置点击事件

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:tools="http://schemas.android.com/tools"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:paddingBottom="@dimen/activity_vertical_margin"
  android:paddingLeft="@dimen/activity_horizontal_margin"
  android:paddingRight="@dimen/activity_horizontal_margin"
  android:paddingTop="@dimen/activity_vertical_margin"
  tools:context="com.example.drablerighttest.MainActivity" >

  <EditText
    android:id="@+id/et"
    android:layout_width="350dp"
    android:layout_height="wrap_content"
    android:drawableRight="@drawable/search_clear_pressed"
    android:text="@string/hello_world" />

</RelativeLayout>

public class MainActivity extends Activity {

  private EditText et;

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    et = (EditText) this.findViewById(R.id.et);
    et.setOnTouchListener(new OnTouchListener() {

      @Override
      public boolean onTouch(View v, MotionEvent event) {
        // et.getCompoundDrawables()得到一个长度为4的数组，分别表示左右上下四张图片
        Drawable drawable = et.getCompoundDrawables()[2];
        //如果右边没有图片，不再处理
        if (drawable == null)
          return false;
        //如果不是按下事件，不再处理
        if (event.getAction() != MotionEvent.ACTION_UP)
          return false;
        if (event.getX() > et.getWidth()
            - et.getPaddingRight()
            - drawable.getIntrinsicWidth()){
          et.setText("");
        }
          return false;
      }
    });
  }
}