获取GridView点击空白处事件

public class XGridView extends GridView {

    private GestureDetector gestureDetector;

    public XGridView(Context context, AttributeSet attrs) {
        super(context, attrs);
        init(context);
    } 

    public XGridView(Context context) { 
        super(context);
        init(context);
    } 

    public XGridView(Context context, AttributeSet attrs, int defStyle) { 
        super(context, attrs, defStyle);
        init(context);
    }

    private void init(Context context) {
        gestureDetector = new GestureDetector(context,new MSimpleOnGestureListener());
    }

    @Override 
    public void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { 

        int expandSpec = MeasureSpec.makeMeasureSpec( 
                Integer.MAX_VALUE >> 2, MeasureSpec.AT_MOST); 
        super.onMeasure(widthMeasureSpec, expandSpec); 
    }


    @Override
    public boolean onTouchEvent(MotionEvent event) {
        if (mTouchBlankPosListener != null) {
            if (!isEnabled()) {
                return isClickable() || isLongClickable();
            }
            int action = event.getActionMasked();
            float x = event.getX();
            float y = event.getY();
            int motionPosition = pointToPosition((int) x, (int) y);
            if (motionPosition == INVALID_POSITION) {
                gestureDetector.onTouchEvent(event);
            }
        }
        return super.onTouchEvent(event);
    }
     private OnTouchBlankPositionListener mTouchBlankPosListener;
    /**
     * 设置GridView的空白区域的触摸事件
     *
     * @param listener
     */
    public void setOnTouchBlankPositionListener(
            OnTouchBlankPositionListener listener) {
        mTouchBlankPosListener = listener;
    }

    public interface OnTouchBlankPositionListener {
        void onTouchBlank(MotionEvent event);
    }


    public class MSimpleOnGestureListener extends GestureDetector.SimpleOnGestureListener{

        @Override
        public boolean onSingleTapUp(MotionEvent e) {
                mTouchBlankPosListener.onTouchBlank(e);
            return super.onSingleTapUp(e);
        }
    }
}