android 手势操作GestureDetector

利用触摸屏的Fling、Scroll等Gesture（手势）操作来操作会使得应用程序的用户体验大大提升，比如用Scroll手势在 浏览器中滚屏，用Fling在阅读器中翻页等。在Android系统中，手势的识别是通过 GestureDetector.OnGestureListener接口来实现的，举例说明：

 

public class ActivityMain extends Activity implements GestureDetector.OnGestureListener { 
 
    GestureDetector detector; 
 
    /** 
     * Called when the activity is first created. 
     */ 
    @Override 
    public void onCreate(Bundle savedInstanceState) { 
        super.onCreate(savedInstanceState); 
        setContentView(R.layout.main); 
        //构造GestureDetector;Context context, OnGestureListener listener 
        detector = new GestureDetector(this, this); 
 
        detector.setOnDoubleTapListener(new GestureDetector.OnDoubleTapListener() { 
           //短快的点击算一次单击 
            @Override 
            public boolean onSingleTapConfirmed(MotionEvent e) { 
                System.out.println("onSingleTapConfirmed"); 
                return false; 
            } 
            //双击时产生一次 
            @Override 
            public boolean onDoubleTap(MotionEvent e) { 
                System.out.println("onDoubleTap"); 
                return false; 
            } 
          //双击时产生两次 
            @Override 
            public boolean onDoubleTapEvent(MotionEvent e) { 
                System.out.println("onDoubleTapEvent"); 
                return false; 
            } 
        }); 
    } 
 
    @Override 
    public boolean onTouchEvent(MotionEvent event) { 
        return detector.onTouchEvent(event); 
    } 
    // 用户轻触触摸屏，由1个MotionEvent ACTION_DOWN触发 
    @Override 
    public boolean onDown(MotionEvent e) { 
        System.out.println("onDown"); 
        return false; 
    } 
  // 用户轻触触摸屏，尚未松开或拖动，由一个1个MotionEvent ACTION_DOWN触发    
   // 注意和onDown()的区别，强调的是没有松开或者拖动的状态 
    @Override 
    public void onShowPress(MotionEvent e) { 
 
    } 
    //用户（轻触触摸屏后）松开，由一个1个MotionEvent ACTION_UP触发 
    @Override 
    public boolean onSingleTapUp(MotionEvent e) { 
        System.out.println("onSingleTapUp"); 
        return false; 
    } 
   // 用户按下触摸屏，并拖动，由1个MotionEvent ACTION_DOWN, 多个ACTION_MOVE触发 
    @Override 
    public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) { 
        System.out.println("onScroll"); 
        return false; 
    } 
   // 用户长按触摸屏，由多个MotionEvent ACTION_DOWN触发 
    @Override 
    public void onLongPress(MotionEvent e) { 
        System.out.println("onLongPress" + e.getEventTime()); 
    } 
   //用户按下触摸屏、快速移动后松开，由1个MotionEvent ACTION_DOWN, 多个ACTION_MOVE, 1个ACTION_UP触发 
    @Override 
    public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) { 
        System.out.println("onFling: " + (e1.getX() - e2.getX()) + " " + (e1.getY() - e2.getY()) + " " + velocityX + " " + velocityY); 
        System.out.println(e1.getY()); 
        return false; 
    } 
}