GestureDetector（手势识别器） ### （1）手势交互过程原理： A.触屏一刹那，触发 MotionEvent事件； B.上述事件被 OnTouchListenter 监听，在 nTouch() 中获得 MotionEvent对象； C.GestureDetector 转发MotionEvent对象至 OnGestureListenter； D.OnGestureListenter 获得该对象，根据该对象封装的信息作出合适的反馈； ### （2）MotionEvent： 1）、用于封装手势等动作事件； 2）、内部封装用于记录横轴和纵轴坐标的属性X和Y； GestureDetector： 1）、识别各种手势； OnGestureListenter： 1）、手势交互的监听接口，其提供多个抽象方法； 2）、根据GestureDetector的手势识别结果调用相对应的方法； ### （3）GestureDetector工作原理： 1)、GestureDetector.OnGestureListener接口 onDown(MotionEvent e)：——单击 Notified when a tap occurs with the down MotionEvent that triggered it. onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY)：——滑动 Notified of a fling event when it occurs with the initial on down MotionEvent and the matching up MotionEvent. onLongPress(MotionEvent e)：——长按 Notified when a long press occurs with the initial on down MotionEvent that trigged it. onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY)：——滚动 Notified when a scroll occurs with the initial on down MotionEvent and the current move MotionEvent. onShowPress(MotionEvent e)：——短按 The user has performed a down MotionEvent and not performed a move or up yet. onSingleTapUp(MotionEvent e)：——抬起 Notified when a tap occurs with the up MotionEvent that triggered it.  2)、GestureDetector.OnDoubleTapListener接口 onDoubleTap(MotionEvent e)：——双击** Notified when a double-tap occurs. onDoubleTapEvent(MotionEvent e)：——双击按下和抬起各触发一次 Notified when an event within a double-tap gesture occurs, including the down, move, and up events. onSingleTapConfirmed(MotionEvent e)：——单击确认（即很快的按下并抬起，但并不连续点击第二下） Notified when a single-tap occurs. 3）、GestureDetector.SimpleOnGestureListener类 其实我们并不需要处理上面所有手势。问了方便起见，Android提供了另外一个类SimpleOnGestureListener。它实现了如上接口，我们只需要继承SimpleOnGestureListener类，然后重载感兴趣的手势。 implements [GestureDetector.OnGestureListener](http://developer.android.com/reference/android/view/GestureDetector.OnGestureListener.html) [GestureDetector. OnDoubleTapListener](http://developer.android.com/reference/android/view/GestureDetector.OnDoubleTapListener.html)[GestureDetector. OnContextClickListener](http://developer.android.com/reference/android/view/GestureDetector.OnContextClickListener.html)。A convenience class to extend when you only want to listen for a subset of all the gestures. This implements all methods in  the  `[GestureDetector.OnGestureListener](http://developer.android.com/reference/android/view/GestureDetector.OnGestureListener.html)`,  `[GestureDetector.OnDoubleTapListener](http://developer.android.com/reference/android/view/GestureDetector.OnDoubleTapListener.html)`, and`[GestureDetector.OnContextClickListener](http://developer.android.com/reference/android/view/GestureDetector.OnContextClickListener.html)` but does nothing and return`false` for all applicable methods. ~~~ public class MainActivity extends Activity { private ImageView imageView; private GestureDetector mygestureDetector; // 继承SimpleOnGestureListener类，然后重载感兴趣的手势。 class MyGestureListenter extends SimpleOnGestureListener { @Override // 重载滑动手势 public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) { if (e1.getX() - e2.getX() > 50) { Toast.makeText(MainActivity.this, "从右往左滑动", Toast.LENGTH_SHORT) .show(); } else if (e2.getX() - e1.getX() > 50) { Toast.makeText(MainActivity.this, "从左往右滑动", Toast.LENGTH_SHORT) .show(); } return super.onFling(e1, e2, velocityX, velocityY); } } @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); /* * GestureDetector工作原理 * 1、当接收到用户触摸消息时，将消息交给GestureDetector加工； * 2、通过设置监听器获得GestureDetector处理后的手势； * 3、GestureDetector提供两个监听器： * A.OnGestureListenter：处理单击类消息； * B.OnDoubleTapListenter：处理双击类消息； */ imageView = (ImageView) findViewById(R.id.img); mygestureDetector = new GestureDetector(new MyGestureListenter()); // MotionEvent——》setOnTouchListener捕获 // ——》onTouch中GestureDetector对象将监听事件转发给MyGestureListenter(extends SimpleOnGestureListener) // ——》MyGestureListenter类中实现了要重载的手势 imageView.setOnTouchListener(new OnTouchListener() { @Override // 可以捕获触摸屏幕发生的Event public boolean onTouch(View v, MotionEvent event) { // TODO Auto-generated method stub mygestureDetector.onTouchEvent(event); // 转发event事件，转发给MyGestureListenter(extends SimpleOnGestureListener) return false; } }); } //消除冲突 /*@Override public boolean dispatchTouchEvent(MotionEvent ev) { // TODO Auto-generated method stub if(mygestureDetector!=null){ if(mygestureDetector.onTouchEvent(ev)){ return true; } } return super.dispatchTouchEvent(ev); }*/ //必须重写onTouchEvent方法，onFling才生效 @Override public boolean onTouchEvent(MotionEvent event) { // TODO Auto-generated method stub return mygestureDetector.onTouchEvent(event); } } ~~~ 为了让onFling才生效，必须重写onTouchEvent方法！