Android屏幕手势检测的实现代码

package com.fukaimei.gesturedetector;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.GestureDetector;
import android.view.MotionEvent;
import android.widget.TextView;
import com.fukaimei.gesturedetector.util.DateUtil;
public class GestureDetectorActivity extends AppCompatActivity {
  private TextView tv_gesture;
  private GestureDetector mGesture;
  private String desc = "";
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_gesture_detector);
    tv_gesture = (TextView) findViewById(R.id.tv_gesture);
    mGesture = new GestureDetector(this, new MyGestureListener());
  }
  public boolean dispatchTouchEvent(MotionEvent event) {
    mGesture.onTouchEvent(event);
    return true;
  }
  final class MyGestureListener implements GestureDetector.OnGestureListener {
    @Override
    public final boolean onDown(MotionEvent event) {
//     desc = String.format("%s%s 您按下来了\n", desc, DateUtil.getNowTime());
//     tv_gesture.setText(desc);
      //onDown的返回值没有作用，不影响其它手势的处理
      return true;
    }
    @Override
    public final boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
      float offsetX = e1.getX() - e2.getX();
      float offsetY = e1.getY() - e2.getY();
      if (Math.abs(offsetX) > Math.abs(offsetY)) {
        if (offsetX > 0) {
          desc = String.format("%s%s 您向左滑动了一下\n", desc, DateUtil.getNowTime());
        } else {
          desc = String.format("%s%s 您向右滑动了一下\n", desc, DateUtil.getNowTime());
        }
      } else {
        if (offsetY > 0) {
          desc = String.format("%s%s 您向上滑动了一下\n", desc, DateUtil.getNowTime());
        } else {
          desc = String.format("%s%s 您向下滑动了一下\n", desc, DateUtil.getNowTime());
        }
      }
      tv_gesture.setText(desc);
      return true;
    }
    @Override
    public final void onLongPress(MotionEvent event) {
      desc = String.format("%s%s 您长按了一下下\n", desc, DateUtil.getNowTime());
      tv_gesture.setText(desc);
    }
    @Override
    public final boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
      return false;
    }
    @Override
    public final void onShowPress(MotionEvent event) {
    }
    @Override
    public boolean onSingleTapUp(MotionEvent event) {
      desc = String.format("%s%s 您轻轻点了一下\n", desc, DateUtil.getNowTime());
      tv_gesture.setText(desc);
      //返回true表示我已经处理了，别处不要再处理这个手势
      return true;
    }
  }
}