GestureDetector 手势

private GestureDetector gestureDetector;//声明手势全局变量
gestureDetector = new GestureDetector(this, onGestureListener);//初始化该变量
//    允许你的活动(Activity)可以在分发给窗口之前捕获所有的触摸事件。
    @Override
    public boolean dispatchTouchEvent(MotionEvent ev) {
    gestureDetector.onTouchEvent(ev);
    return super.dispatchTouchEvent(ev);
    }
public boolean onTouchEvent(MotionEvent event) {
        return gestureDetector.onTouchEvent(event);//重写触摸事件，用手势事件来响应触摸事件
    }
GestureDetector.OnGestureListener onGestureListener = new GestureDetector.SimpleOnGestureListener() {//这是定义好的手势事件
        public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {//这个方法中在判断手势怎么滑动
           
            float slipping_x = e2.getX() - e1.getX();
            float slipping_x_abs = Math.abs(slipping_x);//求绝对值
            if (slipping_x_abs < 100) {//判断滑动的最小距离
                return false;
            }
            if (slipping_x > 0) {//大于0，说明左滑
            flipper.setInAnimation(MainActivity.this, R.anim.push_left_in);
flipper.setOutAnimation(MainActivity.this,R.anim.push_left_out);
flipper.showNext();

            } else if (slipping_x < 0) {//小于0，说明右滑
            flipper.setInAnimation(MainActivity.this, R.anim.push_right_in);
flipper.setOutAnimation(MainActivity.this,R.anim.push_right_out);
flipper.showPrevious();
            }
        
            return true;
        }

    };