activity 监听手势滑动 上下左右

@Override  

    public boolean onTouchEvent(MotionEvent event) {  

        //继承了Activity的onTouchEvent方法，直接监听点击事件  

        if(event.getAction() == MotionEvent.ACTION_DOWN) {  

            //当手指按下的时候  

            x1 = event.getX();  

            y1 = event.getY();  

        }  

        if(event.getAction() == MotionEvent.ACTION_UP) {  

            //当手指离开的时候  

            x2 = event.getX();  

            y2 = event.getY();  

            if(y1 - y2 > 50) {  

                Toast.makeText(MainActivity.this, "向上滑动", Toast.LENGTH_SHORT).show();  

            } else if(y2 - y1 > 50) {  

                Toast.makeText(MainActivity.this, "向下滑动", Toast.LENGTH_SHORT).show();  

            } else if(x1 - x2 > 50) {  

                Toast.makeText(MainActivity.this, "向左滑动", Toast.LENGTH_SHORT).show();  

            } else if(x2 - x1 > 50) {  

                Toast.makeText(MainActivity.this, "向右滑动", Toast.LENGTH_SHORT).show();  

            }  

        }  

        return super.onTouchEvent(event);  

    }