Android setOnTouchListener识别滑动手势

setOnTouchListener(new OnTouchListener() {
            private float startX, startY, offsetX, offsetY;

            @Override
            public boolean onTouch(View v, MotionEvent event) {
                switch (event.getAction()) {
                case MotionEvent.ACTION_DOWN:
                    startX = event.getX();
                    startY = event.getY();
                    break;
                case MotionEvent.ACTION_UP:
                    offsetX = event.getX() - startX;
                    offsetY = event.getY() - startY;
                    if (Math.abs(offsetX) > Math.abs(offsetY)) {
                        if (offsetX < -5) { // left
                            swipeLeft();
                        } else if (offsetX > 5) { // right
                            swipeRight();
                        }
                    } else {
                        if (offsetY < -5) { // up
                            swipeUp();
                        } else if (offsetY > 5) { // down
                            swipeDown();
                        }
                    }
                    break;
                default:
                    break;
                }
                return true;
            }
        });