android 判断手指滑动方向

private float downX, downY;

    private final float SLIDE_ANGLE = 45;

    private boolean mIsSlideHorizontally;//是否是水平滑动

    @Override

    public boolean dispatchTouchEvent(MotionEvent ev) {

        switch (ev.getAction()) {

        case MotionEvent.ACTION_DOWN:

            downX = ev.getX();

            downY = ev.getY();

            break;

        case MotionEvent.ACTION_MOVE:

        case MotionEvent.ACTION_UP:

            float moveX = ev.getX();

            float moveY = ev.getY();

            float xDiff = Math.abs(moveX - downX);

            float yDiff = Math.abs(moveY - downY);

            double squareRoot = Math.sqrt(xDiff * xDiff + yDiff * yDiff);

            //滑动的角度

            int yAngle = Math.round((float) (Math.asin(yDiff / squareRoot) / Math.PI * 180));

            int xAngle = Math.round((float) (Math.asin(xDiff / squareRoot) / Math.PI * 180));

            boolean isMeetSlidingYAngle = yAngle > SLIDE_ANGLE;//滑动角度是否大于45du

            boolean isMeetSlidingXAngle = xAngle > SLIDE_ANGLE;//滑动角度是否大于45du

            boolean isSlideUp = moveY < downY && isMeetSlidingYAngle;

            boolean isSlideDown = moveY > downY && isMeetSlidingYAngle;

            boolean isSlideLeft = moveX < downX && isMeetSlidingXAngle;

            boolean isSlideRight = moveX > downX && isMeetSlidingXAngle;

            if (isSlideUp) {

                Log.d("chenhaocc", "向上滑动");

                mIsSlideHorizontally = false;

            } else if (isSlideDown) {

                Log.d("chenhaocc", "向下滑动");

                mIsSlideHorizontally = false;

            } else if (isSlideLeft) {

                Log.d("chenhaocc", "向左边滑动");

                mIsSlideHorizontally = true;

            } else if (isSlideRight) {

                mIsSlideHorizontally = true;

                Log.d("chenhaocc", "向右边滑动");

            }

        }

        return super.dispatchTouchEvent(ev);

    }