重写recyclerview中ontouchevent

我不知道具体情况，但是重写 RecyclerView 中的 onTouchEvent 通常是为了实现一些特殊的触摸行为，比如滑动删除、拖拽排序等。以下是可能的一些代码实现：

1. 滑动删除

@Override
public boolean onTouchEvent(MotionEvent e) {
    switch (e.getAction()) {
        case MotionEvent.ACTION_DOWN:
            mIsSwiping = false;
            mDownX = e.getX();
            mDownY = e.getY();
            return super.onTouchEvent(e);
        case MotionEvent.ACTION_MOVE:
            float dx = e.getX() - mDownX;
            float dy = e.getY() - mDownY;
            if (Math.abs(dx) > mTouchSlop && Math.abs(dy) < mTouchSlop) {
                mIsSwiping = true;
                int position = getChildAdapterPosition(findChildViewUnder(e.getX(), e.getY()));
                if (position != RecyclerView.NO_POSITION) {
                    mSwipePosition = position;
                }
            }
            return super.onTouchEvent(e);
        case MotionEvent.ACTION_UP:
        case MotionEvent.ACTION_CANCEL:
            if (mIsSwiping) {
                if (dx > 0) {
                    // swiped right, perform delete action
                    mAdapter.deleteItem(mSwipePosition);
                } else {
                    // swiped left, reset item view
                    mAdapter.notifyItemChanged(mSwipePosition);
                }
                mIsSwiping = false;
                mSwipePosition = RecyclerView.NO_POSITION;
                return true;
            }
            return super.onTouchEvent(e);
    }
    return super.onTouchEvent(e);
}

2. 拖拽排序

@Override
public boolean onTouchEvent(MotionEvent e) {
    switch (e.getAction()) {
        case MotionEvent.ACTION_DOWN:
            mDragPosition = getChildAdapterPosition(findChildViewUnder(e.getX(), e.getY()));
            if (mDragPosition != RecyclerView.NO_POSITION) {
                mDraggedViewHolder = getChildViewHolder(findChildViewUnder(e.getX(), e.getY()));
                mDragStartX = mDraggedViewHolder.itemView.getX();
                mDragStartY = mDraggedViewHolder.itemView.getY();
                mDragStartTouchX = e.getX();
                mDragStartTouchY = e.getY();
                if (mItemTouchHelper != null) {
                    mItemTouchHelper.startDrag(mDraggedViewHolder);
                }
            }
            return super.onTouchEvent(e);
        case MotionEvent.ACTION_MOVE:
            return mDraggedViewHolder != null && mItemTouchHelper != null && mItemTouchHelper.onTouchEvent(e);
        case MotionEvent.ACTION_UP:
        case MotionEvent.ACTION_CANCEL:
            if (mDraggedViewHolder != null) {
                mDraggedViewHolder.itemView.animate().x(mDragStartX).y(mDragStartY).setDuration(150).start();
                mDraggedViewHolder = null;
                mDragPosition = RecyclerView.NO_POSITION;
                return true;
            }
            return super.onTouchEvent(e);
    }
    return super.onTouchEvent(e);
}