Android仿QQ列表左滑删除操作

public class LeftSwipeMenuRecyclerView extends RecyclerView {

  //置顶按钮
  private TextView tvTop;
  //删除按钮
  private TextView tvDelete;
  //item相应的布局
  private LinearLayout mItemLayout;
  //菜单的最大宽度
  private int mMaxLength;

  //上一次触摸行为的x坐标
  private int mLastX;
  //上一次触摸行为的y坐标
  private int mLastY;

  //当前触摸的item的位置
  private int mPosition;

  //是否在垂直滑动列表
  private boolean isDragging;
  //item是在否跟随手指移动
  private boolean isItemMoving;
  //item是否开始自动滑动
  private boolean isStartScroll;

  //左滑菜单状态  0：关闭 1：将要关闭 2：将要打开 3：打开
  private int mMenuState;
  private static int MENU_CLOSED = 0;
  private static int MENU_WILL_CLOSED = 1;
  private static int MENU_OPEN = 2;
  private static int MENU_WILL_OPEN = 3;

  //实现弹性滑动，恢复
  private Scroller mScroller;

  //item的事件监听
  private OnItemActionListener mListener;

  public LeftSwipeMenuRecyclerView(Context context) {
    this(context, null);
  }

  public LeftSwipeMenuRecyclerView(Context context, @Nullable AttributeSet attrs) {
    this(context, attrs, 0);
  }

  public LeftSwipeMenuRecyclerView(Context context, @Nullable AttributeSet attrs, int defStyle) {
    super(context, attrs, defStyle);
    mScroller = new Scroller(context, new LinearInterpolator());
  }

int x= (int) event.getX();
int y= (int) event.getY();

case MotionEvent.ACTION_DOWN:
        if (mMenuState == MENU_CLOSED) {
          //根据坐标获得view
          View view = findChildViewUnder(x, y);
          if (view == null) {
            return false;
          }
          //获得这个view的ViewHolder
          RVAdapter.Holder holder = (RVAdapter.Holder) getChildViewHolder(view);
          //获得这个view的position
          mPosition = holder.getAdapterPosition();
          //获得这个view的整个布局
          mItemLayout = holder.llLayout;
          //获得这个view的删除按钮
          tvDelete = holder.tvDelete;
          //这个view的整个置顶按钮
          tvTop = holder.tvTop;
          //两个按钮的宽度
          mMaxLength = tvDelete.getWidth() + tvTop.getWidth();

          //设置删除按钮点击监听
          tvDelete.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View view) {
              mItemLayout.scrollTo(0, 0);
              mMenuState =MENU_CLOSED;
              mListener.OnItemDelete(mPosition);
            }
          });
          //设置置顶按钮点击监听
          tvTop.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View view) {
              mItemLayout.scrollTo(0, 0);
              mMenuState =MENU_CLOSED;
              mListener.OnItemTop(mPosition);
            }
          });
          //如果是打开状态，点击其他就把当前menu关闭掉
        } else if (mMenuState == MENU_OPEN) {
          mScroller.startScroll(mItemLayout.getScrollX(), 0, -mMaxLength, 0, 200);
          invalidate();
          mMenuState = MENU_CLOSED;
          //该点击无效
          return false;
        } else {
          return false;
        }
        break;

      case MotionEvent.ACTION_MOVE:
        //计算偏移量
        int dx = mLastX - x;
        int dy = mLastY - y;
        //当前滑动的x
        int scrollx = mItemLayout.getScrollX();

        if (Math.abs(dx) > Math.abs(dy)) {

          isItemMoving = true;
          //超出左边界则始终保持不动
          if (scrollx + dx <= 0) {
            mItemLayout.scrollTo(0, 0);
            //滑动无效
            return false;
          //超出右边界则始终保持不动
          } else if (scrollx + dx >= mMaxLength) {
            mItemLayout.scrollTo(mMaxLength, 0);
            //滑动无效
            return false;
          }
          //菜单随着手指移动
          mItemLayout.scrollBy(dx, 0);
        //如果水平移动距离大于30像素的话，recyclerView不会上下滑动
        }else if (Math.abs(dx) > 30){
          return true;
        }
        //如果菜单正在打开就不能上下滑动
        if (isItemMoving){
          mLastX = x;
          mLastY = y;
          return true;
        }
        break;

case MotionEvent.ACTION_UP:
        //手指抬起时判断是否点击,静止且有Listener才能点击
        if (!isItemMoving && !isDragging && mListener != null) {
          mListener.OnItemClick(mPosition);
        }
        isItemMoving = false;

        //等一下要移动的距离
        int deltaX = 0;
        int upScrollx = mItemLayout.getScrollX();
        //滑动距离大于1/2menu长度就自动展开，否则就关掉
        if (upScrollx >= mMaxLength / 2) {
          deltaX = mMaxLength - upScrollx;
          mMenuState = MENU_WILL_OPEN;
        } else if (upScrollx < mMaxLength / 2) {
          deltaX = -upScrollx;
          mMenuState = MENU_WILL_CLOSED;
        }
        //知道我们为什么不直接把mMenuState赋值为MENU_OPEN或者MENU_CLOSED吗？因为滑动时有时间的，我们可以在滑动完成时才把状态改为已经完成
        mScroller.startScroll(upScrollx, 0, deltaX, 0, 200);
        isStartScroll = true;
        //刷新界面
        invalidate();
        break;

   //只有更新mLastX，mLastY数据才会准确
    mLastX = x;
    mLastY = y;
    return super.onTouchEvent(e);

  public void computeScroll() {
    //判断scroller是否完成滑动
    if (mScroller.computeScrollOffset()) {
      mItemLayout.scrollTo(mScroller.getCurrX(), mScroller.getCurrY());
      //这个很重要
      invalidate();
    //如果已经完成就改变状态
    } else if (isStartScroll) {
      isStartScroll = false;
      if (mMenuState == MENU_WILL_CLOSED) {
        mMenuState = MENU_CLOSED;
      }
      if (mMenuState == MENU_WILL_OPEN) {
        mMenuState = MENU_OPEN;
      }
    }
  }

 @Override
  public void onScrollStateChanged(int state) {
    super.onScrollStateChanged(state);
    //是否在上下滑动
    isDragging = state == SCROLL_STATE_DRAGGING;
  }

//设置Listener
  public void setOnItemActionListener(OnItemActionListener onItemActionListener) {
    this.mListener = onItemActionListener;
  }

public interface OnItemActionListener {
  void OnItemClick(int position);
  void OnItemTop(int position);
  void OnItemDelete(int position);
}

rv.setOnItemActionListener(new OnItemActionListener() {
      //点击
      @Override
      public void OnItemClick(int position) {
        Toast.makeText(MainActivity.this,"Click"+position,Toast.LENGTH_SHORT).show();
      }
      //置顶
      @Override
      public void OnItemTop(int position) {
        //获得当前位置的内容
        String temp =list.get(position);
        //移除这个item
        list.remove(position);
        //把它添加到第一个
        list.addFirst(temp);
        //更新数据源
        adapter.notifyDataSetChanged();
      }
      //删除
      @Override
      public void OnItemDelete(int position) {
        list.remove(position);
        //更新数据源
        adapter.notifyDataSetChanged();
      }
    });