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();      }    });