public class LeftSwipeMenuRecyclerView extends RecyclerView {  //置頂按鈕  private TextView tvTop;  //刪除按鈕  private TextView tvDelete;  //item相應的布局  private LinearLayout mItemLayout;  //菜單的最大寬度  private int mMaxLength;  //上一次觸摸行為的x坐標  private int mLastX;  //上一次觸摸行為的y坐標  private int mLastY;  //當前觸摸的item的位置  private int mPosition;  //是否在垂直滑動列表  private boolean isDragging;  //item是在否跟隨手指移動  private boolean isItemMoving;  //item是否開始自動滑動  private boolean isStartScroll;  //左滑菜單狀態  0：關閉 1：將要關閉 2：將要打開 3：打開  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;  //實現彈性滑動，恢復  private Scroller mScroller;  //item的事件監聽  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) {          //根據坐標獲得view          View view = findChildViewUnder(x, y);          if (view == null) {            return false;          }          //獲得這個view的ViewHolder          RVAdapter.Holder holder = (RVAdapter.Holder) getChildViewHolder(view);          //獲得這個view的position          mPosition = holder.getAdapterPosition();          //獲得這個view的整個布局          mItemLayout = holder.llLayout;          //獲得這個view的刪除按鈕          tvDelete = holder.tvDelete;          //這個view的整個置頂按鈕          tvTop = holder.tvTop;          //兩個按鈕的寬度          mMaxLength = tvDelete.getWidth() + tvTop.getWidth();          //設置刪除按鈕點擊監聽          tvDelete.setOnClickListener(new OnClickListener() {            @Override            public void onClick(View view) {              mItemLayout.scrollTo(0, 0);              mMenuState =MENU_CLOSED;              mListener.OnItemDelete(mPosition);            }          });          //設置置頂按鈕點擊監聽          tvTop.setOnClickListener(new OnClickListener() {            @Override            public void onClick(View view) {              mItemLayout.scrollTo(0, 0);              mMenuState =MENU_CLOSED;              mListener.OnItemTop(mPosition);            }          });          //如果是打開狀態，點擊其他就把當前menu關閉掉        } else if (mMenuState == MENU_OPEN) {          mScroller.startScroll(mItemLayout.getScrollX(), 0, -mMaxLength, 0, 200);          invalidate();          mMenuState = MENU_CLOSED;          //該點擊無效          return false;        } else {          return false;        }        break;

      case MotionEvent.ACTION_MOVE:        //計算偏移量        int dx = mLastX - x;        int dy = mLastY - y;        //當前滑動的x        int scrollx = mItemLayout.getScrollX();        if (Math.abs(dx) > Math.abs(dy)) {          isItemMoving = true;          //超出左邊界則始終保持不動          if (scrollx + dx <= 0) {            mItemLayout.scrollTo(0, 0);            //滑動無效            return false;          //超出右邊界則始終保持不動          } else if (scrollx + dx >= mMaxLength) {            mItemLayout.scrollTo(mMaxLength, 0);            //滑動無效            return false;          }          //菜單隨著手指移動          mItemLayout.scrollBy(dx, 0);        //如果水平移動距離大于30像素的話，recyclerView不會上下滑動        }else if (Math.abs(dx) > 30){          return true;        }        //如果菜單正在打開就不能上下滑動        if (isItemMoving){          mLastX = x;          mLastY = y;          return true;        }        break;

case MotionEvent.ACTION_UP:        //手指抬起時判斷是否點擊,靜止且有Listener才能點擊        if (!isItemMoving && !isDragging && mListener != null) {          mListener.OnItemClick(mPosition);        }        isItemMoving = false;        //等一下要移動的距離        int deltaX = 0;        int upScrollx = mItemLayout.getScrollX();        //滑動距離大于1/2menu長度就自動展開，否則就關掉        if (upScrollx >= mMaxLength / 2) {          deltaX = mMaxLength - upScrollx;          mMenuState = MENU_WILL_OPEN;        } else if (upScrollx < mMaxLength / 2) {          deltaX = -upScrollx;          mMenuState = MENU_WILL_CLOSED;        }        //知道我們為什么不直接把mMenuState賦值為MENU_OPEN或者MENU_CLOSED嗎？因為滑動時有時間的，我們可以在滑動完成時才把狀態改為已經完成        mScroller.startScroll(upScrollx, 0, deltaX, 0, 200);        isStartScroll = true;        //刷新界面        invalidate();        break;

   //只有更新mLastX，mLastY數據才會準確    mLastX = x;    mLastY = y;    return super.onTouchEvent(e);

  public void computeScroll() {    //判斷scroller是否完成滑動    if (mScroller.computeScrollOffset()) {      mItemLayout.scrollTo(mScroller.getCurrX(), mScroller.getCurrY());      //這個很重要      invalidate();    //如果已經完成就改變狀態    } 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);    //是否在上下滑動    isDragging = state == SCROLL_STATE_DRAGGING;  }

//設置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() {      //點擊      @Override      public void OnItemClick(int position) {        Toast.makeText(MainActivity.this,"Click"+position,Toast.LENGTH_SHORT).show();      }      //置頂      @Override      public void OnItemTop(int position) {        //獲得當前位置的內容        String temp =list.get(position);        //移除這個item        list.remove(position);        //把它添加到第一個        list.addFirst(temp);        //更新數據源        adapter.notifyDataSetChanged();      }      //刪除      @Override      public void OnItemDelete(int position) {        list.remove(position);        //更新數據源        adapter.notifyDataSetChanged();      }    });