private List<SHMessage> mSelectList = new ArrayList<>();
    private Map<String,Boolean> mSelectMap = new HashMap<>();
    private int multiSelectVisibility = View.GONE;

    public void setMultiSelect(boolean open){
        multiSelectVisibility = open ?  View.VISIBLE : View.GONE;
        if(open){
            mSelectList.clear();
            mSelectMap.clear();
        }

    }

    private void setCheckBox(BaseViewHolder helper, SHMessage item){
        CheckBox checkBox = helper.getView(R.id.cb_chat);
        if(checkBox == null){
            return;
        }

        ConstraintLayout constraintLayout = helper.getView(R.id.cl_item_chat);
        ConstraintSet constraintSet = new ConstraintSet();
        constraintSet.clone(constraintLayout);
        constraintSet.setVisibility(R.id.cb_chat,  multiSelectVisibility);
        constraintSet.applyTo(constraintLayout);

        // 由于复用，必须先解除OnCheckedChangeListener，再设置选中状态
        checkBox.setOnCheckedChangeListener(null);
        Boolean isCheck = mSelectMap.get(item.getLogId());
        if(isCheck == null){
            isCheck = false;
        }
        checkBox.setChecked(isCheck);

        checkBox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
            @Override
            public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
               // 此处不要 以 position作为key，下拉加载更多时，position会变动
                mSelectMap.put(item.getLogId(), isChecked);
                /* 将 CheckBox 选中的 item 按选择顺序添加到 List 里 */
                if (isChecked) {
                   mSelectList.add(item);
                } else {
                   mSelectList.remove(item);

                }
            }
        });

    }