phpexcel5 问题 undefined $xfindex

if (isset($this->_mapCellXfIndex[$xfIndex])) {
                $this->_phpSheet->getColumnDimensionByColumn($i)->setXfIndex($this->_mapCellXfIndex[$xfIndex]);
            } else {
                $this->_phpSheet->getColumnDimensionByColumn($i)->setXfIndex(current($this->_mapCellXfIndex));
            }