PHPSpreadsheet导出Excel列数超过26报错怎么办？

<?php
namespace AppLibrariesExcel;
use PhpOfficePhpSpreadsheetCellDataType;
use PhpOfficePhpSpreadsheetSpreadsheet;
use PhpOfficePhpSpreadsheetWriterXlsx;
class Export
{
    protected $data_type;
    protected $spread_sheet;
    protected $x_lsx;
    public function __construct(DataType$data_type, Spreadsheet$spread_sheet, Xlsx$x_lsx)
    {
        $this->data_type= $data_type;
        $this->spread_sheet= $spread_sheet;
        $this->x_lsx= $x_lsx;
    }
    /**
    * @ description 文件导出
    * @ date 2019-05-06
    * @ array $field_name 字段名称 汉字(索引数组) [&#39;产品&#39;,&#39;姓名&#39;]
    * @ array $data 数据 [&#39;a&#39; => data, &#39;b&#39; => data]
    * @ array $field_column 数据中的下标名称 字段数据 (索引数组) [&#39;a&#39;,&#39;b&#39;]
    * @ string $file_name 文件名称
    * @ array $arr 需要转换为数字的$field_column中的key(索引数组)
    * @ return  file
    */
    public function export($field_name,$data,$field_column,$file_name,$field_numeric_keys= [])
    {
        @ob_clean();
        if (empty($field_name)|| empty($field_column)|| empty($data)|| empty($file_name))return false;
        $sheet= $this->spread_sheet->getActiveSheet();
        //设置header
        $i= 0;
        foreach ($field_name as $value) {
            $cellName= self::stringFromColumnIndex($i). "1";
            $sheet->setCellValue($cellName, $value)->calculateColumnWidths();
            $sheet->getColumnDimension(self::stringFromColumnIndex($i))->setWidth(15);
            $i++;
        }
        //设置value
        $len= count($field_column);
        foreach ($data as $key=> $item) {
            $row= 2 + ($key* 1);
            for ($i= 0; $i< $len; $i++) {
                $sheet->setCellValueExplicit(self::stringFromColumnIndex($i). $row, $item[$field_column[$i]]??"", DataType::TYPE_STRING);
                if (isset($item[$field_column[$i]])&& !empty($field_numeric_keys)&& in_array($field_column[$i],$field_numeric_keys)) {
                $sheet->setCellValueExplicit(self::stringFromColumnIndex($i). $row, $item[$field_column[$i]]??"", DataType::TYPE_NUMERIC);
                }
            }
        }
        $writer= new Xlsx($this->spread_sheet);
        header(&#39;Content-Type: application/vnd.openxmlformats-officedocument.spreadsheetml.sheet&#39;);//告诉浏览器输出07Excel文件
        header(&#39;Content-Disposition: attachment;filename="&#39; . $file_name . &#39;.xlsx"&#39;);//告诉浏览器输出浏览器名称
        header(&#39;Cache-Control: max-age=0&#39;);
        $writer->save(&#39;php://output&#39;);
        @ob_flush();
        @flush();
        exit;
    }
    /**
    * @ description excel导出突破只能26个字段
    * @ date 2019-05-07
    * @ return  string 字段
    */
    public static function stringFromColumnIndex($pColumnIndex = 0)
    {
        static $_indexCache= array();
        if (!isset($_indexCache[$pColumnIndex])) {
            if ($pColumnIndex < 26) {
                $_indexCache[$pColumnIndex]= chr(65 + $pColumnIndex);
            }elseif ($pColumnIndex < 702) {
                $_indexCache[$pColumnIndex]= chr(64 + ($pColumnIndex / 26)). chr(65 + $pColumnIndex % 26);
            }else {
                $_indexCache[$pColumnIndex]= chr(64 + (($pColumnIndex - 26)/ 676)). chr(65 + ((($pColumnIndex - 26)% 676)/ 26)). chr(65 + $pColumnIndex % 26);
            }
        }
        return $_indexCache[$pColumnIndex];
    }
}