phpexcel中PHPExcel_Exception Invalid cell coordinate [1解决办法

1、当导出的首行字段超过26的字符的时候，就会报出错误，错误信息如下：
PHPExcel_Exception Invalid cell coordinate [1
原因：
这个不是条数多了出问题，而是列超过26列出的问题。
仔细看看excel表格，z后面是AA、AB、AC，因此输出的时候需要判断。
解决办法：

public function actionExcel(){    /** Include PHPExcel */    require_once dirname(dirname(__FILE__)) . '/components/PHPExcel.php';    $objPHPExcel = new PHPExcel();    $excel_data = self::getExcelData();    $objPHPExcel->getProperties()->setCreator("suv3")        ->setLastModifiedBy("suv3")        ->setTitle("suv3")        ->setSubject("suv3")        ->setDescription("suv3")        ->setKeywords("suv3")        ->setCategory("suv3");    //表头    $first_row_name = ['日期', '渠道', '新增账号', 'D1累计', 'D1LTV', 'D2累计', 'D2LTV', 'D3累计', 'D3LTV', 'D4累计', 'D4LTV', 'D5累计', 'D5LTV', 'D6累计', 'D6LTV', 'D7累计', 'D7LTV',        'D15累计', 'D15LTV', 'D30累计', 'D30LTV', 'D45累计', 'D45LTV', 'D60累计', 'D60LTV', 'D75累计', 'D75LTV', 'D90累计', 'D90LTV'];    $ordA = ord('A'); //65    $key2 = ord("@"); //64    $objPHPExcel->setActiveSheetIndex(0); //表示使用的是第一个sheet    foreach ($first_row_name as $key => $val)    {        if($ordA > ord("Z"))        {            $colum = chr(ord("A")).chr(++$key2);//超过26个字母 AA1,AB1,AC1,AD1...BA1,BB1...        }        else        {            $colum = chr($ordA++);        }        $objPHPExcel->getActiveSheet()->SetCellValue($colum.'1', $val);    }    $index_row = 2; //从第二行开始插入数据    $ii = 0;    foreach ($excel_data as $kk => $rows)    {        $ordA = ord('A');//重新从A开始        $key2 = ord("@"); //64        foreach($rows as $key => $val)        {            if($ordA > ord("Z"))            {                $colum = chr(ord("A")).chr(++$key2);//超过26个字母 AA1,AB1,AC1,AD1...BA1,BB1...            }            else            {                $colum = chr($ordA++);            }            $objPHPExcel->getActiveSheet()->setCellValue($colum.$index_row, $val);        }        $index_row++;    }    $pro_name = Product::find()->select(['product_name'])->andWhere(['product_id' => \Yii::$app->request->get('pro_id')])->asArray()->one()['product_name'];    $excel_name = $pro_name . '-付费分析';    header('Content-Type: application/vnd.openxmlformats-officedocument.spreadsheetml.sheet');    header('Content-Disposition: attachment;filename="' . $excel_name . '.xlsx"');    header('Cache-Control: max-age=0');    header('Cache-Control: max-age=1');// If you're serving to IE 9, then the following may be needed    header ('Expires: Mon, 26 Jul 1997 05:00:00 GMT'); // Date in the past    header ('Last-Modified: '.gmdate('D, d M Y H:i:s').' GMT'); // always modified    header ('Cache-Control: cache, must-revalidate'); // HTTP/1.1    header ('Pragma: public'); // HTTP/1.0    $objWriter = PHPExcel_IOFactory::createWriter($objPHPExcel, 'Excel2007');    $objWriter->save('php://output');//文件通过浏览器下载    exit;}