//AAA转换
public static function toAAA($dec)
{
 if ($dec < 0) return '';
 $y = $dec % 26;
 $x = floor($dec / 26);
 return self::toAAA($x - 1) . chr($y + 65);
}

//导出xls
public static function exportXls($array)
{
 set_time_limit(0);
 include(Url::to('@vendor/moonland/phpexcel/PHPExcel.php'));
 include(Url::to('@vendor/moonland/phpexcel/PHPExcel/Writer/Excel2007.php'));
 $titles = $array['titles'];
 $fields = $array['fields'];
 $list = $array['list'];
 $name = $array['name'];
 $count = count($titles);
 $keys = [];//A=>chr(65)
 foreach ($titles as $k => $v) {
 $keys[] = self::toAAA($k);
 }
 $objPHPExcel = new \PHPExcel();
 $objWriter = new \PHPExcel_Writer_Excel2007($objPHPExcel);
 $objPHPExcel->setActiveSheetIndex(0);
 $activeSheet = $objPHPExcel->getActiveSheet();
 $activeSheet->setTitle($name);
 $activeSheet->getStyle("A1:{$keys[$count-1]}1")->getAlignment()->setHorizontal(\PHPExcel_Style_Alignment::HORIZONTAL_CENTER);
 $activeSheet->mergeCells("A1:{$keys[$count-1]}1");
 $activeSheet->setCellValue('A1', $name);
 //设置title,样式
 foreach ($titles as $key => $title) {
 $activeSheet->setCellValue($keys[$key] . '2', $title);
 $activeSheet->getColumnDimension($keys[$key])->setWidth(20);
 $activeSheet->getRowDimension(($key + 1))->setRowHeight(18);
 }
 $i = 3;
 foreach ($list as &$item) {
 foreach ($keys as $k => $v) {
  $val = isset($item[$fields[$k]]) "_" . date('Y_m_d_His') . '.xlsx';
 header("Cache-Control: public");
 header("Pragma: public");
 header("Content-type:application/vnd.ms-excel");
 header("Content-Disposition:attachment;filename=" . iconv("utf-8", "GB2312//TRANSLIT", $fileName));
 header('Content-Type:APPLICATION/OCTET-STREAM');
 ob_clean();
 ob_start();
 $objWriter->save('php://output');
 ob_end_flush();
}
//AAA转换
public static function toAAA($dec)
{
 if ($dec < 0) return '';
 $y = $dec % 26;
 $x = floor($dec / 26);
 return self::toAAA($x - 1) . chr($y + 65);
}