php xls如何转csv

<?php 
 header("Content-Type:text/html;charset=utf-8");
 require_once 'PHPExcel/PHPExcel.php'; 
 $d = dir('xls/');
 while (($file = $d->read()) !== false){
 if(substr(strrchr($file, '.'), 1) == 'xls'){
 $arr[] = $file; 
 }
 }
 //把所有xls文件列出列表，勾选提交到这边$_POST
 foreach($_POST as $k => $item){
 foreach($item as $v){
 //只获取文件名
 $file = str_replace('.xls','',$arr[$v]);
 getCsv($file);
 }
 }
 function getCsv($file){
 $filename = "xls/".$file.".xls";
 $objReader = new PHPExcel_Reader_Excel5();
 //$objReader = PHPExcel_IOFactory::createReader('Excel5');
 $objPHPExcel = $objReader->load($filename);
 //$objWriter = PHPExcel_IOFactory::createWriter($objPHPExcel, 'CSV');
 $objWriter = new PHPExcel_Writer_CSV($objPHPExcel);
 $objWriter->save(str_replace('.xls', '.csv',$filename));
 $root = "xls/".$file.".csv";
 $newRoot='csv/'.$file.'.csv'; //新目录
 copy($root,$newRoot); //拷贝到新目录
 unlink($root); //删除旧目录下的文件
 } 
?>