php导出下载Excel文件被IE阻止，如何解决？用流输出也不行

 
 $file_name="test.xls"; 
 $file_path="../data/down/2011/03/21/"; 
 $file_name = urldecode($file_name); 

 // ../ is not allowed in the file name 
 if (!ereg("(\.\.\/)", $file_name)) 
 { 
 // Does the file exist? 
 	if (file_exists($file_path . $file_name)) 
 	{ 
 		$fp = @fopen( $file_path . $file_name, "r" ); 
 		//Prompt the user to download the new torrent file. 
 		header("Expires: 0" ); 
 		header("Pragma:public" ); 
 		header("Cache-Control:must-revalidate,post-check=0,pre-check=0" ); 
 		header("Cache-Control:public"); 
 		header("Content-Type:application/octet-stream" ); 

 		if (strstr($_SERVER["HTTP_USER_AGENT"],"MSIE"))	{ 
 			header("Content-Disposition:attachment;filename=".urlencode($file_name) ); 
 		}else{ 
 			header("Content-Disposition:attachment;filename=".$file_name ); 
 		} 
 		header("Content-transfer-encoding: binary"); 
 		header("Content-length:".@filesize( $file_path . $file_name )); 

 		@fpassthru( $fp ); 
 		@fclose( $fp ); 
  	} 
 	exit(); 
 }