PHP下载文件 <a>标签

 1 $filename = "http://www.xxxx.com/images/xiaoxiangmuban.jpg";
 2             $fb = @fopen($filename, "rb+");
 3             if($fb){
 4                 $fileinfo = pathinfo($filename);
 5                 header('Content-type: application/x-'.$fileinfo['extension']);
 6                 header('Content-Transfer-Encoding:binary');  //二进制
 7                 header('Content-Disposition: attachment; filename='.$fileinfo['basename']);
 8                 header('Content-Length: '.filesize($filename));
 9                 ob_clean ();        
10                 flush ();
11                 readfile($filename);
12                 fclose($fb);
13                 exit();
14             }else{
15                 die("文件不存在");
16             }

之前搞了比较久，突然发现代码上部分写了一个header("Content-type:text/html;charset=gbk"),然后后来在大神的执导下用了一个ob_clean()和flush()，然后可以成功下载。