通过php下载文件并重命名

$filename = dirname(__FILE__) . '/oldfilename.jpg';
$out_filename = 'newfilename.jpg';
if( ! file_exists($filename)){
　　echo 'Not Found' . $filename;
　　exit;
} else {
　　// We'll be outputting a file
　　header('Accept-Ranges: bytes');
　　header('Accept-Length: ' . filesize($filename));
　　// It will be called
　　header('Content-Transfer-Encoding: binary');
　　header('Content-type: application/octet-stream');
　　header('Content-Disposition: attachment; filename=' . $out_filename);
　　header('Content-Type: application/octet-stream; name=' . $out_filename);
　　// The source is in filename
   if(is_file($filename) && is_readable($filename)){
　　　　$file = fopen($filename, "r");
　　　　echo fread($file, filesize($filename));
　　　　fclose($file);
   }
　　exit;
}