PHP下载文件

// 方法一
$file='alonesky/index.php';
echo download($file);
function download($file){
    if(empty($file)||!is_file($file)||!file_exists($file)){
        echo '404';
        exit;
    }
    header('Content-Type:application/octet-stream');
    $fileName=basename($file);
    header('Content-Disposition:attachment;filename="'.$fileName.'"');
    $buffer='';
    $cnt=0;
    $handle=fopen($file,'rb');
    if($handle===false){
        return false;
    }
    while(!feof($handle)){
        $buffer=fread($handle,1024*1024);
        echo $buffer;
        ob_flush();
        flush();
        $cnt+=strlen($buffer);
    }
    $status=fclose($handle);
    if($status){
        return $cnt;
    }
    return $status;
}
// 方法二
$filename="alonesky/index.php";
header("Content-Type: application/force-download");
header("Content-Disposition: attachment; filename=".$filename);
readfile($filename);exit;