将远程文件直接下载到客户端？ [英] Download remote file straight to client?

问题描述

我需要直接下载到客户端的远程文件。经过一些搜索，我发现这个脚本在php手册，但其恢复能力不起作用。该脚本使用 Http_Range 来生成可恢复的下载链接。还有其他方法吗？当然，通过使用 cUrl ，但是我需要直接下载到客户端的远程文件。我如何解决这个问题？

I need download remote file straight to client. After some googling, I found this script in the php manual but its resume capability does not work. This script uses Http_Range to generate a resumable download link. Is there any other method to do this? Of course, it would be by using cUrl but I need download remote file straight to client. How can i resolve this problem?

<?php          
$url="http://dl.remote-domain.com/files/file.mp4";
dl_file_resumable($url);

function dl_file_resumable($file, $is_resume=TRUE)
{


    //Gather relevent info about file
    $size = remotefilesize($file);
    $fileinfo = pathinfo($file);

    //workaround for IE filename bug with multiple periods / multiple dots in filename
    //that adds square brackets to filename - eg. setup.abc.exe becomes setup[1].abc.exe
    $filename = (strstr($_SERVER['HTTP_USER_AGENT'], 'MSIE')) ?
                  preg_replace('/\./', '%2e', $fileinfo['basename'], substr_count($fileinfo

['basename'], '.') - 1) :
                  $fileinfo['basename'];

    $file_extension = strtolower($path_info['extension']);

    //This will set the Content-Type to the appropriate setting for the file
    switch($file_extension)
    {
        case 'exe': $ctype='application/octet-stream'; break;
        case 'zip': $ctype='application/zip'; break;
        case 'mp3': $ctype='audio/mpeg'; break;
        case 'mpg': $ctype='video/mpeg'; break;
        case 'avi': $ctype='video/x-msvideo'; break;
        default:    $ctype='application/force-download';
    }

    //check if http_range is sent by browser (or download manager)
    if($is_resume && isset($_SERVER['HTTP_RANGE']))
    {
        list($size_unit, $range_orig) = explode('=', $_SERVER['HTTP_RANGE'], 2);

        if ($size_unit == 'bytes')
        {
            //multiple ranges could be specified at the same time, but for simplicity only 

serve the first range
            //http://tools.ietf.org/id/draft-ietf-http-range-retrieval-00.txt
            list($range, $extra_ranges) = explode(',', $range_orig, 2);
        }
        else
        {
            $range = '';
        }
    }
    else
    {
        $range = '';
    }

    //figure out download piece from range (if set)
    list($seek_start, $seek_end) = explode('-', $range, 2);

    //set start and end based on range (if set), else set defaults
    //also check for invalid ranges.
    $seek_end = (empty($seek_end)) ? ($size - 1) : min(abs(intval($seek_end)),($size - 1));
    $seek_start = (empty($seek_start) || $seek_end < abs(intval($seek_start))) ? 0 : max(abs

(intval($seek_start)),0);

    //add headers if resumable
    if ($is_resume)
    {
        //Only send partial content header if downloading a piece of the file (IE workaround)
        if ($seek_start > 0 || $seek_end < ($size - 1))
        {
            header('HTTP/1.1 206 Partial Content');
        }

        header('Accept-Ranges: bytes');
        header('Content-Range: bytes '.$seek_start.'-'.$seek_end.'/'.$size);
    }

    //headers for IE Bugs (is this necessary?)
    //header("Cache-Control: cache, must-revalidate");   
    //header("Pragma: public");

    header('Content-Type: ' . $ctype);
    header('Content-Disposition: attachment; filename="' . $filename . '"');
    header('Content-Length: '.($seek_end - $seek_start + 1));

    //open the file
    $fp = fopen($file, 'rb');
    //seek to start of missing part
    fseek($fp, $seek_start);

    //start buffered download
    while(!feof($fp))
    {
        //reset time limit for big files
        set_time_limit(0);
        print(fread($fp, 1024*8));
        flush();
        ob_flush();
    }

    fclose($fp);
    exit;
}

function remotefilesize($url, $user = "", $pw = "")
{
    ob_start();
    $ch = curl_init($url);
    curl_setopt($ch, CURLOPT_HEADER, 1);
    curl_setopt($ch, CURLOPT_NOBODY, 1);

    if(!empty($user) && !empty($pw))
    {
        $headers = array('Authorization: Basic ' .  base64_encode("$user:$pw"));
        curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
    }

    $ok = curl_exec($ch);
    curl_close($ch);
    $head = ob_get_contents();
    ob_end_clean();

    $regex = '/Content-Length:\s([0-9].+?)\s/';
    $count = preg_match($regex, $head, $matches);

    return isset($matches[1]) ? $matches[1] : "unknown";
}
?>

推荐答案

如果您只想将文件推送给用户，请按照这些步骤：

If you want to just push file to user, follow these steps:

1. 启动输出缓冲。


2. 按原样读取文件内容到缓冲区。


3. 设置响应头是在mime类型（如您发布的代码中）。


4. 刷新输出缓冲区。

1. Start output buffering.
2. Read the file content as-is to buffer.
3. Set response header beased on mime type (as in the code you posted.)
4. Flush the output buffer.

如果mime类型根据浏览器标准不可渲染，用户将被提示保存文件。

User will be prompted to save the file, if the mime type is not renderable as per browser standards.

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