curl获取远程文件和强制下载同时

问题描述

我试图获取一个远程文件，并强制将其下载到用户的同时。
我无法粘贴代码，代码太长。但curl函数工作，但问题是它不会放任何东西，直到它获得远程文件，然后它强制下载它到用户。

I'm trying to get a remote file and force download it to user at the same time.I can't paste the code ,the code is too long . but the curl function works ,but the problem is it doesn't out put anything till it gets the remote file first then it force downloads it to user.

我使用这个告诉curl返回回调

I use this to tell curl to return a callback

curl_setopt($ch, CURLOPT_READFUNCTION, 'readCallback');

现在在我的readCallback函数中我这样做：

now in my readCallback function I do this :

function readCallback($curl, $stream, $maxRead){
    $read = fgets($stream, $maxRead);
    echo $read;
    return $read;
}

但它不返回任何只是等待直到抓取远程文件完成。

but it doesn't return anything it just waits till fetching remote file is finished.

推荐答案

尝试这样，它将使用curl获取文件的总大小，然后下载文件的部分块给用户，因为没有等待 curl下载它，我测试这与avi，mp4，mp3和一个exe，希望它有帮助：

Try this, it will use curl to get the total size of the file then download partial chunks of the file proxying it to the user so as there is no wait for curl to download it first, I tested this with an avi,mp4,mp3 and an exe, hope it helps:

<?php
$file = 'http://example.com/somefile.mp3';
download($file,2000);

/*
Set Headers
Get total size of file
Then loop through the total size incrementing a chunck size
*/
function download($file,$chunks){
    set_time_limit(0);
    header('Content-Description: File Transfer');
    header('Content-Type: application/octet-stream');
    header('Content-disposition: attachment; filename='.basename($file));
    header('Cache-Control: must-revalidate, post-check=0, pre-check=0');
    header('Expires: 0');
    header('Pragma: public');
    $size = get_size($file);
    header('Content-Length: '.$size);

    $i = 0;
    while($i<=$size){
        //Output the chunk
        get_chunk($file,(($i==0)?$i:$i+1),((($i+$chunks)>$size)?$size:$i+$chunks));
        $i = ($i+$chunks);
    }

}

//Callback function for CURLOPT_WRITEFUNCTION, This is what prints the chunk
function chunk($ch, $str) {
    print($str);
    return strlen($str);
}

//Function to get a range of bytes from the remote file
function get_chunk($file,$start,$end){
    $ch = curl_init();
    curl_setopt($ch, CURLOPT_URL, $file);
    curl_setopt($ch, CURLOPT_RANGE, $start.'-'.$end);
    curl_setopt($ch, CURLOPT_BINARYTRANSFER, 1);
    curl_setopt($ch, CURLOPT_WRITEFUNCTION, 'chunk');
    $result = curl_exec($ch);
    curl_close($ch);
}

//Get total size of file
function get_size($url){
    $ch = curl_init();
    curl_setopt($ch, CURLOPT_URL, $url);
    curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($ch, CURLOPT_HEADER, true);
    curl_setopt($ch, CURLOPT_NOBODY, true);
    curl_exec($ch);
    $size = curl_getinfo($ch, CURLINFO_CONTENT_LENGTH_DOWNLOAD);
    return intval($size);
}
?>

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