php - curl 获取远程文件并同时强制下载

Question

我正在尝试获取远程文件并同时强制将其下载给用户。我无法粘贴代码，代码太长了。但是 curl 函数有效，但问题是它在首先获取远程文件然后强制将其下载给用户之前不会输出任何内容。

我用它来告诉 curl 返回回调

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

现在在我的 readCallback 函数中我这样做了:

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

但它不会返回任何内容，它只是等待获取远程文件完成。

Answer 1

试试这个，它将使用 curl 获取文件的总大小，然后下载文件的部分块代理它给用户，因为没有 wait curl 首先下载它，我用 avi、mp4、mp3 和 exe 对此进行了测试，希望对您有所帮助:

<?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);
}
?>