如何使用 PHP 强制文件下载

Question

我想要求在用户使用 PHP 访问网页时下载文件。我认为它与file_get_contents有关，但不确定如何执行。

$url = "http://example.com/go.exe";

使用header(location) 下载文件后，它不会重定向到另一个页面。它只是停止。

Answer 1

阅读有关内置 PHP 函数 readfile 的文档

$file_url = 'http://www.myremoteserver.com/file.exe';
header('Content-Type: application/octet-stream');
header("Content-Transfer-Encoding: Binary"); 
header("Content-disposition: attachment; filename=\"" . basename($file_url) . "\""); 
readfile($file_url); 

还要确保根据您的文件 application/zip、application/pdf 等添加正确的内容类型 - 但前提是您不想触发另存为对话框。

Answer 2

<?php
$file = "http://example.com/go.exe"; 

header("Content-Description: File Transfer"); 
header("Content-Type: application/octet-stream"); 
header("Content-Disposition: attachment; filename=\"". basename($file) ."\""); 

readfile ($file);
exit(); 
?>

或者，当文件无法用浏览器打开时，您可以使用Location 标头：

<?php header("Location: http://example.com/go.exe"); ?>

Answer 3

header("Content-Type: application/octet-stream");
header("Content-Transfer-Encoding: Binary");
header("Content-disposition: attachment; filename=\"file.exe\""); 
echo readfile($url);

是正确的

对于 exe 类型的文件，或者更好的一个

header("Location: $url");

Answer 4

试试这个：

header('Content-type: audio/mp3'); 
header('Content-disposition: attachment; 
filename=“'.$trackname'”');                             
readfile('folder name /'.$trackname);          
exit();

Answer 5

http://php.net/manual/en/function.readfile.php

这就是你所需要的。 “Monkey.gif”改成你的文件名。如果需要从其他服务器下载，“monkey.gif”改为“http://www.exsample.com/go.exe”

Answer 6

对上面接受的答案的修改，它还在运行时检测 MIME 类型：

$finfo = finfo_open(FILEINFO_MIME_TYPE);
header('Content-Type: '.finfo_file($finfo, $path));

$finfo = finfo_open(FILEINFO_MIME_ENCODING);
header('Content-Transfer-Encoding: '.finfo_file($finfo, $path)); 

header('Content-disposition: attachment; filename="'.basename($path).'"'); 
readfile($path); // do the double-download-dance (dirty but worky)

Answer 7

首先显示您的文件并将其值设置为 url。

index.php

<a href="download.php?download='.$row['file'].'" title="Download File">

下载.php

<?php
/*db connectors*/
include('dbconfig.php');

/*function to set your files*/
function output_file($file, $name, $mime_type='')
{
    if(!is_readable($file)) die('File not found or inaccessible!');
    $size = filesize($file);
    $name = rawurldecode($name);
    $known_mime_types=array(
        "htm" => "text/html",
        "exe" => "application/octet-stream",
        "zip" => "application/zip",
        "doc" => "application/msword",
        "jpg" => "image/jpg",
        "php" => "text/plain",
        "xls" => "application/vnd.ms-excel",
        "ppt" => "application/vnd.ms-powerpoint",
        "gif" => "image/gif",
        "pdf" => "application/pdf",
        "txt" => "text/plain",
        "html"=> "text/html",
        "png" => "image/png",
        "jpeg"=> "image/jpg"
    );

    if($mime_type==''){
        $file_extension = strtolower(substr(strrchr($file,"."),1));
        if(array_key_exists($file_extension, $known_mime_types)){
            $mime_type=$known_mime_types[$file_extension];
        } else {
            $mime_type="application/force-download";
        };
    };
    @ob_end_clean();
    if(ini_get('zlib.output_compression'))
    ini_set('zlib.output_compression', 'Off');
    header('Content-Type: ' . $mime_type);
    header('Content-Disposition: attachment; filename="'.$name.'"');
    header("Content-Transfer-Encoding: binary");
    header('Accept-Ranges: bytes');

    if(isset($_SERVER['HTTP_RANGE']))
    {
        list($a, $range) = explode("=",$_SERVER['HTTP_RANGE'],2);
        list($range) = explode(",",$range,2);
        list($range, $range_end) = explode("-", $range);
        $range=intval($range);
        if(!$range_end) {
            $range_end=$size-1;
        } else {
            $range_end=intval($range_end);
        }

        $new_length = $range_end-$range+1;
        header("HTTP/1.1 206 Partial Content");
        header("Content-Length: $new_length");
        header("Content-Range: bytes $range-$range_end/$size");
    } else {
        $new_length=$size;
        header("Content-Length: ".$size);
    }

    $chunksize = 1*(1024*1024);
    $bytes_send = 0;
    if ($file = fopen($file, 'r'))
    {
        if(isset($_SERVER['HTTP_RANGE']))
        fseek($file, $range);

        while(!feof($file) &&
            (!connection_aborted()) &&
            ($bytes_send<$new_length)
        )
        {
            $buffer = fread($file, $chunksize);
            echo($buffer);
            flush();
            $bytes_send += strlen($buffer);
        }
        fclose($file);
    } else
        die('Error - can not open file.');
    die();
}
set_time_limit(0);

/*set your folder*/
$file_path='uploads/'."your file";

/*output must be folder/yourfile*/

output_file($file_path, ''."your file".'', $row['type']);

/*back to index.php while downloading*/
header('Location:index.php');
?>

Answer 8

如果您必须下载大小超过允许的内存限制（memory_limit ini 设置）的文件，这会导致 PHP Fatal error: Allowed memory size of 5242880 bytes exhausted 错误，您可以这样做：

// File to download.
$file = '/path/to/file';

// Maximum size of chunks (in bytes).
$maxRead = 1 * 1024 * 1024; // 1MB

// Give a nice name to your download.
$fileName = 'download_file.txt';

// Open a file in read mode.
$fh = fopen($file, 'r');

// These headers will force download on browser,
// and set the custom file name for the download, respectively.
header('Content-Type: application/octet-stream');
header('Content-Disposition: attachment; filename="' . $fileName . '"');

// Run this until we have read the whole file.
// feof (eof means "end of file") returns `true` when the handler
// has reached the end of file.
while (!feof($fh)) {
    // Read and output the next chunk.
    echo fread($fh, $maxRead);

    // Flush the output buffer to free memory.
    ob_flush();
}

// Exit to make sure not to output anything else.
exit;

Answer 9

以下代码是在php中实现下载服务的正确方法，如下tutorial中所述

header('Content-Type: application/zip');
header("Content-Disposition: attachment; filename=\"$file_name\"");
set_time_limit(0);
$file = @fopen($filePath, "rb");
while(!feof($file)) {
    print(@fread($file, 1024*8));
    ob_flush();
    flush();
}

Answer 10

您也可以流式下载，这将大大减少资源消耗。 示例：

$readableStream = fopen('test.zip', 'rb');
$writableStream = fopen('php://output', 'wb');

header('Content-Type: application/octet-stream');
header('Content-Disposition: attachment; filename="test.zip"');
stream_copy_to_stream($readableStream, $writableStream);
ob_flush();
flush();

在上面的示例中，我正在下载一个 test.zip（实际上是我本地机器上的 android studio zip）。 php://output 是只写流（通常由 echo 或 print 使用）。 之后，您只需要设置所需的标头并调用 stream_copy_to_stream(source, destination)。 stream_copy_to_stream() 方法充当管道，从源流（读取流）获取输入并将其通过管道传输到目标流（写入流），它还避免了允许的内存耗尽的问题，所以你实际上可以下载比你的 PHP memory_limit 更大的文件。

Answer 11

我上面的答案有效。但是，我想贡献一个方法来说明如何使用 GET 来执行它

在您的 html/php 页面上

$File = 'some/dir/file.jpg';
<a href="<?php echo '../sumdir/download.php?f='.$File; ?>" target="_blank">Download</a>

和download.php 包含

$file = $_GET['f']; 

header("Expires: 0");
header("Last-Modified: " . gmdate("D, d M Y H:i:s") . " GMT");
header("Cache-Control: no-store, no-cache, must-revalidate");
header("Cache-Control: post-check=0, pre-check=0", false);
header("Pragma: no-cache");

$ext = pathinfo($file, PATHINFO_EXTENSION);
$basename = pathinfo($file, PATHINFO_BASENAME);

header("Content-type: application/".$ext);
header('Content-length: '.filesize($file));
header("Content-Disposition: attachment; filename=\"$basename\"");
ob_clean(); 
flush();
readfile($file);
exit;

这应该适用于任何文件类型。这没有使用 POST 进行测试，但它可以工作。

Answer 12

您可以使用 download 属性来强制下载文件：

<a href="https://test.com/aaa.exe" download>click here to download</a>