PHP ヘッダーとファイル処理を使用してファイルのダウンロードを強制する方法

<code class="php">header("Cache-Control: private");
header("Content-Type: application/stream");
header("Content-Length: ".$fileSize);  // File size in bytes
header("Content-Disposition: attachment; filename=".$fileName);  // File name to display</code>

<code class="php">readfile ($filePath);                   
exit();</code>

<code class="php"><?php
    // Fetch the file info.
    $filePath = '/path/to/file/on/disk.jpg';

    if(file_exists($filePath)) {
        $fileName = basename($filePath);
        $fileSize = filesize($filePath);

        // Output headers.
        header("Cache-Control: private");
        header("Content-Type: application/stream");
        header("Content-Length: ".$fileSize);
        header("Content-Disposition: attachment; filename=".$fileName);

        // Output file.
        readfile ($filePath);                   
        exit();
    }
    else {
        die('The provided file path is not valid.');
    }
?></code>

<code class="html"><a href="download.php?file=/path/to/file.jpg">Download</a></code>

<code class="php"><?php
    $file = $_GET['file'];

    if(file_exists($file)) {
        // Display confirmation panel...
        if(isset($_POST['confirm'])) {  // Confirm button clicked
            header("Cache-Control: private");
            header("Content-Type: application/stream");
            header("Content-Length: ".filesize($file));
            header("Content-Disposition: attachment; filename=".basename($file));

            readfile ($file);                   
            exit();
        }
    }
    else {
        die('Invalid file path.');
    }
?></code>