PHP header 下载

1.html

<a href="1.php?filename=xxxx.pdf">下载</a>

1.php

<?php
$filename = $_REQUEST['filename'];
$file = ROOT . $filename;
if (file_exists($file)) {
    header('Content-Description: File Transfer');
    header("Content-Type:application/pdf");
    header('Content-Disposition: attachment; filename='.basename($file));
    header('Content-Transfer-Encoding: binary');
    header('Expires: 0');
    header('Cache-Control: must-revalidate');
    header('Pragma: public');
    header('Content-Length: ' . filesize($file));
    ob_clean();
    flush();
    readfile($file);
    exit;
} else {
    echo '<script>alert("下载的文件不存在");history.go(-1);</script>';
}

PDF文件格式的下载