文件下载

<?php
$file="D:/AppServ/www/a.txt";
if(is_file($file)) {
            header("Content-Type: application/force-download");
            header("Content-Disposition: attachment; filename=".basename($file));
            readfile($file);
            exit;
        }else{
            echo "文件不存在！";
            exit;
        }
?>