php 点击下载文件

//下载文件
public function download(Request $request){
    $file_path = 'C:/Users/Admin/Desktop/办公材料/缓存.txt';
    $file_name = '缓存.txt';

    if (!file_exists($file_path)) {
        echo '文件不存在';
        exit();
    }

    header('Content-Type: application/pdf');
    header('Content-Disposition: attachment; filename='.$file_name);

    readfile($file_path);
}