header 头各种类型文件下载

function down_file($url,$type='application/zip'){
    header("Cache-Control: public"); 
    header("Content-Description: File Transfer"); 
    header('Content-disposition: attachment; filename='.basename($url)); //文件名   
    header("Content-Type: ".$type); //zip格式的   
    header("Content-Transfer-Encoding: binary"); //告诉浏览器，这是二进制文件    
    header('Content-Length: '. filesize($url)); //告诉浏览器，文件大小   
    @readfile($url);
}