PHP强制下载文件

函数：

function download($filename)
{ 
    if ((isset($filename))&&(file_exists($filename)))
    { 
       header("Content-length: ".filesize($filename)); 
       header('Content-Type: application/octet-stream'); 
       header('Content-Disposition: attachment; filename="' . $filename . '"'); 
       readfile("$filename"); 
    }
    else
    { 
       echo "Looks like file does not exist!"; 
    } 
}

使用方法：

download('shCoreDefault.css');