//此为下载文件

function download($file_dir,$file_name)

    {

        $file_dir = chop($file_dir);// remove of the more space

        // get the download file

        if($file_dir != '')

        {

            $file_path = $file_dir;

            if(substr($file_dir,strlen($file_dir)-1,strlen($file_dir)) != '/')

                $file_path .= '/';

            $file_path .= $file_name;

        }            

        else

            $file_path = $file_name;    

        

        // judge the download file exist

        if(!file_exists($file_path))

        {

            echo 'Sorry,the file not exist';

            exit;

        }

        

        $file_size = filesize($file_path);

       

        header("Content-type: application/octet-stream");

        header("Accept-Ranges: bytes");

        header("Accept-Length: $file_size");

        header("Content-Disposition: attachment; filename=".$file_name);

        

        $fp = fopen($file_path,"r");

        $buffer_size = 1024;

        $cur_pos = 0;

        

        while(!feof($fp)&&$file_size-$cur_pos>$buffer_size)

        {

            $buffer = fread($fp,$buffer_size);

            echo $buffer;

            $cur_pos += $buffer_size;

        }

        

        $buffer = fread($fp,$file_size-$cur_pos);

        echo $buffer;

        fclose($fp);

    }

	$file_path = "../data/";