php实现文件下载

    //文件下载

    public function download_file($id){

    header("Content-type:text/html;charset=utf-8");

    $url = M('','',MYSQL_READ)->table('artical_attachment')->where(array('id'=>$id))->getField('url');

    $ex_url = explode('/',$url);

    //p($url);exit();

    $file_name=$ex_url[5];

    $file_name=iconv("utf-8","gb2312",$file_name);

    if(!file_exists($url)){

    $this->error('没有该文件!');

    return;

    }

    $fp = fopen($url,'r');

    $file_size = filesize($url);

    //下载文件需要用到的头

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

    Header("Accept-Ranges: bytes");

    Header("Accept-Length:".$file_size);

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

    $buffer=1024;

    $file_count=0;

    //向浏览器返回数据

    while(!feof($fp) && $file_count<$file_size){

    $file_con=fread($fp,$buffer);

    $file_count+=$buffer;

    echo $file_con;

    }

    fclose($fp);

    }