php 续传 下载类

$obj = new FileDownload();$flag = $obj->download($fileUrl, $fileName);//fileUrl是下载地址，fileName是下载之后文件的名称 包括后缀名  如：hello.mp4class FileDownload{   /** 下载    * @param String  $file   要下载的文件路径    * @param String  $name   文件名称,为空则与下载的文件名称一样    * @param boolean $reload 是否开启断点续传    */    public function download($file, $name='', $reload=false){        $fp = @fopen($file, 'rb');if($fp){            if($name==''){                $name = basename($file);            }        $header_array = get_headers($file, true);$file_size = $header_array['Content-Length'];            $ranges = $this->getRange($file_size);            $ua = $_SERVER["HTTP_USER_AGENT"];//判断是什么类型浏览器            header('cache-control:public');            header('content-type:application/octet-stream');            $encoded_filename = urlencode($name);$encoded_filename = str_replace("+", "%20", $encoded_filename);               //解决下载文件名乱码if (preg_match("/MSIE/", $ua) ||  preg_match("/Trident/", $ua) ){header('Content-Disposition: attachment; filename="' .$encoded_filename . '"');} else if (preg_match("/Firefox/", $ua)) {header('Content-Disposition: attachment; filename*="utf8\'\'' . $name . '"');}else if (preg_match("/Chrome/", $ua)) {header('Content-Disposition: attachment; filename="' . $encoded_filename . '"');} else {header('Content-Disposition: attachment; filename="' . $name . '"');}               if($reload && $ranges!=null){ // 使用续传                header('HTTP/1.1 206 Partial Content');                header('Accept-Ranges:bytes');                                // 剩余长度                header(sprintf('content-length:%u',$ranges['end']-$ranges['start']));                                // range信息                header(sprintf('content-range:bytes %s-%s/%s', $ranges['start'], $ranges['end'], $file_size));                                // fp指针跳到断点位置                fseek($fp, sprintf('%u', $ranges['start']));            }else{                header('HTTP/1.1 200 OK');                header('content-length:'.$file_size);            }            while(!feof($fp)){ob_clean();echo fread($fp, 4096);                //echo fread($fp, round($this->_speed*1024,0));                //echo fread($fp, $file_size);                ob_flush();            }            ($fp!=null) && fclose($fp);        }else{            return '';        }    }   /** 设置下载速度    * @param int $speed    */    public function setSpeed($speed){        if(is_numeric($speed) && $speed>16 && $speed<4096){            $this->_speed = $speed;        }    }   /** 获取header range信息    * @param  int   $file_size 文件大小    * @return Array    */    private function getRange($file_size){        if(isset($_SERVER['HTTP_RANGE']) && !empty($_SERVER['HTTP_RANGE'])){            $range = $_SERVER['HTTP_RANGE'];            $range = preg_replace('/[\s|,].*/', '', $range);            $range = explode('-', substr($range, 6));            if(count($range)<2){                $range[1] = $file_size;            }            $range = array_combine(array('start','end'), $range);            if(empty($range['start'])){                $range['start'] = 0;            }            if(empty($range['end'])){                $range['end'] = $file_size;            }            return $range;        }        return null;    }}