所謂斷點續傳，也就是要從文件已經下載的地方開始繼續下載。在以前版本的 HTTP 協議是不支持斷點的，HTTP/1.1 開始就支持了。一般斷點下載時才用到 Range 和 Content-Range 實體頭。 不使用斷點續傳 ~~~ get /down.zip http/1.1 accept: image/gif, image/x-xbitmap, image/jpeg, image/pjpeg, application/vnd.ms- excel, application/msword, application/vnd.ms-powerpoint, */* accept-language: zh-cn accept-encoding: gzip, deflate user-agent: mozilla/4.0 (compatible; msie 5.01; windows nt 5.0) connection: keep-alive ~~~ 服務器收到請求后，按要求尋找請求的文件，提取文件的信息，然后返回給瀏覽器，返回信息如下： ~~~ HTTP/1.1 200 Ok content-length=106786028 accept-ranges=bytes date=mon, 30 apr 2001 12:56:11 gmt etag=w/"02ca57e173c11:95b" content-type=application/octet-stream server=microsoft-iis/5.0 last-modified=mon, 30 apr 2001 12:56:11 gmt ~~~ 使用斷點續傳 ~~~ GET /down.zip HTTP/1.0 User-Agent: NetFox RANGE: bytes=2000070- Accept: text/html, image/gif, image/jpeg, *; q=.2, */*; q=.2 ~~~ 服務器收到這個請求以后，返回的信息如下： ~~~ HTTP/1.1 206 Partial Content content-length=106786028 content-range=bytes 2000070-106786027/106786028 date=mon, 30 apr 2001 12:55:20 gmt etag=w/"02ca57e173c11:95b" content-type=application/octet-stream server=microsoft-iis/5.0 last-modified=mon, 30 apr 2001 12:55:20 gmt ~~~ 和前面服務器返回的信息比較一下，就會發現增加了一行： `Content-Range=bytes 2000070-106786027/106786028` 返回的代碼也改為206了，而不再是200了。 `HTTP/1.1 206 Partial Content` PHP實現 ~~~ /** php下載類,支持斷點續傳 * download: 下載文件 * setSpeed: 設置下載速度 * getRange: 獲取header中Range */ class FileDownload{ /** 下載 * @param String $file 要下載的文件路徑 * @param String $name 文件名稱,為空則與下載的文件名稱一樣 * @param boolean $reload 是否開啟斷點續傳 */ public function download($file, $name='', $reload=false){ $fp = @fopen($file, 'rb'); if($fp){ if($name==''){ $name = basename($file); } $header_array = get_headers($file, true); //var_dump($header_array);die; // 下載本地文件，獲取文件大小 if (!$header_array) { $file_size = filesize($file); } else { $file_size = $header_array['Content-Length']; } $ranges = $this->getRange($file_size); $ua = $_SERVER["HTTP_USER_AGENT"];//判斷是什么類型瀏覽器 header('cache-control:public'); header('content-type:application/octet-stream'); $encoded_filename = urlencode($name); $encoded_filename = str_replace("+", "%20", $encoded_filename); //解決下載文件名亂碼 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 . '"'); } //header('Content-Disposition: attachment; filename="' . $name . '"'); if($reload && $ranges!=null){ // 使用續傳 header('HTTP/1.1 206 Partial Content'); header('Accept-Ranges:bytes'); // 剩余長度 header(sprintf('content-length:%u',$ranges['end']-$ranges['start'])); // range信息 header(sprintf('content-range:bytes %s-%s/%s', $ranges['start'], $ranges['end'], $file_size)); //file_put_contents('test.log',sprintf('content-length:%u',$ranges['end']-$ranges['start']),FILE_APPEND); // fp指針跳到斷點位置 fseek($fp, sprintf('%u', $ranges['start'])); }else{ file_put_contents('test.log','2222',FILE_APPEND); header('HTTP/1.1 200 OK'); header('content-length:'.$file_size); } while(!feof($fp)){ //echo fread($fp, round($this->_speed*1024,0)); //echo fread($fp, $file_size); echo fread($fp, 4096); ob_flush(); } ($fp!=null) && fclose($fp); }else{ return ''; } } /** 設置下載速度 * @param int $speed */ public function setSpeed($speed){ if(is_numeric($speed) && $speed>16 && $speed<4096){ $this->_speed = $speed; } } /** 獲取header range信息 * @param int $file_size 文件大小 * @return Array */ private function getRange($file_size){ //file_put_contents('range.log', json_encode($_SERVER), FILE_APPEND); if(isset($_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; } } $obj = new FileDownload(); $obj->download('http://down.golaravel.com/laravel/laravel-master.zip','', true); ~~~