代码笔记 | PHP支持断点续传，分块下载的类

 <?php  /** * User: djunny * Date: 2016-04-29 * Time: 17:18 * Mail: [e-mail] * 支持断点下载的类 */class downloader {      /**     * download file to local path     *     * @param       $url     * @param       $save_file     * @param int   $speed     * @param array $headers     * @param int   $timeout     * @return bool     * @throws Exception     */    static function get($url, $save_file, $speed = 10240, $headers = array(), $timeout = 10) {        $url_info = self::parse_url($url);        if (!$url_info['host']) {            throw new Exception('Url is Invalid');        }          // default header        $def_headers = array(            'Accept'          => '*/*',            'User-Agent'      => 'Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.1; Trident/4.0)',            'Accept-Encoding' => 'gzip, deflate',            'Host'            => $url_info['host'],            'Connection'      => 'Close',            'Accept-Language' => 'zh-cn',        );          // merge heade        $headers = array_merge($def_headers, $headers);        // get content length        $content_length = self::get_content_size($url_info['host'], $url_info['port'], $url_info['request'], $headers, $timeout);          // content length not exist        if (!$content_length) {            throw new Exception('Content-Length is Not Exists');        }        // get exists length        $exists_length = is_file($save_file) ? filesize($save_file) : 0;        // get tmp data file        $data_file = $save_file . '.data';        // get tmp data        $exists_data = is_file($data_file) ? json_decode(file_get_contents($data_file), 1) : array();        // check file is valid        if ($exists_length == $content_length) {            $exists_data && @unlink($data_file);            return true;        }        // check file is expire        if ($exists_data['length'] != $content_length || $exists_length > $content_length) {            $exists_data = array(                'length' => $content_length,            );        }        // write exists data        file_put_contents($data_file, json_encode($exists_data));          try {            $download_status = self::download_content($url_info['host'], $url_info['port'], $url_info['request'], $save_file, $content_length, $exists_length, $speed, $headers, $timeout);            if ($download_status) {                @unlink($data_file);            }        } catch (Exception $e) {            throw new Exception($e->getMessage());        }        return true;    }      /**     * parse url     *     * @param $url     * @return bool|mixed     */    static function parse_url($url) {        $url_info = parse_url($url);        if (!$url_info['host']) {            return false;        }        $url_info['port']    = $url_info['port'] ? $url_info['host'] : 80;        $url_info['request'] = $url_info['path'] . ($url_info['query'] ? '?' . $url_info['query'] : '');        return $url_info;    }      /**     * download content by chunk     *     * @param $host     * @param $port     * @param $url_path     * @param $headers     * @param $timeout     */    static function download_content($host, $port, $url_path, $save_file, $content_length, $range_start, $speed, &$headers, $timeout) {        $request = self::build_header('GET', $url_path, $headers, $range_start);        $fsocket = @fsockopen($host, $port, $errno, $errstr, $timeout);        stream_set_blocking($fsocket, TRUE);        stream_set_timeout($fsocket, $timeout);        fwrite($fsocket, $request);        $status = stream_get_meta_data($fsocket);        if ($status['timed_out']) {            throw new Exception('Socket Connect Timeout');        }        $is_header_end = 0;        $total_size    = $range_start;        $file_fp       = fopen($save_file, 'a+');        while (!feof($fsocket)) {            if (!$is_header_end) {                $line = @fgets($fsocket);                if (in_array($line, array("\\n", "\\r\\n"))) {                    $is_header_end = 1;                }                continue;            }            $resp        = fread($fsocket, $speed);            $read_length = strlen($resp);            if ($resp === false || $content_length < $total_size + $read_length) {                fclose($fsocket);                fclose($file_fp);                throw new Exception('Socket I/O Error Or File Was Changed');            }            $total_size += $read_length;            fputs($file_fp, $resp);            // check file end            if ($content_length == $total_size) {                break;            }            sleep(1);            // for test            //break;        }        fclose($fsocket);        fclose($file_fp);        return true;      }      /**     * get content length     *     * @param $host     * @param $port     * @param $url_path     * @param $headers     * @param $timeout     * @return int     */    static function get_content_size($host, $port, $url_path, &$headers, $timeout) {        $request = self::build_header('HEAD', $url_path, $headers);        $fsocket = @fsockopen($host, $port, $errno, $errstr, $timeout);        stream_set_blocking($fsocket, TRUE);        stream_set_timeout($fsocket, $timeout);        fwrite($fsocket, $request);        $status = stream_get_meta_data($fsocket);        $length = 0;        if ($status['timed_out']) {            return 0;        }        while (!feof($fsocket)) {            $line = @fgets($fsocket);            if (in_array($line, array("\\n", "\\r\\n"))) {                break;            }            $line = strtolower($line);            // get location            if (substr($line, 0, 9) == 'location:') {                $location = trim(substr($line, 9));                $url_info = self::parse_url($location);                if (!$url_info['host']) {                    return 0;                }                fclose($fsocket);                return self::get_content_size($url_info['host'], $url_info['port'], $url_info['request'], $headers, $timeout);            }            // get content length            if (strpos($line, 'content-length:') !== false) {                list(, $length) = explode('content-length:', $line);                $length = (int)trim($length);            }        }        fclose($fsocket);        return $length;      }      /**     * build header for socket     *     * @param     $action     * @param     $url_path     * @param     $headers     * @param int $range_start     * @return string     */    static function build_header($action, $url_path, &$headers, $range_start = -1) {        $out = $action . " {$url_path} HTTP/1.0\\r\\n";        foreach ($headers as $hkey => $hval) {            $out .= $hkey . ': ' . $hval . "\\r\\n";        }        if ($range_start > -1) {            $out .= "Accept-Ranges: bytes\\r\\n";            $out .= "Range: bytes={$range_start}-\\r\\n";        }        $out .= "\\r\\n";          return $out;    }}    #use age/*try {    if (downloader::get('http://dzs.aqtxt.com/files/11/23636/201604230358308081.rar', 'test.rar')) {        //todo        echo 'Download Succ';    }} catch (Exception $e) {    echo 'Download Failed';}<pre name="code" class="php">*/

?>