php支持断点续传、分块下载的类

本文是为大家分享php支持断点续传、分块下载的类，供大家参考，具体内容如下

    <?php

    /**
     * User: djunny
     * Date: 2016-04-29
     * Time: 17:18
     * Mail: 199962760@qq.com
     * 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';
    }
    */
    ?>

以上就是本文的全部内容，希望对大家的学习有所帮助。