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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。