• 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'],$content_length,$exists_length,$speed,$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,$range_start,&$headers,$timeout) {
  $request = self::build_header('GET',$range_start);
  $fsocket = @fsockopen($host,$errno,$errstr,$timeout);
  stream_set_blocking($fsocket,TRUE);
  stream_set_timeout($fsocket,$timeout);
  fwrite($fsocket,$request);
  $status = streamgetMeta_data($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,$timeout) {
  $request = self::build_header('HEAD',$headers);
  $fsocket = @fsockopen($host,$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,"\r\n"))) {
  break;
  }
  $line = strtolower($line);
  // get location
  if (substr($line,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($url_info['host'],$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,$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';
}
/
?>