注意，此方法运行缓慢，切不可在大量访问处使用！或者请使用缓存！

感谢 http://snowcoal.com/article/324.html

function ip_info($ip = NULL, $purpose = "location", $deep_detect = TRUE) {
  $output = NULL;
  if (filter_var($ip, FILTER_VALIDATE_IP) === FALSE) {
    $ip = $_SERVER["REMOTE_ADDR"];
    if ($deep_detect) {
      if (filter_var(@$_SERVER['HTTP_X_FORWARDED_FOR'], FILTER_VALIDATE_IP))
        $ip = $_SERVER['HTTP_X_FORWARDED_FOR'];
      if (filter_var(@$_SERVER['HTTP_CLIENT_IP'], FILTER_VALIDATE_IP))
        $ip = $_SERVER['HTTP_CLIENT_IP'];
    }
  }
  $purpose  = str_replace(array("name", "\n", "\t", " ", "-", "_"), NULL, strtolower(trim($purpose)));
  $support  = array("country", "countrycode", "state", "region", "city", "location", "address");
  $continents = array(
    "AF" => "Africa",
    "AN" => "Antarctica",
    "AS" => "Asia",
    "EU" => "Europe",
    "OC" => "Australia (Oceania)",
    "NA" => "North America",
    "SA" => "South America"
  );
  if (filter_var($ip, FILTER_VALIDATE_IP) && in_array($purpose, $support)) {
    $ipdat = @json_decode(file_get_contents("http://www.geoplugin.net/json.gp?ip=" . $ip));
    if (@strlen(trim($ipdat->geoplugin_countryCode)) == 2) {
      switch ($purpose) {
        case "location":
          $output = array(
            "city"      => @$ipdat->geoplugin_city,
            "state"     => @$ipdat->geoplugin_regionName,
            "country"    => @$ipdat->geoplugin_countryName,
            "country_code"  => @$ipdat->geoplugin_countryCode,
            "continent"   => @$continents[strtoupper($ipdat->geoplugin_continentCode)],
            "continent_code" => @$ipdat->geoplugin_continentCode
          );
          break;
        case "address":
          $address = array($ipdat->geoplugin_countryName);
          if (@strlen($ipdat->geoplugin_regionName) >= 1)
            $address[] = $ipdat->geoplugin_regionName;
          if (@strlen($ipdat->geoplugin_city) >= 1)
            $address[] = $ipdat->geoplugin_city;
          $output = implode(", ", array_reverse($address));
          break;
        case "city":
          $output = @$ipdat->geoplugin_city;
          break;
        case "state":
          $output = @$ipdat->geoplugin_regionName;
          break;
        case "region":
          $output = @$ipdat->geoplugin_regionName;
          break;
        case "country":
          $output = @$ipdat->geoplugin_countryName;
          break;
        case "countrycode":
          $output = @$ipdat->geoplugin_countryCode;
          break;
      }
    }
  }
  return $output;
}