php 获取ip

//获取ip地址
public static function getIP() {
  if (@$_SERVER["HTTP_X_FORWARDED_FOR"])
        $ip = $_SERVER["HTTP_X_FORWARDED_FOR"];
  else if (@$_SERVER["HTTP_CLIENT_IP"])
       $ip = $_SERVER["HTTP_CLIENT_IP"];
else if (@$_SERVER["REMOTE_ADDR"])
       $ip = $_SERVER["REMOTE_ADDR"];
else if (@getenv("HTTP_X_FORWARDED_FOR"))
       $ip = getenv("HTTP_X_FORWARDED_FOR");
else if (@getenv("HTTP_CLIENT_IP"))
      $ip = getenv("HTTP_CLIENT_IP");
else if (@getenv("REMOTE_ADDR"))
      $ip = getenv("REMOTE_ADDR");
else
     $ip = "Unknown";
return $ip;
}