一个Java获取主机名的方法

本文无技术要点，仅为备忘。

@NoArgsConstructor(access = AccessLevel.PRIVATE)
public class HostNameUtil {

  private static String hostName;

  public static String getHostName() throws UnknownHostException {
    if (hostName != null) {
      return hostName;
    }
    synchronized (HostNameUtil.class) {
      if (hostName == null) {
        InetAddress inet = InetAddress.getLocalHost();
        hostName = inet.getHostName();
      }
    }
    return hostName;
  }

}