content: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you under the Apache License, Version 2.0 (the
   * "License"); you may not use this file except in compliance
   * with the License.  You may obtain a copy of the License at
   *
   *    https://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing,
   * software distributed under the License is distributed on an
   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
   * KIND, either express or implied.  See the License for the
   * specific language governing permissions and limitations
   * under the License.
   */
  package org.apache.bigtop.manager.common.utils;
  
  import java.net.InetAddress;
  import java.net.UnknownHostException;
  
  public class NetUtils {
  
      private static InetAddress LOCAL_ADDRESS = null;
      private static volatile String HOST_ADDRESS;
      private static volatile String HOST_NAME;
  
      public static String getHost() {
          if (HOST_ADDRESS != null) {
              return HOST_ADDRESS;
          }
          try {
              InetAddress address = getLocalAddress();
              HOST_ADDRESS = address.getHostAddress();
              return HOST_ADDRESS;
          } catch (UnknownHostException e) {
              return "127.0.0.1";
          }
      }
  
      public static String getHostname() {
          if (HOST_NAME != null) {
              return HOST_NAME;
          }
          try {
              InetAddress address = getLocalAddress();
              HOST_NAME = address.getHostName();
              return HOST_NAME;
          } catch (UnknownHostException e) {
              return "localhost";
          }
      }
  
      private static InetAddress getLocalAddress() throws UnknownHostException {
          if (null != LOCAL_ADDRESS) {
              return LOCAL_ADDRESS;
          }
          LOCAL_ADDRESS = InetAddress.getLocalHost();
          return LOCAL_ADDRESS;
      }
  }
  