001/** 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017package org.apache.activemq.util; 018 019import java.net.InetAddress; 020import java.net.UnknownHostException; 021 022public class InetAddressUtil { 023 024 /** 025 * When using the {@link java.net.InetAddress#getHostName()} method in an 026 * environment where neither a proper DNS lookup nor an <tt>/etc/hosts</tt> 027 * entry exists for a given host, the following exception will be thrown: 028 * <code> 029 * java.net.UnknownHostException: <hostname>: <hostname> 030 * at java.net.InetAddress.getLocalHost(InetAddress.java:1425) 031 * ... 032 * </code> 033 * Instead of just throwing an UnknownHostException and giving up, this 034 * method grabs a suitable hostname from the exception and prevents the 035 * exception from being thrown. If a suitable hostname cannot be acquired 036 * from the exception, only then is the <tt>UnknownHostException</tt> thrown. 037 * 038 * @return The hostname 039 * @throws UnknownHostException 040 * @see {@link java.net.InetAddress#getLocalHost()} 041 * @see {@link java.net.InetAddress#getHostName()} 042 */ 043 public static String getLocalHostName() throws UnknownHostException { 044 try { 045 return (InetAddress.getLocalHost()).getHostName(); 046 } catch (UnknownHostException uhe) { 047 String host = uhe.getMessage(); // host = "hostname: hostname" 048 if (host != null) { 049 int colon = host.indexOf(':'); 050 if (colon > 0) { 051 return host.substring(0, colon); 052 } 053 } 054 throw uhe; 055 } 056 } 057}