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 */ 017 package org.apache.camel.util; 018 019 import java.net.InetAddress; 020 import java.net.UnknownHostException; 021 022 /** 023 * Util class for {@link java.net.InetAddress} 024 */ 025 public final class InetAddressUtil { 026 027 private InetAddressUtil() { 028 // util class 029 } 030 031 /** 032 * When using the {@link java.net.InetAddress#getHostName()} method in an 033 * environment where neither a proper DNS lookup nor an <tt>/etc/hosts</tt> 034 * entry exists for a given host, the following exception will be thrown: 035 * <p/> 036 * <code> 037 * java.net.UnknownHostException: <hostname>: <hostname> 038 * at java.net.InetAddress.getLocalHost(InetAddress.java:1425) 039 * ... 040 * </code> 041 * <p/> 042 * Instead of just throwing an UnknownHostException and giving up, this 043 * method grabs a suitable hostname from the exception and prevents the 044 * exception from being thrown. If a suitable hostname cannot be acquired 045 * from the exception, only then is the <tt>UnknownHostException</tt> thrown. 046 * 047 * @return the hostname 048 * @throws UnknownHostException is thrown if hostname could not be resolved 049 */ 050 public static String getLocalHostName() throws UnknownHostException { 051 try { 052 return (InetAddress.getLocalHost()).getHostName(); 053 } catch (UnknownHostException uhe) { 054 String host = uhe.getMessage(); // host = "hostname: hostname" 055 if (host != null) { 056 int colon = host.indexOf(':'); 057 if (colon > 0) { 058 return host.substring(0, colon); 059 } 060 } 061 throw uhe; 062 } 063 } 064 065 }