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.camel.util; 018 019import java.net.InetAddress; 020import java.net.UnknownHostException; 021 022/** 023 * Util class for {@link java.net.InetAddress} 024 */ 025public 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 environment where neither a proper DNS 033 * lookup nor an <tt>/etc/hosts</tt> entry exists for a given host, the following exception will be thrown: 034 * <p/> 035 * <code> 036 * java.net.UnknownHostException: <hostname>: <hostname> 037 * at java.net.InetAddress.getLocalHost(InetAddress.java:1425) 038 * ... 039 * </code> 040 * <p/> 041 * Instead of just throwing an UnknownHostException and giving up, this method grabs a suitable hostname from the 042 * exception and prevents the exception from being thrown. If a suitable hostname cannot be acquired from the 043 * exception, only then is the <tt>UnknownHostException</tt> thrown. 044 * 045 * @return the hostname 046 * @throws UnknownHostException is thrown if hostname could not be resolved 047 */ 048 public static String getLocalHostName() throws UnknownHostException { 049 try { 050 return (InetAddress.getLocalHost()).getHostName(); 051 } catch (UnknownHostException uhe) { 052 String host = uhe.getMessage(); // host = "hostname: hostname" 053 if (host != null) { 054 int colon = host.indexOf(':'); 055 if (colon > 0) { 056 return host.substring(0, colon); 057 } 058 } 059 throw uhe; 060 } 061 } 062 063 /** 064 * When using the {@link java.net.InetAddress#getHostName()} method in an environment where neither a proper DNS 065 * lookup nor an <tt>/etc/hosts</tt> entry exists for a given host, the following exception will be thrown: 066 * <p/> 067 * <code> 068 * java.net.UnknownHostException: <hostname>: <hostname> 069 * at java.net.InetAddress.getLocalHost(InetAddress.java:1425) 070 * ... 071 * </code> 072 * <p/> 073 * Instead of just throwing an UnknownHostException and giving up, this method grabs a suitable hostname from the 074 * exception and prevents the exception from being thrown. If a suitable hostname cannot be acquired from the 075 * exception, then <tt>null</tt> is returned 076 * 077 * @return the hostname, or <tt>null</tt> if not possible to resolve 078 */ 079 public static String getLocalHostNameSafe() { 080 try { 081 return getLocalHostName(); 082 } catch (Exception e) { 083 // ignore 084 } 085 return null; 086 } 087 088}