Java tutorial
/** * Licensed to Apereo under one or more contributor license * agreements. See the NOTICE file distributed with this work * for additional information regarding copyright ownership. * Apereo 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 the following location: * * http://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.apereo.portal; import java.net.InetAddress; import java.net.NetworkInterface; import java.net.SocketException; import java.net.UnknownHostException; import java.util.Collections; import java.util.Enumeration; import java.util.LinkedHashSet; import java.util.Set; import java.util.UUID; import java.util.concurrent.locks.ReadWriteLock; import java.util.concurrent.locks.ReentrantReadWriteLock; import org.apache.commons.lang.StringUtils; import org.apereo.portal.utils.RandomTokenGenerator; import org.apereo.portal.utils.threading.ReadResult; import org.apereo.portal.utils.threading.ReadWriteCallback; import org.apereo.portal.utils.threading.ReadWriteLockTemplate; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.beans.factory.annotation.Value; import org.springframework.stereotype.Service; /** * @author Eric Dalquist * @version $Revision$ */ @Service("portalInfoProvider") public class PortalInfoProviderImpl implements IPortalInfoProvider, ReadWriteCallback<String> { protected final Logger logger = LoggerFactory.getLogger(getClass()); private String serverName; private String networkInterfaceName; private String resolvedServerName; private String resolvedUniqueServerName; /** * @param serverName A specific server name for {@link #getServerName()} to return */ @Value("${org.apereo.portal.PortalInfoProvider.serverName:}") public void setServerName(String serverName) { this.serverName = StringUtils.trimToNull(serverName); } /** * @param networkInterfaceName The name to use to lookup a NetworkInterface via {@link NetworkInterface#getByName(String)} */ @Value("${org.apereo.portal.PortalInfoProvider.networkInterfaceName:}") public void setNetworkInterfaceName(String networkInterfaceName) { this.networkInterfaceName = StringUtils.trimToNull(networkInterfaceName); } private final ReadWriteLock serverNameResolutionLock = new ReentrantReadWriteLock(); @Override public final String getServerName() { return ReadWriteLockTemplate.doWithLock(serverNameResolutionLock, this); } @Override public String getUniqueServerName() { ReadWriteLockTemplate.doWithLock(serverNameResolutionLock, this); return this.resolvedUniqueServerName; } @Override public ReadResult<String> doInReadLock() { if (this.resolvedServerName != null) { return ReadResult.create(false, this.resolvedServerName); } return ReadResult.create(true); } @Override public String doInWriteLock(ReadResult<String> readResult) { this.resolvedServerName = resolveServerName(); this.resolvedUniqueServerName = this.resolvedServerName + "_" + RandomTokenGenerator.INSTANCE.generateRandomToken(4); return this.resolvedServerName; } protected String resolveServerName() { if (this.serverName != null) { return this.serverName; } String name = getNetworkInterfaceName(this.networkInterfaceName); if (name != null) { return name; } name = getLocalHostName(); if (name != null) { return name; } name = getDefaultNetworkInterfaceName(); if (name != null) { return name; } this.logger.warn("Failed to get serverName for NetworkInterface (" + this.networkInterfaceName + "), for InetAddress.getLocalHost(), for any NetworkInterface. Reverting to JVM instance specific UUID string."); return UUID.randomUUID().toString(); } protected String getDefaultNetworkInterfaceName() { this.logger .info("Attempting to resolve serverName by iterating over NetworkInterface.getNetworkInterfaces()"); //Fail back to our best attempt at resolution final Enumeration<NetworkInterface> networkInterfaceEnum; try { networkInterfaceEnum = NetworkInterface.getNetworkInterfaces(); } catch (SocketException e) { logger.warn("Failed to get list of available NetworkInterfaces.", e); return null; } //Use a local variable here to try and return the first hostName found that doesn't start with localhost String name = null; while (networkInterfaceEnum.hasMoreElements()) { final NetworkInterface networkInterface = networkInterfaceEnum.nextElement(); for (Enumeration<InetAddress> inetAddressEnum = networkInterface.getInetAddresses(); inetAddressEnum .hasMoreElements();) { final InetAddress inetAddress = inetAddressEnum.nextElement(); name = inetAddress.getHostName(); if (!name.startsWith("localhost")) { return name; } } } return name; } protected String getLocalHostName() { this.logger.info("Attempting to resolve serverName using InetAddress.getLocalHost()"); final InetAddress localhost; try { localhost = InetAddress.getLocalHost(); } catch (UnknownHostException e) { logger.warn("Failed to find InetAddress for InetAddress.getLocalHost()", e); return null; } return localhost.getHostName(); } protected String getNetworkInterfaceName(String networkInterfaceName) { if (networkInterfaceName == null) { return null; } this.logger.info("Attempting to resolve serverName using NetworkInterface named ({})", networkInterfaceName); final NetworkInterface networkInterface; try { networkInterface = NetworkInterface.getByName(networkInterfaceName); } catch (SocketException e) { logger.warn("Failed to get NetworkInterface for name (" + networkInterfaceName + ").", e); return null; } if (networkInterface == null) { logger.warn("No NetworkInterface could be found for name (" + networkInterfaceName + "). Available interface names: " + getNetworkInterfaceNames()); return null; } final Enumeration<InetAddress> inetAddressesEnum = networkInterface.getInetAddresses(); if (!inetAddressesEnum.hasMoreElements()) { logger.warn("NetworkInterface (" + networkInterface.getName() + ") has no InetAddresses to get a name from."); return null; } final InetAddress inetAddress = inetAddressesEnum.nextElement(); if (inetAddressesEnum.hasMoreElements()) { logger.warn("NetworkInterface (" + networkInterface.getName() + ") has more than one InetAddress, the hostName of the first will be returned."); } return inetAddress.getHostName(); } protected Set<String> getNetworkInterfaceNames() { final Enumeration<NetworkInterface> networkInterfacesEnum; try { networkInterfacesEnum = NetworkInterface.getNetworkInterfaces(); } catch (SocketException e) { logger.warn("Failed to get list of available NetworkInterfaces.", e); return Collections.emptySet(); } final Set<String> names = new LinkedHashSet<String>(); while (networkInterfacesEnum.hasMoreElements()) { final NetworkInterface networkInterface = networkInterfacesEnum.nextElement(); names.add(networkInterface.getName()); } return names; } }