Java tutorial
/** * * (C) Copyright 2008-2011 syslog4j.org * * All rights reserved. This program and the accompanying materials * are made available under the terms of the GNU Lesser General Public License * (LGPL) version 2.1 which accompanies this distribution, and is available at * http://www.gnu.org/licenses/lgpl-2.1.html * * This library is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. */ package com.nesscomputing.syslog4j.server; import static com.nesscomputing.syslog4j.SyslogConstants.TCP; import static com.nesscomputing.syslog4j.SyslogConstants.UDP; import java.util.Iterator; import java.util.Map; import java.util.Set; import org.apache.commons.lang3.StringUtils; import com.google.common.collect.Maps; import com.nesscomputing.syslog4j.SyslogConstants; import com.nesscomputing.syslog4j.SyslogRuntimeException; import com.nesscomputing.syslog4j.server.impl.net.tcp.TCPNetSyslogServerConfig; import com.nesscomputing.syslog4j.server.impl.net.udp.UDPNetSyslogServerConfig; import com.nesscomputing.syslog4j.util.SyslogUtility; /** * This class provides a Singleton-based interface for Syslog4j * server implementations. * * <p>Syslog4j is licensed under the Lesser GNU Public License v2.1. A copy * of the LGPL license is available in the META-INF folder in all * distributions of Syslog4j and in the base directory of the "doc" ZIP.</p> * * @author <syslog4j@productivity.org> * @version $Id: SyslogServer.java,v 1.14 2011/01/23 20:49:12 cvs Exp $ */ public class SyslogServer { private static boolean SUPPRESS_RUNTIME_EXCEPTIONS = false; protected static final Map<String, SyslogServerIF> instances = Maps.newHashMap(); static { initialize(); } private SyslogServer() { // } /** * @param suppress - true to suppress throwing SyslogRuntimeException in many methods of this class, false to throw exceptions (default) */ public static void setSuppressRuntimeExceptions(boolean suppress) { SUPPRESS_RUNTIME_EXCEPTIONS = suppress; } /** * @return Returns whether or not to suppress throwing SyslogRuntimeException in many methods of this class */ public static boolean getSuppressRuntimeExceptions() { return SUPPRESS_RUNTIME_EXCEPTIONS; } /** * Throws SyslogRuntimeException unless it has been suppressed via setSuppressRuntimeException(boolean). * * @param message * @throws SyslogRuntimeException */ private static void throwRuntimeException(String message) throws SyslogRuntimeException { if (SUPPRESS_RUNTIME_EXCEPTIONS) { return; } else { throw new SyslogRuntimeException(message.toString()); } } public static final SyslogServerIF getInstance(String protocol) throws SyslogRuntimeException { String syslogProtocol = protocol.toLowerCase(); if (instances.containsKey(syslogProtocol)) { return (SyslogServerIF) instances.get(syslogProtocol); } else { throwRuntimeException("SyslogServer instance \"" + syslogProtocol + "\" not defined; use \"tcp\" or \"udp\" or call SyslogServer.createInstance(protocol,config) first"); return null; } } public static final SyslogServerIF getThreadedInstance(String protocol) throws SyslogRuntimeException { SyslogServerIF server = getInstance(protocol); if (server.getThread() == null) { Thread thread = new Thread(server); thread.setName("SyslogServer: " + protocol); thread.setDaemon(server.getConfig().isUseDaemonThread()); if (server.getConfig().getThreadPriority() > -1) { thread.setPriority(server.getConfig().getThreadPriority()); } server.setThread(thread); thread.start(); } return server; } public static final boolean exists(String protocol) { if (StringUtils.isBlank(protocol)) { return false; } return instances.containsKey(protocol.toLowerCase()); } public static final SyslogServerIF createInstance(String protocol, SyslogServerConfigIF config) throws SyslogRuntimeException { if (StringUtils.isBlank(protocol)) { throwRuntimeException("Instance protocol cannot be null or empty"); return null; } if (config == null) { throwRuntimeException("SyslogServerConfig cannot be null"); return null; } String syslogProtocol = protocol.toLowerCase(); SyslogServerIF syslogServer = null; synchronized (instances) { if (instances.containsKey(syslogProtocol)) { throwRuntimeException("SyslogServer instance \"" + syslogProtocol + "\" already defined."); return null; } try { Class<? extends SyslogServerIF> syslogClass = config.getSyslogServerClass(); syslogServer = syslogClass.newInstance(); } catch (ClassCastException cse) { throw new SyslogRuntimeException(cse); } catch (IllegalAccessException iae) { throw new SyslogRuntimeException(iae); } catch (InstantiationException ie) { throw new SyslogRuntimeException(ie); } syslogServer.initialize(syslogProtocol, config); instances.put(syslogProtocol, syslogServer); } return syslogServer; } public static final SyslogServerIF createThreadedInstance(String protocol, SyslogServerConfigIF config) throws SyslogRuntimeException { createInstance(protocol, config); SyslogServerIF server = getThreadedInstance(protocol); return server; } public synchronized static final void destroyInstance(String protocol) { if (StringUtils.isBlank(protocol)) { return; } String _protocol = protocol.toLowerCase(); if (instances.containsKey(_protocol)) { SyslogUtility.sleep(SyslogConstants.THREAD_LOOP_INTERVAL_DEFAULT); SyslogServerIF syslogServer = (SyslogServerIF) instances.get(_protocol); try { syslogServer.shutdown(); } finally { instances.remove(_protocol); } } else { throwRuntimeException( "Cannot destroy server protocol \"" + protocol + "\" instance; call shutdown instead"); return; } } public synchronized static final void destroyInstance(SyslogServerIF syslogServer) { if (syslogServer == null) { return; } String protocol = syslogServer.getProtocol().toLowerCase(); if (instances.containsKey(protocol)) { SyslogUtility.sleep(SyslogConstants.THREAD_LOOP_INTERVAL_DEFAULT); try { syslogServer.shutdown(); } finally { instances.remove(protocol); } } else { throwRuntimeException( "Cannot destroy server protocol \"" + protocol + "\" instance; call shutdown instead"); } } public synchronized static void initialize() { createInstance(UDP, new UDPNetSyslogServerConfig()); createInstance(TCP, new TCPNetSyslogServerConfig()); } public synchronized static final void shutdown() throws SyslogRuntimeException { Set<String> protocols = instances.keySet(); Iterator<String> i = protocols.iterator(); while (i.hasNext()) { String protocol = i.next(); SyslogServerIF syslogServer = instances.get(protocol); syslogServer.shutdown(); } instances.clear(); } public static void main(String[] args) throws Exception { SyslogServerMain.main(args); } }