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Spring Framework example source code file (CachingConnectionFactory.java)

This example Spring Framework source code file (CachingConnectionFactory.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Spring Framework tags/keywords

cachedsessioninvocationhandler, cachedsessioninvocationhandler, cachingconnectionfactory, created, found, hashmap, linkedlist, linkedlist, map, messageproducer, messageproducer, object, reflection, session, session, util

The Spring Framework CachingConnectionFactory.java source code

/*
 * Copyright 2002-2008 the original author or authors.
 *
 * Licensed 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
 *
 *      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.springframework.jms.connection;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;

import javax.jms.Connection;
import javax.jms.Destination;
import javax.jms.JMSException;
import javax.jms.MessageProducer;
import javax.jms.QueueSession;
import javax.jms.Session;
import javax.jms.TopicSession;

import org.springframework.util.Assert;

/**
 * {@link SingleConnectionFactory} subclass that adds {@link javax.jms.Session}
 * caching as well {@link javax.jms.MessageProducer} caching. This ConnectionFactory
 * also switches the {@link #setReconnectOnException "reconnectOnException" property}
 * to "true" by default, allowing for automatic recovery of the underlying Connection.
 *
 * <p>By default, only one single Session will be cached, with further requested
 * Sessions being created and disposed on demand. Consider raising the
 * {@link #setSessionCacheSize "sessionCacheSize" value} in case of a
 * high-concurrency environment.
 *
 * <p>NOTE: This ConnectionFactory decorator requires JMS 1.1 or higher.
 * For JMS 1.0.2, consider using {@link SingleConnectionFactory102} instead.
 *
 * @author Juergen Hoeller
 * @since 2.5.3
 */
public class CachingConnectionFactory extends SingleConnectionFactory {

	private int sessionCacheSize = 1;

	private boolean cacheProducers = true;

	private final Map cachedSessions = new HashMap();


	public CachingConnectionFactory() {
		setReconnectOnException(true);
	}


	/**
	 * Specify the desired size for the JMS Session cache (per JMS Session type).
	 * <p>This cache size is the maximum limit for the number of cached Sessions
	 * per session acknowledgement type (auto, client, dups_ok, transacted).
	 * As a consequence, the actual number of cached Sessions may be up to
	 * four times as high as the specified value - in the unlikely case
	 * of mixing and matching different acknowledgement types.
	 * <p>Default is 1: caching a single Session, (re-)creating further ones on
	 * demand. Specify a number like 10 if you'd like to raise the number of cached
	 * Sessions; that said, 1 may be sufficient for low-concurrency scenarios.
	 * @see #setCacheProducers
	 */
	public void setSessionCacheSize(int sessionCacheSize) {
		Assert.isTrue(sessionCacheSize >= 1, "Session cache size must be 1 or higher");
		this.sessionCacheSize = sessionCacheSize;
	}

	/**
	 * Return the desired size for the JMS Session cache (per JMS Session type).
	 */
	public int getSessionCacheSize() {
		return this.sessionCacheSize;
	}

	/**
	 * Specify whether to cache JMS MessageProducers per JMS Session instance
	 * (more specifically: one MessageProducer per Destination and Session).
	 * <p>Default is "true". Switch this to "false" in order to recreate
	 * MessageProducers on demand.
	 */
	public void setCacheProducers(boolean cacheProducers) {
		this.cacheProducers = cacheProducers;
	}

	/**
	 * Return whether to cache JMS MessageProducers per JMS Session instance.
	 */
	public boolean isCacheProducers() {
		return this.cacheProducers;
	}


	/**
	 * Resets the Session cache as well.
	 */
	public void resetConnection() {
		synchronized (this.cachedSessions) {
			this.cachedSessions.clear();
		}
		super.resetConnection();
	}

	/**
	 * Checks for a cached Session for the given mode.
	 */
	protected Session getSession(Connection con, Integer mode) throws JMSException {
		LinkedList sessionList = null;
		synchronized (this.cachedSessions) {
			sessionList = (LinkedList) this.cachedSessions.get(mode);
			if (sessionList == null) {
				sessionList = new LinkedList();
				this.cachedSessions.put(mode, sessionList);
			}
		}
		Session session = null;
		synchronized (sessionList) {
			if (!sessionList.isEmpty()) {
				session = (Session) sessionList.removeFirst();
			}
		}
		if (session != null) {
			if (logger.isDebugEnabled()) {
				logger.debug("Found cached Session for mode " + mode + ": " + session);
			}
		}
		else {
			boolean transacted = (mode.intValue() == Session.SESSION_TRANSACTED);
			int ackMode = (transacted ? Session.AUTO_ACKNOWLEDGE : mode.intValue());
			Session targetSession = con.createSession(transacted, ackMode);
			session = getCachedSessionProxy(targetSession, sessionList);
			if (logger.isDebugEnabled()) {
				logger.debug("Created cached Session for mode " + mode + ": " + session);
			}
		}
		return session;
	}

	/**
	 * Wrap the given Session with a proxy that delegates every method call to it
	 * but adapts close calls. This is useful for allowing application code to
	 * handle a special framework Session just like an ordinary Session.
	 * @param target the original Session to wrap
	 * @param sessionList the List of cached Sessions that the given Session belongs to
	 * @return the wrapped Session
	 */
	protected Session getCachedSessionProxy(Session target, LinkedList sessionList) {
		List classes = new ArrayList(3);
		classes.add(Session.class);
		if (target instanceof QueueSession) {
			classes.add(QueueSession.class);
		}
		if (target instanceof TopicSession) {
			classes.add(TopicSession.class);
		}
		return (Session) Proxy.newProxyInstance(
				getClass().getClassLoader(),
				(Class[]) classes.toArray(new Class[classes.size()]),
				new CachedSessionInvocationHandler(target, sessionList));
	}


	/**
	 * Invocation handler for a cached JMS Session proxy.
	 */
	private class CachedSessionInvocationHandler implements InvocationHandler {

		private final Session target;

		private final LinkedList sessionList;

		private final Map cachedProducers = new HashMap();

		public CachedSessionInvocationHandler(Session target, LinkedList sessionList) {
			this.target = target;
			this.sessionList = sessionList;
		}

		public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
			if (method.getName().equals("equals")) {
				// Only consider equal when proxies are identical.
				return (proxy == args[0] ? Boolean.TRUE : Boolean.FALSE);
			}
			else if (method.getName().equals("hashCode")) {
				// Use hashCode of Connection proxy.
				return new Integer(hashCode());
			}
			else if (method.getName().equals("close")) {
				// Handle close method: don't pass the call on.
				synchronized (this.sessionList) {
					if (this.sessionList.size() < getSessionCacheSize()) {
						if (!this.sessionList.contains(proxy)) {
							this.sessionList.addLast(proxy);
							if (logger.isDebugEnabled()) {
								logger.debug("Returned cached Session: " + proxy);
							}
						}
						return null;
					}
					else {
						for (Iterator it = this.cachedProducers.values().iterator(); it.hasNext();) {
							((MessageProducer) it.next()).close();
						}
						this.target.close();
						if (logger.isDebugEnabled()) {
							logger.debug("Closed cached Session: " + proxy);
						}
						return null;
					}
				}
			}
			else if ((method.getName().equals("createProducer") || method.getName().equals("createSender") ||
					method.getName().equals("createPublisher")) && isCacheProducers()) {
				Destination dest = (Destination) args[0];
				MessageProducer producer = (MessageProducer) this.cachedProducers.get(dest);
				if (producer != null) {
					if (logger.isDebugEnabled()) {
						logger.debug("Found cached MessageProducer for destination [" + dest + "]: " + producer);
					}
				}
				else {
					producer = this.target.createProducer(dest);
					this.cachedProducers.put(dest, producer);
					if (logger.isDebugEnabled()) {
						logger.debug("Created cached MessageProducer for destination [" + dest + "]: " + producer);
					}
				}
				return new CachedMessageProducer(producer);
			}
			try {
				return method.invoke(this.target, args);
			}
			catch (InvocationTargetException ex) {
				throw ex.getTargetException();
			}
		}
	}

}

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