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.activemq.web; 018 019 import java.util.LinkedList; 020 021 import javax.jms.Connection; 022 import javax.jms.ConnectionFactory; 023 import javax.jms.JMSException; 024 import javax.jms.Session; 025 026 /** 027 * A simple pool of JMS Session objects intended for use by Queue browsers. 028 * 029 * @version $Revision: 569067 $ 030 */ 031 public class SessionPool { 032 033 private ConnectionFactory connectionFactory; 034 private Connection connection; 035 private LinkedList<Session> sessions = new LinkedList<Session>(); 036 037 public Connection getConnection() throws JMSException { 038 if (checkConnection()) { 039 return connection; 040 } 041 042 synchronized (this) { 043 connection = getConnectionFactory().createConnection(); 044 connection.start(); 045 return connection; 046 } 047 } 048 049 private boolean checkConnection() { 050 if (connection == null) { 051 return false; 052 } 053 054 try { 055 connection.getMetaData(); 056 return true; 057 } catch (JMSException e) { 058 return false; 059 } 060 } 061 062 public void setConnection(Connection connection) { 063 this.connection = connection; 064 } 065 066 public ConnectionFactory getConnectionFactory() { 067 if (connectionFactory == null) { 068 throw new IllegalStateException("No ConnectionFactory has been set for the session pool"); 069 } 070 return connectionFactory; 071 } 072 073 public void setConnectionFactory(ConnectionFactory connectionFactory) { 074 this.connectionFactory = connectionFactory; 075 } 076 077 public Session borrowSession() throws JMSException { 078 Session answer = null; 079 synchronized (sessions) { 080 if (sessions.isEmpty()) { 081 answer = createSession(); 082 } else { 083 answer = sessions.removeLast(); 084 } 085 } 086 return answer; 087 } 088 089 public void returnSession(Session session) { 090 if (session != null) { 091 synchronized (sessions) { 092 sessions.add(session); 093 } 094 } 095 } 096 097 protected Session createSession() throws JMSException { 098 return getConnection().createSession(false, Session.AUTO_ACKNOWLEDGE); 099 } 100 101 }