hermes.store.jdbc.MessageResultSetHandler.java Source code

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Here is the source code for hermes.store.jdbc.MessageResultSetHandler.java

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/* 
 * Copyright 2003,2004,2005 Colin Crist
 *
 * 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 hermes.store.jdbc;

import hermes.Domain;
import hermes.HermesRuntimeException;
import hermes.MessageFactory;
import hermes.impl.DefaultXMLHelper;
import hermes.impl.XMLHelper;
import hermes.store.MessageStore;
import hermes.store.MessageStoreQueue;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Enumeration;
import java.util.List;

import javax.jms.Destination;
import javax.jms.JMSException;
import javax.jms.Message;
import javax.jms.Queue;
import javax.jms.QueueBrowser;
import javax.naming.NamingException;

import org.apache.commons.dbutils.DbUtils;
import org.apache.log4j.Logger;

/**
 * @author colincrist@hermesjms.com
 * @version $Id: MessageResultSetHandler.java,v 1.2 2005/08/15 20:37:34 colincrist Exp $
 */

public class MessageResultSetHandler implements QueueBrowser {
    private static final Logger log = Logger.getLogger(MessageResultSetHandler.class);
    private ResultSet resultSet;
    private List<Message> cachedMessages = new ArrayList<Message>();
    private XMLHelper xmlHelper = new DefaultXMLHelper();
    private MessageFactory messageFactory;
    private Connection connection;
    private MessageStore.HeaderPolicy headerPolicy;
    private PreparedStatement statement;
    private boolean resultSetEmpty = false;
    private Enumeration enumeration;

    public MessageResultSetHandler(Connection connection, PreparedStatement statement,
            MessageFactory messageFactory, MessageStore.HeaderPolicy headerPolicy) throws SQLException {
        this.connection = connection;
        this.messageFactory = messageFactory;
        this.headerPolicy = headerPolicy;
        this.statement = statement;
        this.resultSet = statement.executeQuery();

        enumeration = new Enumeration() {

            public Object nextElement() {
                return getNextMessageQuietly();
            }

            public boolean hasMoreElements() {
                return hasNextMessage();
            }

        };
    }

    public boolean hasNextMessage() {
        return !resultSetEmpty || cachedMessages.size() > 0;
    }

    public Message getNextMessage() throws JMSException, SQLException, NamingException {
        if (cachedMessages.size() > 0) {
            return cachedMessages.remove(0);
        } else {
            if (resultSet.next()) {
                final Collection<Message> c = xmlHelper.fromXML(messageFactory,
                        resultSet.getClob(3).getAsciiStream());

                for (Message m : c) {
                    if (headerPolicy != MessageStore.HeaderPolicy.NO_HEADER) {
                        Destination d = messageFactory.getDestination(resultSet.getString(1),
                                Domain.getDomain(resultSet.getInt(2)));

                        if (headerPolicy == MessageStore.HeaderPolicy.DESTINATION_ONLY) {
                            m.setJMSDestination(d);
                        } else if (headerPolicy == MessageStore.HeaderPolicy.MESSAGEID_ONLY) {
                            m.setJMSMessageID(resultSet.getString(4));
                        } else if (headerPolicy == MessageStore.HeaderPolicy.MESSAGEID_AND_DESTINATION) {
                            m.setJMSDestination(d);
                            m.setJMSMessageID(resultSet.getString(4));
                        }
                    }

                    cachedMessages.add(m);
                }

                if (cachedMessages.size() > 0) {
                    return cachedMessages.remove(0);
                } else {
                    return null;
                }
            } else {
                resultSetEmpty = true;
                close();
                return null;
            }
        }
    }

    public void close() {
        log.debug("closing MessageResultSetHandler...");

        DbUtils.closeQuietly(statement);
        DbUtils.closeQuietly(connection);

        connection = null;
    }

    public Enumeration getEnumeration() throws JMSException {
        return enumeration;
    }

    public String getMessageSelector() throws JMSException {
        return null;
    }

    public Queue getQueue() throws JMSException {
        return new MessageStoreQueue("");
    }

    public boolean hasNext() {
        return hasNextMessage();
    }

    public Message getNextMessageQuietly() {
        try {
            return getNextMessage();
        } catch (Exception ex) {
            close();

            throw new HermesRuntimeException(ex);
        }
    }
}