ActiveMQ example source code file (QueueBrowseServlet.java)

This example ActiveMQ source code file (QueueBrowseServlet.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 - ActiveMQ tags/keywords

factoryfinder, http, io, ioexception, jmsexception, message, messagerenderer, messagerenderer, nosuchviewstyleexception, nosuchviewstyleexception, request, response, servlet, servletexception, servletexception, session, string, string, util, xmlmessagerenderer

The ActiveMQ QueueBrowseServlet.java source code

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF 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
 *
 *      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.apache.activemq.web;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Map;

import javax.jms.JMSException;
import javax.jms.Message;
import javax.jms.Queue;
import javax.jms.QueueBrowser;
import javax.jms.Session;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.activemq.util.FactoryFinder;
import org.apache.activemq.util.IntrospectionSupport;
import org.apache.activemq.web.view.MessageRenderer;
import org.apache.activemq.web.view.XmlMessageRenderer;

/**
 * Renders the contents of a queue using some kind of view. The URI is assumed
 * to be the queue. The following parameters can be used
 * <p/>
 * <ul>
 * <li>view - specifies the type of the view such as simple, xml, rss
 * <li>selector - specifies the SQL 92 selector to apply to the queue
 * </ul>
 *
 * 
 */
public class QueueBrowseServlet extends HttpServlet {
    private static FactoryFinder factoryFinder = new FactoryFinder("META-INF/services/org/apache/activemq/web/view/");

    // Implementation methods
    // -------------------------------------------------------------------------
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        try {
            WebClient client = WebClient.getWebClient(request);
            Session session = client.getSession();
            Queue queue = getQueue(request, session);
            if (queue == null) {
                throw new ServletException("No queue URI specified");
            }

            String msgId = request.getParameter("msgId");
            if (msgId == null) {
                MessageRenderer renderer = getMessageRenderer(request);
                configureRenderer(request, renderer);

                String selector = getSelector(request);
                QueueBrowser browser = session.createBrowser(queue, selector);
                renderer.renderMessages(request, response, browser);
            }
            else {
                XmlMessageRenderer renderer = new XmlMessageRenderer();
                QueueBrowser browser = session.createBrowser(queue, "JMSMessageID='" + msgId + "'");
                if (!browser.getEnumeration().hasMoreElements()) {
                    response.sendError(HttpServletResponse.SC_NOT_FOUND);
                    return;
                }
                Message message = (Message) browser.getEnumeration().nextElement();

                PrintWriter writer = response.getWriter();
                renderer.renderMessage(writer, request, response, browser, message);
                writer.flush();
            }
        }
        catch (JMSException e) {
            throw new ServletException(e);
        }
    }

    protected MessageRenderer getMessageRenderer(HttpServletRequest request) throws IOException, ServletException {
        String style = request.getParameter("view");
        if (style == null) {
            style = "simple";
        }
        try {
            return (MessageRenderer) factoryFinder.newInstance(style);
        }
        catch (IllegalAccessException e) {
            throw new NoSuchViewStyleException(style, e);
        }
        catch (InstantiationException e) {
            throw new NoSuchViewStyleException(style, e);
        }
        catch (ClassNotFoundException e) {
            throw new NoSuchViewStyleException(style, e);
        }
    }

    @SuppressWarnings("unchecked")
    protected void configureRenderer(HttpServletRequest request, MessageRenderer renderer) {
        Map<String, String> properties = new HashMap();
        for (Enumeration<String> iter = request.getParameterNames(); iter.hasMoreElements();) {
            String name = (String) iter.nextElement();
            properties.put(name, request.getParameter(name));
        }
        IntrospectionSupport.setProperties(renderer, properties);
    }

    protected String getSelector(HttpServletRequest request) {
        return request.getParameter("selector");
    }

    protected Queue getQueue(HttpServletRequest request, Session session) throws JMSException {
        String uri = request.getPathInfo();
        if (uri == null) {
            return null;
        }

        // replace URI separator with JMS destination separator
        if (uri.startsWith("/")) {
            uri = uri.substring(1);
            if (uri.length() == 0) {
                return null;
            }
        }
        uri = uri.replace('/', '.');

        return session.createQueue(uri);
    }
}