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ActiveMQ example source code file (AjaxServlet.java)

This example ActiveMQ source code file (AjaxServlet.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

ajaxservlet, bytearrayoutputstream, bytearrayoutputstream, http, httpservletresponse, if-modified-since, io, ioexception, ioexception, last-modified, map, messagelistenerservlet, request, response, servlet, servletexception, servletexception, string, string, util

The ActiveMQ AjaxServlet.java source code

//========================================================================
//Copyright 2006 Mort Bay Consulting Pty. Ltd.
//------------------------------------------------------------------------
//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.apache.activemq.web;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.util.HashMap;
import java.util.Map;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/* ------------------------------------------------------------ */
/**
 * AjaxServlet. The AjaxServlet extends the {@link MessageListenerServlet} with
 * the capability to server the <code>amq.js script and associated
 * scripts from resources within the activemq-web jar. The amq.js script is the
 * client side companion to the MessageListenerServlet and supports sending
 * messages and long polling for receiving messages (Also called Comet style
 * Ajax).
 */
public class AjaxServlet extends MessageListenerServlet {

    private static final long serialVersionUID = -3875280764356406114L;
    private Map<String, byte[]> jsCache = new HashMap();
    private long jsLastModified = 1000 * (System.currentTimeMillis() / 1000);

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        if (request.getPathInfo() != null && request.getPathInfo().endsWith(".js")) {
            doJavaScript(request, response);
        } else {
            super.doGet(request, response);
        }
    }

    protected void doJavaScript(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException {

        // Look for a local resource first.
        String js = request.getServletPath() + request.getPathInfo();
        URL url = getServletContext().getResource(js);
        if (url != null) {
            getServletContext().getNamedDispatcher("default").forward(request, response);
            return;
        }

        // Serve from the classpath resources
        String resource = "org/apache/activemq/web" + request.getPathInfo();
        synchronized (jsCache) {

            byte[] data = jsCache.get(resource);
            if (data == null) {
                InputStream in = Thread.currentThread().getContextClassLoader().getResourceAsStream(resource);
                if (in != null) {
                    ByteArrayOutputStream out = new ByteArrayOutputStream();
                    byte[] buf = new byte[4096];
                    int len = in.read(buf);
                    while (len >= 0) {
                        out.write(buf, 0, len);
                        len = in.read(buf);
                    }
                    in.close();
                    out.close();
                    data = out.toByteArray();
                    jsCache.put(resource, data);
                }
            }

            if (data != null) {

                long ifModified = request.getDateHeader("If-Modified-Since");

                if (ifModified == jsLastModified) {
                    response.sendError(HttpServletResponse.SC_NOT_MODIFIED);
                } else {
                    response.setContentType("application/x-javascript");
                    response.setContentLength(data.length);
                    response.setDateHeader("Last-Modified", jsLastModified);
                    response.getOutputStream().write(data);
                }
            } else {
                response.sendError(HttpServletResponse.SC_NOT_FOUND);
            }
        }
    }
}

Other ActiveMQ examples (source code examples)

Here is a short list of links related to this ActiveMQ AjaxServlet.java source code file:

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