001    //========================================================================
002    //Copyright 2006 Mort Bay Consulting Pty. Ltd.
003    //------------------------------------------------------------------------
004    //Licensed under the Apache License, Version 2.0 (the "License");
005    //you may not use this file except in compliance with the License.
006    //You may obtain a copy of the License at 
007    //http://www.apache.org/licenses/LICENSE-2.0
008    //Unless required by applicable law or agreed to in writing, software
009    //distributed under the License is distributed on an "AS IS" BASIS,
010    //WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
011    //See the License for the specific language governing permissions and
012    //limitations under the License.
013    //========================================================================
014    
015    package org.apache.activemq.web;
016    
017    import java.io.ByteArrayOutputStream;
018    import java.io.IOException;
019    import java.io.InputStream;
020    import java.net.URL;
021    import java.util.HashMap;
022    import java.util.Map;
023    
024    import javax.servlet.ServletException;
025    import javax.servlet.http.HttpServletRequest;
026    import javax.servlet.http.HttpServletResponse;
027    
028    /* ------------------------------------------------------------ */
029    /**
030     * AjaxServlet. The AjaxServlet extends the {@link MessageListenerServlet} with
031     * the capability to server the <code>amq.js</code> script and associated
032     * scripts from resources within the activemq-web jar. The amq.js script is the
033     * client side companion to the MessageListenerServlet and supports sending
034     * messages and long polling for receiving messages (Also called Comet style
035     * Ajax).
036     */
037    public class AjaxServlet extends MessageListenerServlet {
038    
039        private static final long serialVersionUID = -3875280764356406114L;
040        private Map<String, byte[]> jsCache = new HashMap<String, byte[]>();
041        private long jsLastModified = 1000 * (System.currentTimeMillis() / 1000);
042    
043        protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
044            if (request.getPathInfo() != null && request.getPathInfo().endsWith(".js")) {
045                doJavaScript(request, response);
046            } else {
047                super.doGet(request, response);
048            }
049        }
050    
051        protected void doJavaScript(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException {
052    
053            // Look for a local resource first.
054            String js = request.getServletPath() + request.getPathInfo();
055            URL url = getServletContext().getResource(js);
056            if (url != null) {
057                getServletContext().getNamedDispatcher("default").forward(request, response);
058                return;
059            }
060    
061            // Serve from the classpath resources
062            String resource = "org/apache/activemq/web" + request.getPathInfo();
063            synchronized (jsCache) {
064    
065                byte[] data = jsCache.get(resource);
066                if (data == null) {
067                    InputStream in = Thread.currentThread().getContextClassLoader().getResourceAsStream(resource);
068                    if (in != null) {
069                        ByteArrayOutputStream out = new ByteArrayOutputStream();
070                        byte[] buf = new byte[4096];
071                        int len = in.read(buf);
072                        while (len >= 0) {
073                            out.write(buf, 0, len);
074                            len = in.read(buf);
075                        }
076                        in.close();
077                        out.close();
078                        data = out.toByteArray();
079                        jsCache.put(resource, data);
080                    }
081                }
082    
083                if (data != null) {
084    
085                    long ifModified = request.getDateHeader("If-Modified-Since");
086    
087                    if (ifModified == jsLastModified) {
088                        response.sendError(HttpServletResponse.SC_NOT_MODIFIED);
089                    } else {
090                        response.setContentType("application/x-javascript");
091                        response.setContentLength(data.length);
092                        response.setDateHeader("Last-Modified", jsLastModified);
093                        response.getOutputStream().write(data);
094                    }
095                } else {
096                    response.sendError(HttpServletResponse.SC_NOT_FOUND);
097                }
098            }
099        }
100    }