Source code

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 */
017package org.apache.wicket.protocol.http.servlet;
018
019import java.io.IOException;
020
021import javax.servlet.Filter;
022import javax.servlet.FilterChain;
023import javax.servlet.FilterConfig;
024import javax.servlet.ServletException;
025import javax.servlet.ServletRequest;
026import javax.servlet.ServletResponse;
027import javax.servlet.http.HttpServletRequest;
028import javax.servlet.http.HttpSession;
029
030import org.apache.wicket.Application;
031import org.apache.wicket.Session;
032import org.apache.wicket.ThreadContext;
033import org.apache.wicket.protocol.http.WebApplication;
034import org.apache.wicket.protocol.http.WicketFilter;
035import org.slf4j.Logger;
036import org.slf4j.LoggerFactory;
037
038/**
039 * This filter can be used to make the Wicket {@link org.apache.wicket.protocol.http.WebSession}
040 * instances available to non-wicket servlets.
041 * <p>
042 * The following example shows how this filter is setup to for a servlet. You can find the example
043 * in the wicket-examples project.
044 * 
045 * <pre>
046 *  &lt;!-- The WicketSesionFilter can be used to provide thread local access to servlets/ JSPs/ etc --&gt;
047 *  &lt;filter&gt;
048 *    &lt;filter-name&gt;WicketSessionFilter&lt;/filter-name&gt;
049 *    &lt;filter-class&gt;org.apache.wicket.protocol.http.servlet.WicketSessionFilter&lt;/filter-class&gt;
050 *    &lt;init-param&gt;
051 *      &lt;param-name&gt;filterName&lt;/param-name&gt;
052 *      &lt;!-- expose the session of the input example app --&gt;
053 *      &lt;param-value&gt;FormInputApplication&lt;/param-value&gt;
054 *    &lt;/init-param&gt;
055 *  &lt;/filter&gt;
056 * 
057 *  &lt;!-- couple the session filter to the helloworld servlet --&gt;
058 *  &lt;filter-mapping&gt;
059 *    &lt;filter-name&gt;WicketSessionFilter&lt;/filter-name&gt;
060 *    &lt;url-pattern&gt;/helloworldservlet/*&lt;/url-pattern&gt;
061 *  &lt;/filter-mapping&gt;
062 *  ...
063 * 
064 *  &lt;servlet&gt;
065 *    &lt;servlet-name&gt;HelloWorldServlet&lt;/servlet-name&gt;
066 *    &lt;servlet-class&gt;org.apache.wicket.examples.HelloWorldServlet&lt;/servlet-class&gt;
067 *  &lt;/servlet&gt;
068 * 
069 *  &lt;servlet-mapping&gt;
070 *    &lt;servlet-name&gt;HelloWorldServlet&lt;/servlet-name&gt;
071 *    &lt;url-pattern&gt;/helloworldservlet/*&lt;/url-pattern&gt;
072 *  &lt;/servlet-mapping&gt;
073 * </pre>
074 * 
075 * Note: If both {@link WicketFilter} and {@link WicketSessionFilter} are mapped to the same url
076 * pattern, make sure to have the {@code <filter-mapping>} for {@link WicketFilter} first in your
077 * {@code web.xml}.
078 * <p>
079 * After that, you can get to the Wicket session in the usual fashion:
080 * 
081 * <pre>
082 * if (Session.exists())
083 * {
084 *      Session wicketSession = Session.get();
085 * }
086 * </pre>
087 * 
088 * Make sure to test for session existence first, like the HelloWorldServlet does:
089 * 
090 * <pre>
091 * public class HelloWorldServlet extends HttpServlet
092 * {
093 *      public void doGet(HttpServletRequest req, HttpServletResponse res) throws ServletException,
094 *              IOException
095 *      {
096 *              res.setContentType(&quot;text/html&quot;);
097 *              PrintWriter out = res.getWriter();
098 *              String message = &quot;Hi. &quot; +
099 *                      (Session.exists() ? &quot; I know Wicket session &quot; + Session.get() + &quot;.&quot;
100 *                              : &quot; I can't find a Wicket session.&quot;);
101 *              out.println(message);
102 *              out.close();
103 *      }
104 * }
105 * </pre>
106 * 
107 * @author Eelco Hillenius
108 */
109public class WicketSessionFilter implements Filter
110{
111        /** log. */
112        private static final Logger logger = LoggerFactory.getLogger(WicketSessionFilter.class);
113
114        /** the filter name/ application key. */
115        private String filterName;
116
117        /** the session key where the Wicket session should be stored. */
118        private String sessionKey;
119
120        /**
121         * Construct.
122         */
123        public WicketSessionFilter()
124        {
125        }
126
127        /**
128         * @see javax.servlet.Filter#init(javax.servlet.FilterConfig)
129         */
130        @Override
131        public void init(FilterConfig filterConfig) throws ServletException
132        {
133                filterName = filterConfig.getInitParameter("filterName");
134
135                if (filterName == null)
136                {
137                        throw new ServletException(
138                                "you must provide init parameter 'filterName if you want to use " +
139                                        getClass().getName());
140                }
141
142                logger.debug("filterName/application key set to {}", filterName);
143        }
144
145        /**
146         * @see javax.servlet.Filter#doFilter(javax.servlet.ServletRequest,
147         *      javax.servlet.ServletResponse, javax.servlet.FilterChain)
148         */
149        @Override
150        public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
151                throws IOException, ServletException
152        {
153                try
154                {
155                        WebApplication application = bindApplication();
156                        bindSession(request, application);
157                        chain.doFilter(request, response);
158                }
159                finally
160                {
161                        cleanupBoundApplicationAndSession();
162                }
163        }
164
165        private void cleanupBoundApplicationAndSession()
166        {
167                ThreadContext.detach();
168        }
169
170        private void bindSession(ServletRequest request, WebApplication application)
171        {
172                // find wicket session and bind it to thread
173
174                HttpSession httpSession = ((HttpServletRequest)request).getSession(false);
175                Session session = getSession(httpSession, application);
176                if (session == null)
177                {
178                        if (logger.isDebugEnabled())
179                        {
180                                logger.debug("could not set Wicket session: key " + sessionKey +
181                                        " not found in http session for " +
182                                        ((HttpServletRequest)request).getContextPath() + "," + request.getServerName() +
183                                        ", or http session does not exist");
184                        }
185                }
186                else
187                {
188                        ThreadContext.setSession(session);
189                }
190        }
191
192        private WebApplication bindApplication()
193        {
194                // find wicket application and bind it to thread
195
196                WebApplication application = (WebApplication)Application.get(filterName);
197                if (application == null)
198                {
199                        throw new IllegalStateException("Could not find wicket application mapped to filter: " +
200                                filterName +
201                                ". Make sure you set filterName attribute to the name of the wicket filter " +
202                                "for the wicket application whose session you want to access.");
203                }
204                ThreadContext.setApplication(application);
205                return application;
206        }
207
208        private Session getSession(HttpSession session, WebApplication application)
209        {
210                if (session != null)
211                {
212                        if (sessionKey == null)
213                        {
214                                sessionKey = application.getSessionAttributePrefix(null, filterName) +
215                                        Session.SESSION_ATTRIBUTE_NAME;
216
217                                logger.debug("will use {} as the session key to get the Wicket session", sessionKey);
218                        }
219
220                        return (Session)session.getAttribute(sessionKey);
221                }
222                return null;
223        }
224
225        /**
226         * @see javax.servlet.Filter#destroy()
227         */
228        @Override
229        public void destroy()
230        {
231        }
232}