001    // Copyright 2004, 2005 The Apache Software Foundation
002    //
003    // Licensed under the Apache License, Version 2.0 (the "License");
004    // you may not use this file except in compliance with the License.
005    // You may obtain a copy of the License at
006    //
007    //     http://www.apache.org/licenses/LICENSE-2.0
008    //
009    // Unless required by applicable law or agreed to in writing, software
010    // distributed under the License is distributed on an "AS IS" BASIS,
011    // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012    // See the License for the specific language governing permissions and
013    // limitations under the License.
014    
015    package org.apache.tapestry.engine;
016    
017    import java.io.IOException;
018    import java.util.HashMap;
019    import java.util.Map;
020    
021    import javax.servlet.http.HttpServletRequest;
022    import javax.servlet.http.HttpServletResponse;
023    import javax.servlet.http.HttpSession;
024    
025    import org.apache.commons.logging.Log;
026    import org.apache.tapestry.IRequestCycle;
027    import org.apache.tapestry.Tapestry;
028    import org.apache.tapestry.services.AbsoluteURLBuilder;
029    import org.apache.tapestry.services.LinkFactory;
030    import org.apache.tapestry.services.ServiceConstants;
031    
032    /**
033     * Restarts the Tapestry application. This is normally reserved for dealing with catastrophic
034     * failures of the application. Discards the {@link javax.servlet.http.HttpSession}, if any, and
035     * redirects to the Tapestry application servlet URL (invoking the {@link HomeService}).
036     * 
037     * @author Howard Lewis Ship
038     * @since 1.0.9
039     */
040    
041    public class RestartService implements IEngineService
042    {
043        /** @since 4.0 */
044        private Log _log;
045    
046        /** @since 4.0 */
047        private HttpServletRequest _request;
048    
049        /** @since 4.0 */
050        private HttpServletResponse _response;
051    
052        /** @since 4.0 */
053        private LinkFactory _linkFactory;
054    
055        /** @since 4.0 */
056        private String _servletPath;
057    
058        public ILink getLink(boolean post, Object parameter)
059        {
060            if (parameter != null)
061                throw new IllegalArgumentException(EngineMessages.serviceNoParameter(this));
062    
063            Map parameters = new HashMap();
064    
065            return _linkFactory.constructLink(this, post, parameters, true);
066        }
067    
068        public void service(IRequestCycle cycle) throws IOException
069        {
070            HttpSession session = _request.getSession(false);
071    
072            if (session != null)
073            {
074                try
075                {
076                    session.invalidate();
077                }
078                catch (IllegalStateException ex)
079                {
080                    _log.warn("Exception thrown invalidating HttpSession.", ex);
081    
082                    // Otherwise, ignore it.
083                }
084            }
085    
086            String url = cycle.getAbsoluteURL(_servletPath);
087    
088            _response.sendRedirect(url);
089        }
090    
091        public String getName()
092        {
093            return Tapestry.RESTART_SERVICE;
094        }
095    
096        /** @since 4.0 */
097        public void setLog(Log log)
098        {
099            _log = log;
100        }
101    
102        /** @since 4.0 */
103        public void setRequest(HttpServletRequest request)
104        {
105            _request = request;
106        }
107    
108        /** @since 4.0 */
109        public void setResponse(HttpServletResponse response)
110        {
111            _response = response;
112        }
113    
114        /** @since 4.0 */
115        public void setLinkFactory(LinkFactory linkFactory)
116        {
117            _linkFactory = linkFactory;
118        }
119    
120        /** @since 4.0 */
121        public void setServletPath(String servletPath)
122        {
123            _servletPath = servletPath;
124        }
125    }