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Java > Open Source Codes > org > apache > roller > ui > rendering > filters > RequestMappingFilter


1 /*
2  * Licensed to the Apache Software Foundation (ASF) under one or more
3  * contributor license agreements. The ASF licenses this file to You
4  * under the Apache License, Version 2.0 (the "License"); you may not
5  * use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  * http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License. For additional information regarding
15  * copyright in this work, please see the NOTICE file in the top level
16  * directory of this distribution.
17  */
18
19 package org.apache.roller.ui.rendering.filters;
20
21 import java.io.IOException JavaDoc;
22 import java.util.ArrayList JavaDoc;
23 import java.util.Iterator JavaDoc;
24 import java.util.List JavaDoc;
25 import javax.servlet.Filter JavaDoc;
26 import javax.servlet.FilterChain JavaDoc;
27 import javax.servlet.FilterConfig JavaDoc;
28 import javax.servlet.ServletException JavaDoc;
29 import javax.servlet.ServletRequest JavaDoc;
30 import javax.servlet.ServletResponse JavaDoc;
31 import javax.servlet.http.HttpServletRequest JavaDoc;
32 import javax.servlet.http.HttpServletResponse JavaDoc;
33 import org.apache.commons.logging.Log;
34 import org.apache.commons.logging.LogFactory;
35 import org.apache.roller.config.RollerConfig;
36 import org.apache.roller.ui.rendering.RequestMapper;
37
38 /**
39  * Provides generalized request mapping capablilites.
40  *
41  * Incoming requests can be inspected by a series of RequestMappers and can
42  * potentially be re-routed to different places within the application.
43  *
44  * @web.filter name="RequestMappingFilter"
45  */
46 public class RequestMappingFilter implements Filter JavaDoc {
47     
48     private static Log log = LogFactory.getLog(RequestMappingFilter.class);
49     
50     // list of RequestMappers that want to inspect the request
51 private final List JavaDoc requestMappers = new ArrayList JavaDoc();
52     
53     
54     public void init(FilterConfig JavaDoc filterConfig) {
55         
56         // lookup set of request mappers we are going to use
57 String JavaDoc rollerMappers = RollerConfig.getProperty("rendering.rollerRequestMappers");
58         String JavaDoc userMappers = RollerConfig.getProperty("rendering.userRequestMappers");
59         
60         // instantiate user defined request mapper classes
61 if(userMappers != null && userMappers.trim().length() > 0) {
62             
63             RequestMapper requestMapper = null;
64             String JavaDoc[] uMappers = userMappers.split(",");
65             for(int i=0; i < uMappers.length; i++) {
66                 try {
67                     Class JavaDoc mapperClass = Class.forName(uMappers[i]);
68                     requestMapper = (RequestMapper) mapperClass.newInstance();
69                     requestMappers.add(requestMapper);
70                 } catch(ClassCastException JavaDoc cce) {
71                     log.error("It appears that your mapper does not implement "+
72                             "the RequestMapper interface", cce);
73                 } catch(Exception JavaDoc e) {
74                     log.error("Unable to instantiate request mapper ["+uMappers[i]+"]", e);
75                 }
76             }
77         }
78         
79         // instantiate roller standard request mapper classes
80 if(rollerMappers != null && rollerMappers.trim().length() > 0) {
81             
82             RequestMapper requestMapper = null;
83             String JavaDoc[] rMappers = rollerMappers.split(",");
84             for(int i=0; i < rMappers.length; i++) {
85                 try {
86                     Class JavaDoc mapperClass = Class.forName(rMappers[i]);
87                     requestMapper = (RequestMapper) mapperClass.newInstance();
88                     requestMappers.add(requestMapper);
89                 } catch(ClassCastException JavaDoc cce) {
90                     log.error("It appears that your mapper does not implement "+
91                             "the RequestMapper interface", cce);
92                 } catch(Exception JavaDoc e) {
93                     log.error("Unable to instantiate request mapper ["+rMappers[i]+"]", e);
94                 }
95             }
96         }
97         
98         if(requestMappers.size() < 1) {
99             // hmm ... failed to load any request mappers?
100 log.warn("Failed to load any request mappers. "+
101                     "Weblog urls probably won't function as you expect.");
102         }
103         
104         log.info("Request mapping filter initialized, "+requestMappers.size()+
105                 " mappers configured.");
106     }
107     
108     
109     /**
110      * Inspect incoming urls and see if they should be routed.
111      */
112     public void doFilter(ServletRequest JavaDoc req, ServletResponse JavaDoc res, FilterChain JavaDoc chain)
113             throws IOException JavaDoc, ServletException JavaDoc {
114         
115         HttpServletRequest JavaDoc request = (HttpServletRequest JavaDoc) req;
116         HttpServletResponse JavaDoc response = (HttpServletResponse JavaDoc) res;
117         
118         log.debug("entering");
119         
120         // give each mapper a chance to handle the request
121 RequestMapper mapper = null;
122         Iterator JavaDoc mappersIT = this.requestMappers.iterator();
123         while(mappersIT.hasNext()) {
124             mapper = (RequestMapper) mappersIT.next();
125             
126             log.debug("trying mapper "+mapper.getClass().getName());
127             
128             boolean wasHandled = mapper.handleRequest(request, response);
129             if(wasHandled) {
130                 // if mapper has handled the request then we are done
131 log.debug("request handled by "+mapper.getClass().getName());
132                 log.debug("exiting");
133                 return;
134             }
135         }
136         
137         log.debug("request not mapped");
138         
139         // nobody handled the request, so let it continue as usual
140 chain.doFilter(request, response);
141         
142         log.debug("exiting");
143     }
144     
145     
146     public void destroy() {}
147     
148 }
149
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