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Java > Open Source Codes > org > springframework > web > context > request > RequestContextListener


1 /*
2  * Copyright 2002-2007 the original author or authors.
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not 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.
15  */
16
17 package org.springframework.web.context.request;
18
19 import javax.servlet.ServletRequestEvent JavaDoc;
20 import javax.servlet.ServletRequestListener JavaDoc;
21 import javax.servlet.http.HttpServletRequest JavaDoc;
22
23 import org.apache.commons.logging.Log;
24 import org.apache.commons.logging.LogFactory;
25
26 import org.springframework.context.i18n.LocaleContextHolder;
27
28 /**
29  * Servlet 2.4+ listener that exposes the request to the current thread,
30  * through both {@link org.springframework.context.i18n.LocaleContextHolder} and
31  * {@link RequestContextHolder}. To be registered as listener in <code>web.xml</code>.
32  *
33  * <p>Alternatively, Spring's {@link org.springframework.web.filter.RequestContextFilter}
34  * and Spring's {@link org.springframework.web.servlet.DispatcherServlet} also expose
35  * the same request context to the current thread.
36  *
37  * <p>This listener is mainly for use with third-party servlets, e.g. the JSF FacesServlet.
38  * Within Spring's own web support, DispatcherServlet's processing is perfectly sufficient.
39  *
40  * @author Juergen Hoeller
41  * @author Steven Devijver
42  * @since 2.0
43  * @see javax.servlet.ServletRequestListener
44  * @see org.springframework.context.i18n.LocaleContextHolder
45  * @see org.springframework.web.context.request.RequestContextHolder
46  * @see org.springframework.web.filter.RequestContextFilter
47  * @see org.springframework.web.servlet.DispatcherServlet
48  */
49 public class RequestContextListener implements ServletRequestListener JavaDoc {
50
51     private static final String JavaDoc REQUEST_ATTRIBUTES_ATTRIBUTE =
52             RequestContextListener.class.getName() + ".REQUEST_ATTRIBUTES";
53
54     /** Logger available to subclasses */
55     protected final Log logger = LogFactory.getLog(getClass());
56
57
58     public void requestInitialized(ServletRequestEvent JavaDoc requestEvent) {
59         if (!(requestEvent.getServletRequest() instanceof HttpServletRequest JavaDoc)) {
60             throw new IllegalArgumentException JavaDoc(
61                     "Request is not an HttpServletRequest: " + requestEvent.getServletRequest());
62         }
63         HttpServletRequest JavaDoc request = (HttpServletRequest JavaDoc) requestEvent.getServletRequest();
64         ServletRequestAttributes attributes = new ServletRequestAttributes(request);
65         request.setAttribute(REQUEST_ATTRIBUTES_ATTRIBUTE, attributes);
66         LocaleContextHolder.setLocale(request.getLocale());
67         RequestContextHolder.setRequestAttributes(attributes);
68         if (logger.isDebugEnabled()) {
69             logger.debug("Bound request context to thread: " + request);
70         }
71     }
72
73     public void requestDestroyed(ServletRequestEvent JavaDoc requestEvent) {
74         ServletRequestAttributes attributes =
75                 (ServletRequestAttributes) requestEvent.getServletRequest().getAttribute(REQUEST_ATTRIBUTES_ATTRIBUTE);
76         ServletRequestAttributes threadAttributes =
77                 (ServletRequestAttributes) RequestContextHolder.getRequestAttributes();
78         if (threadAttributes != null) {
79             // We're assumably within the original request thread...
80 if (attributes == null) {
81                 attributes = threadAttributes;
82             }
83             RequestContextHolder.setRequestAttributes(null);
84             LocaleContextHolder.setLocale(null);
85         }
86         if (attributes != null) {
87             attributes.requestCompleted();
88             if (logger.isDebugEnabled()) {
89                 logger.debug("Cleared thread-bound request context: " + requestEvent.getServletRequest());
90             }
91         }
92     }
93
94 }
95
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