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Java > Open Source Codes > org > displaytag > filter > DisplayTagSpringInterceptor


1 /**
2  * Licensed under the Artistic License; you may not use this file
3  * except in compliance with the License.
4  * You may obtain a copy of the License at
5  *
6  * http://displaytag.sourceforge.net/license.html
7  *
8  * THIS PACKAGE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR
9  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
10  * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
11  */
12 package org.displaytag.filter;
13
14 import java.util.HashMap JavaDoc;
15 import java.util.Map JavaDoc;
16
17 import javax.servlet.http.HttpServletRequest JavaDoc;
18 import javax.servlet.http.HttpServletResponse JavaDoc;
19
20 import org.apache.commons.logging.Log;
21 import org.apache.commons.logging.LogFactory;
22 import org.displaytag.Messages;
23 import org.displaytag.tags.TableTag;
24 import org.displaytag.tags.TableTagParameters;
25 import org.springframework.web.servlet.HandlerAdapter;
26 import org.springframework.web.servlet.HandlerInterceptor;
27 import org.springframework.web.servlet.ModelAndView;
28 import org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter;
29
30
31 /**
32  * <p>
33  * Allow the author of an included JSP page to reset the content type to something else (like a binary stream), and then
34  * write the new info back as the exclusive response, clearing the buffers of all previously added content.
35  * </p>
36  * <p>
37  * This interceptor allows TableTag users to perform exports from pages that are run as includes, such as from Struts or
38  * a jsp:include. If that is your intention, just add this interceptor to your spring dispatcher context xml and map it
39  * to the appropriate requests, using something like:
40  * </p>
41  *
42  * <pre>
43  * &lt;bean id="urlMapping" class="org.springframework.web.servlet.handler.SimpleUrlHandlerMapping">
44  * &lt;property name="interceptors">
45  * &lt;list>
46  * &lt;bean class="org.displaytag.filter.DisplayTagSpringInterceptor"/>
47  * &lt;/list>
48  * &lt;/property
49  * &lt;/bean>
50  * </pre>
51  *
52  * <p>
53  * By default the interceptor buffers all the export content before writing it out. You can set an optional parameter
54  * <code>buffer</code> to <code>false</code> to make the interceptor write directly to the output stream. This could
55  * be faster and uses less memory, but the content length will not be set.
56  * </p>
57  *
58  * <pre>
59  * &lt;bean class="org.displaytag.filter.DisplayTagSpringInterceptor">
60  * &lt;property name="buffer">&lt;value>false&lt;/value>&lt;/property>
61  * &lt;/bean>
62  * </pre>
63  *
64  * @author Keith Garry Boyce
65  * @author rapruitt
66  * @author Fabrizio Giustina
67  * @version $Revision: 907 $ ($Author: fgiust $)
68  */
69 public class DisplayTagSpringInterceptor implements HandlerInterceptor
70 {
71
72     /**
73      * Logger.
74      */
75     static Log log = LogFactory.getLog(DisplayTagSpringInterceptor.class);
76
77     /**
78      * Force response buffering. Enabled by default.
79      */
80     private boolean buffer = true;
81
82     /**
83      * Sets the buffer state.
84      * @param bufferingEnabled it <code>true</code> buffering will be used
85      */
86     public void setBuffer(boolean bufferingEnabled)
87     {
88         this.buffer = bufferingEnabled;
89     }
90
91     /**
92      * @see HandlerInterceptor#preHandle(HttpServletRequest,HttpServletResponse, Object)
93      */
94     public boolean preHandle(HttpServletRequest JavaDoc request, HttpServletResponse JavaDoc response, Object JavaDoc handler) throws Exception JavaDoc
95     {
96
97         if (request.getParameter(TableTagParameters.PARAMETER_EXPORTING) == null)
98         {
99             if (log.isDebugEnabled())
100             {
101                 log.debug(Messages.getString("ResponseOverrideFilter.parameternotfound")); //$NON-NLS-1$
102 }
103             // don't intercept!
104 return true;
105         }
106
107         BufferedResponseWrapper wrapper = new BufferedResponseWrapper13Impl(response);
108
109         Map JavaDoc contentBean = new HashMap JavaDoc(4);
110         if (buffer)
111         {
112             contentBean.put(TableTagParameters.BEAN_BUFFER, Boolean.TRUE);
113         }
114         request.setAttribute(TableTag.FILTER_CONTENT_OVERRIDE_BODY, contentBean);
115
116         if (log.isDebugEnabled())
117         {
118             log.debug("handler is " + handler);
119         }
120
121         HandlerAdapter handlerAdaptor = new SimpleControllerHandlerAdapter();
122         handlerAdaptor.handle(request, wrapper, handler);
123
124         ExportDelegate.writeExport(response, request, wrapper);
125
126         return false;
127     }
128
129     /**
130      * @see HandlerInterceptor#postHandle(HttpServletRequest,HttpServletResponse, Object, ModelAndView)
131      */
132     public void postHandle(HttpServletRequest JavaDoc request, HttpServletResponse JavaDoc response, Object JavaDoc obj,
133         ModelAndView modelAndView) throws Exception JavaDoc
134     {
135         // Nothing to do
136 }
137
138     /**
139      * @see HandlerInterceptor#afterCompletion(HttpServletRequest,HttpServletResponse, Object, Exception)
140      */
141     public void afterCompletion(HttpServletRequest JavaDoc request, HttpServletResponse JavaDoc response, Object JavaDoc obj,
142         Exception JavaDoc exception) throws Exception JavaDoc
143     {
144         // Nothing to do
145 }
146
147 }
148
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