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Java > Open Source Codes > org > infohazard > maverick > view > DocumentView


1 /*
2  * $Id: DocumentView.java,v 1.4 2003/10/22 11:13:49 thusted Exp $
3  * $Source: /cvsroot/mav/maverick/src/java/org/infohazard/maverick/view/DocumentView.java,v $
4  */
5
6 package org.infohazard.maverick.view;
7
8 import java.io.IOException JavaDoc;
9 import java.util.Iterator JavaDoc;
10 import java.util.Map JavaDoc;
11
12 import javax.servlet.ServletException JavaDoc;
13
14 import org.apache.commons.logging.Log;
15 import org.apache.commons.logging.LogFactory;
16 import org.infohazard.maverick.flow.View;
17 import org.infohazard.maverick.flow.ViewContext;
18
19 /**
20  * <p>
21  * DocumentView is the base class for the default Maverick "document" view type.
22  * </p>
23  * <p>
24  * A DocumentView is a {@link View} that sets up a "model" object in request
25  * or session scope and forwards to another resource to render the final
26  * response.
27  * The "model" object exposes dynamic data so that it can be rendered as part
28  * of the response.
29  * </p>
30  * <p>
31  * This class is used by the Maverick {@link DocumentViewFactory}.
32  * The DocumentViewFactory defines the abstract SetAttribute method
33  * for each instance according to the parameters passed through the View XML
34  * element.
35  * </p>
36  * <p>
37  * By default, a DocumentView will be associated with a
38  * {@link DispatchedViewFactory DispatchedView} that uses the
39  * {@link javax.servlet.RequestDispatcher RequestDispatcher} to forward control
40  * to another resource (e.g. service or servlet that renders a server page).
41  * </p>
42  */
43 public abstract class DocumentView implements View
44 {
45     private static Log log = LogFactory.getLog(DocumentView.class);
46
47     /**
48      * <p>
49      * The name of the bean in the appropriate scope attributes.
50      * </p>
51      */
52     protected String JavaDoc beanName;
53
54     /**
55      * <p>
56      * Convenience constructor to pass the "model" object name and the
57      * aggregated {@link View}.
58      * </p>
59      * @param beanName The name of the bean in the appropriate scope attributes.
60      */
61     public DocumentView(String JavaDoc beanName)
62     {
63         this.beanName = beanName;
64     }
65
66     /**
67      * <p>
68      * Entry method that initiates the View rendering process.
69      * Here, the DocumentView sets the the "model" object to the appropriate
70      * scope and invokes the {@link #forward} View to complete the response.
71      * </p>
72      * @param vctx is placed in an attribute collection.
73      * @throws IOException
74      * @throws ServletException
75      * @see View#go
76      */
77     public void go(ViewContext vctx) throws IOException JavaDoc, ServletException JavaDoc
78     {
79         // Should we put the null in the collection?
80 if (vctx.getModel() != null)
81             this.setAttribute(vctx);
82
83         // Put any params in the request attributes
84 if (vctx.getViewParams() != null)
85         {
86             if (log.isDebugEnabled())
87                 log.debug("Setting " + vctx.getViewParams().size() + " params");
88
89             Iterator JavaDoc entryIt = vctx.getViewParams().entrySet().iterator();
90             while (entryIt.hasNext())
91             {
92                 Map.Entry JavaDoc entry = (Map.Entry JavaDoc)entryIt.next();
93                 vctx.getRequest().setAttribute((String JavaDoc)entry.getKey(), entry.getValue());
94             }
95         }
96         vctx.getNextStep().go("");
97     }
98
99     /**
100      * <p>
101      * Template method that can be used to place the "model" object in
102      * whatever scope is appropriate for this View element instance.
103      * </p>
104      * <p>
105      * The {@link DocumentViewFactory} provides an implementation of this
106      * method appropriate to the View parameters passed from the Maverick
107      * configuration document.
108      * </p>
109      * @param vctx provides access to request and session scope collections,
110      * if needed.
111      */
112     protected abstract void setAttribute(ViewContext vctx);
113 }
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