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Java > Open Source Codes > nextapp > echo2 > webcontainer > PartialUpdateManager


1 /*
2  * This file is part of the Echo Web Application Framework (hereinafter "Echo").
3  * Copyright (C) 2002-2005 NextApp, Inc.
4  *
5  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
6  *
7  * The contents of this file are subject to the Mozilla Public License Version
8  * 1.1 (the "License"); you may not use this file except in compliance with
9  * the License. You may obtain a copy of the License at
10  * http://www.mozilla.org/MPL/
11  *
12  * Software distributed under the License is distributed on an "AS IS" basis,
13  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
14  * for the specific language governing rights and limitations under the
15  * License.
16  *
17  * Alternatively, the contents of this file may be used under the terms of
18  * either the GNU General Public License Version 2 or later (the "GPL"), or
19  * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
20  * in which case the provisions of the GPL or the LGPL are applicable instead
21  * of those above. If you wish to allow use of your version of this file only
22  * under the terms of either the GPL or the LGPL, and not to allow others to
23  * use your version of this file under the terms of the MPL, indicate your
24  * decision by deleting the provisions above and replace them with the notice
25  * and other provisions required by the GPL or the LGPL. If you do not delete
26  * the provisions above, a recipient may use your version of this file under
27  * the terms of any one of the MPL, the GPL or the LGPL.
28  */
29
30 package nextapp.echo2.webcontainer;
31
32 import java.util.HashMap JavaDoc;
33 import java.util.Map JavaDoc;
34
35 import nextapp.echo2.app.update.ServerComponentUpdate;
36
37 /**
38  * A utility class for rendering a collection of property updates to an
39  * existing HTML representation of a component on the client browser.
40  */
41 public class PartialUpdateManager {
42     
43     /**
44      * Mapping between property names and
45      * <code>PartialUpdateParticipant</code>s.
46      */
47     private Map JavaDoc registry = null;
48
49     /**
50      * Adds a <code>PartialUpdateParticipant</code> to handle a given property.
51      *
52      * @param propertyName the name of the property
53      * @param updateParticipant the <code>PartialUpdateParticipant</code>
54      */
55     public void add(String JavaDoc propertyName, PartialUpdateParticipant updateParticipant) {
56         if (registry == null) {
57             registry = new HashMap JavaDoc();
58         }
59         registry.put(propertyName, updateParticipant);
60     }
61     
62     /**
63      * Determines if this <code>PartialUpdateManager</code> has participants
64      * to update all changed properties specified in <code>update</code>.
65      *
66      * @param rc the relevant <code>RenderContext</code>
67      * @param update the update
68      * @return true if this registry is capable of performing all the
69      * described property updates
70      */
71     public boolean canProcess(RenderContext rc, ServerComponentUpdate update) {
72         if (registry == null) {
73             return false;
74         }
75         String JavaDoc[] propertyNames = update.getUpdatedPropertyNames();
76         for (int i = 0; i < propertyNames.length; ++i) {
77             PartialUpdateParticipant propertyRender = (PartialUpdateParticipant) registry.get(propertyNames[i]);
78             if (propertyRender == null) {
79                 return false;
80             } else if (!propertyRender.canRenderProperty(rc, update)) {
81                 return false;
82             }
83         }
84         return true;
85     }
86     
87     /**
88      * Renders updates to all properties in the provided <code>update</code>.
89      * If the update contains a property for which a participant does not
90      * exist in this registry, the given property is skipped.
91      *
92      * @param rc the relevant <code>RenderContext</code>
93      * @param update the update to process
94      */
95     public void process(RenderContext rc, ServerComponentUpdate update) {
96         String JavaDoc[] propertyNames = update.getUpdatedPropertyNames();
97         for (int i = 0; i < propertyNames.length; ++i) {
98             PartialUpdateParticipant propertyRender = (PartialUpdateParticipant) registry.get(propertyNames[i]);
99             if (propertyRender == null) {
100                 // If no renderer exists, discard the property update.
101 continue;
102             }
103             propertyRender.renderProperty(rc, update);
104         }
105     }
106 }
107
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