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Java > Open Source Codes > nextapp > echo2 > webrender > servermessage > EventProcessor


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.webrender.servermessage;
31
32 import nextapp.echo2.webrender.ServerMessage;
33
34 import org.w3c.dom.Element JavaDoc;
35
36 /**
37  * A utility class to add <code>EchoEventProcessor</code> message parts to the
38  * <code>ServerMessage</code>. <code>EchoEventProcessor</code> message parts
39  * are used to register/unregister client-side event listeners.
40  */
41 public class EventProcessor {
42
43     private static final String JavaDoc MESSAGE_PART_NAME = "EchoEventProcessor.MessageProcessor";
44     private static final String JavaDoc[] EVENT_ADD_KEYS = new String JavaDoc[]{"type", "handler"};
45     private static final String JavaDoc[] EVENT_REMOVE_KEYS = new String JavaDoc[]{"type"};
46     
47     /**
48      * Creates an <code>event-add</code> operation to register a client event
49      * listener of a particular type on an HTML element.
50      *
51      * @param serverMessage the outgoing <code>ServerMessage</code>
52      * @param eventType the type of event (the "on" prefix should be
53      * omitted, e.g., "onmousedown" would be expressed as
54      * "mousedown")
55      * @param elementId the id of the listened-to DOM element
56      * @param eventHandler the name of the handler method to be invoked
57      * when the event occurs, e.g., "EchoButton.processAction"
58      */
59     public static void renderEventAdd(ServerMessage serverMessage, String JavaDoc eventType,
60             String JavaDoc elementId, String JavaDoc eventHandler) {
61         Element JavaDoc itemizedUpdateElement = serverMessage.getItemizedDirective(ServerMessage.GROUP_ID_POSTUPDATE,
62                 MESSAGE_PART_NAME, "event-add", EVENT_ADD_KEYS, new String JavaDoc[]{eventType, eventHandler});
63         Element JavaDoc itemElement = serverMessage.getDocument().createElement("item");
64         itemElement.setAttribute("eid", elementId);
65         itemizedUpdateElement.appendChild(itemElement);
66     }
67     
68     /**
69      * Creates an <code>event-remove</code> operation to unregister a client
70      * event listener of a particular type on an HTML element.
71      *
72      * @param serverMessage the outgoing <code>ServerMessage</code>
73      * @param eventType the type of event (the "on" prefix should be
74      * omitted, e.g., "onmousedown" would be expressed as
75      * "mousedown")
76      * @param elementId the id of the listened-to DOM element
77      */
78     public static void renderEventRemove(ServerMessage serverMessage, String JavaDoc eventType,
79             String JavaDoc elementId) {
80         Element JavaDoc itemizedUpdateElement = serverMessage.getItemizedDirective(ServerMessage.GROUP_ID_PREREMOVE,
81                 MESSAGE_PART_NAME, "event-remove", EVENT_REMOVE_KEYS, new String JavaDoc[]{eventType});
82         Element JavaDoc itemElement = serverMessage.getDocument().createElement("item");
83         itemElement.setAttribute("eid", elementId);
84         itemizedUpdateElement.appendChild(itemElement);
85     }
86 }
87
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