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Java > Open Source Codes > org > apache > tapestry > listener > ListenerInvokerTerminator


1 // Copyright 2005 The Apache Software Foundation
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at
6 //
7 // http://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS,
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 // See the License for the specific language governing permissions and
13 // limitations under the License.
14
15 package org.apache.tapestry.listener;
16
17 import org.apache.hivemind.util.Defense;
18 import org.apache.tapestry.IActionListener;
19 import org.apache.tapestry.IComponent;
20 import org.apache.tapestry.IRequestCycle;
21
22 /**
23  * Terminator implementation for the tapestry.listener.InvokeListener pipeline; this is what finally
24  * turns around and invokes
25  * {@link org.apache.tapestry.IActionListener#actionTriggered(IComponent, IRequestCycle)}.
26  *
27  * @author Howard M. Lewis Ship
28  * @since 4.0
29  */
30 public class ListenerInvokerTerminator implements ListenerInvoker
31 {
32
33     /**
34      * @param listener
35      * to be invoked, may be null if no listener is found (a convienience for all the
36      * places where listeners are optional)
37      * @param source
38      * the component generating the listener "event", to be passed to the listener. Not
39      * generally used, but may not be null.
40      * @param cycle
41      * the current request cycle, to be passed to the listener.
42      * @param delegate
43      * the next invoker in the pipeline
44      */
45     public void invokeListener(IActionListener listener, IComponent source, IRequestCycle cycle)
46     {
47         Defense.notNull(source, "source");
48         Defense.notNull(cycle, "cycle");
49
50         if (listener != null)
51             listener.actionTriggered(source, cycle);
52     }
53
54 }
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