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Java > Open Source Codes > org > springframework > webflow > conversation > impl > NoOpConversationLock


1 /*
2  * Copyright 2002-2006 the original author or authors.
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  * http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 package org.springframework.webflow.conversation.impl;
17
18 import java.io.ObjectStreamException JavaDoc;
19 import java.io.Serializable JavaDoc;
20
21 /**
22  * A singleton lock that doesn't do anything. For use when conversations don't
23  * require or choose not to implement locking.
24  *
25  * @author Keith Donald
26  */
27 class NoOpConversationLock implements ConversationLock, Serializable JavaDoc {
28
29     /**
30      * The singleton instance.
31      */
32     public static final NoOpConversationLock INSTANCE = new NoOpConversationLock();
33
34     /**
35      * Private constructor to avoid instantiation.
36      */
37     private NoOpConversationLock() {
38     }
39
40     public void lock() {
41         // no-op
42 }
43
44     public void unlock() {
45         // no-op
46 }
47
48     // resolve the singleton instance
49 private Object JavaDoc readResolve() throws ObjectStreamException JavaDoc {
50         return INSTANCE;
51     }
52 }
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