1 package org.apache.commons.jcs.engine.memory.util;
2
3 /*
4 * Licensed to the Apache Software Foundation (ASF) under one
5 * or more contributor license agreements. See the NOTICE file
6 * distributed with this work for additional information
7 * regarding copyright ownership. The ASF licenses this file
8 * to you under the Apache License, Version 2.0 (the
9 * "License"); you may not use this file except in compliance
10 * with the License. You may obtain a copy of the License at
11 *
12 * http://www.apache.org/licenses/LICENSE-2.0
13 *
14 * Unless required by applicable law or agreed to in writing,
15 * software distributed under the License is distributed on an
16 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
17 * KIND, either express or implied. See the License for the
18 * specific language governing permissions and limitations
19 * under the License.
20 */
21
22 import java.lang.ref.SoftReference;
23
24 import org.apache.commons.jcs.engine.behavior.ICacheElement;
25
26 /**
27 * This wrapper is needed for double linked lists.
28 */
29 public class SoftReferenceElementDescriptor<K, V>
30 extends MemoryElementDescriptor<K, V>
31 {
32 /** Don't change */
33 private static final long serialVersionUID = -1905161209035522460L;
34
35 /** The CacheElement wrapped by this descriptor */
36 private final SoftReference<ICacheElement<K, V>> srce;
37
38 /**
39 * Constructs a usable MemoryElementDescriptor.
40 * <p>
41 * @param ce
42 */
43 public SoftReferenceElementDescriptor( ICacheElement<K, V> ce )
44 {
45 super( null );
46 this.srce = new SoftReference<ICacheElement<K, V>>(ce);
47 }
48
49 /**
50 * @return the ce
51 */
52 @Override
53 public ICacheElement<K, V> getCacheElement()
54 {
55 if (srce != null)
56 {
57 return srce.get();
58 }
59
60 return null;
61 }
62 }