1   /**
2    * Copyright (c) 2000-2010 Liferay, Inc. All rights reserved.
3    *
4    * The contents of this file are subject to the terms of the Liferay Enterprise
5    * Subscription License ("License"). You may not use this file except in
6    * compliance with the License. You can obtain a copy of the License by
7    * contacting Liferay, Inc. See the License for the specific language governing
8    * permissions and limitations under the License, including but not limited to
9    * distribution rights of the Software.
10   *
11   *
12   *
13   */
14  
15  package com.liferay.portal.kernel.memory;
16  
17  import java.lang.ref.SoftReference;
18  
19  /**
20   * <a href="SoftReferenceThreadLocal.java.html"><b><i>View Source</i></b></a>
21   *
22   * @author Shuyang Zhou
23   */
24  public class SoftReferenceThreadLocal<T> extends ThreadLocal<T> {
25  
26      public T get() {
27          SoftReference<T> softReference = _softReferenceThreadLocal.get();
28  
29          if (softReference == _nullSoftReference) {
30              return null;
31          }
32  
33          T value = null;
34  
35          if (softReference != null) {
36              value = softReference.get();
37          }
38  
39          if (value == null) {
40              value = initialValue();
41  
42              set(value);
43          }
44  
45          return value;
46      }
47  
48      public void remove() {
49          _softReferenceThreadLocal.remove();
50      }
51  
52      public void set(T value) {
53          if (value == null) {
54              _softReferenceThreadLocal.set((SoftReference<T>)_nullSoftReference);
55          }
56          else {
57              _softReferenceThreadLocal.set(new SoftReference<T>(value));
58          }
59      }
60  
61      private static SoftReference<Object> _nullSoftReference =
62          new SoftReference<Object>(null);
63  
64      private ThreadLocal<SoftReference<T>> _softReferenceThreadLocal =
65          new ThreadLocal<SoftReference<T>>();
66  
67  }