001: /*
002: * ====================================================================
003: * JAFFA - Java Application Framework For All
004: *
005: * Copyright (C) 2002 JAFFA Development Group
006: *
007: * This library is free software; you can redistribute it and/or
008: * modify it under the terms of the GNU Lesser General Public
009: * License as published by the Free Software Foundation; either
010: * version 2.1 of the License, or (at your option) any later version.
011: *
012: * This library is distributed in the hope that it will be useful,
013: * but WITHOUT ANY WARRANTY; without even the implied warranty of
014: * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
015: * Lesser General Public License for more details.
016: *
017: * You should have received a copy of the GNU Lesser General Public
018: * License along with this library; if not, write to the Free Software
019: * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
020: *
021: * Redistribution and use of this software and associated documentation ("Software"),
022: * with or without modification, are permitted provided that the following conditions are met:
023: * 1. Redistributions of source code must retain copyright statements and notices.
024: * Redistributions must also contain a copy of this document.
025: * 2. Redistributions in binary form must reproduce the above copyright notice,
026: * this list of conditions and the following disclaimer in the documentation
027: * and/or other materials provided with the distribution.
028: * 3. The name "JAFFA" must not be used to endorse or promote products derived from
029: * this Software without prior written permission. For written permission,
030: * please contact mail to: jaffagroup@yahoo.com.
031: * 4. Products derived from this Software may not be called "JAFFA" nor may "JAFFA"
032: * appear in their names without prior written permission.
033: * 5. Due credit should be given to the JAFFA Project (http://jaffa.sourceforge.net).
034: *
035: * THIS SOFTWARE IS PROVIDED "AS IS" AND ANY EXPRESSED OR IMPLIED
036: * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
037: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
038: * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
039: * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
040: * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
041: * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
042: * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
043: * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
044: * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
045: * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
046: * SUCH DAMAGE.
047: * ====================================================================
048: */
049:
050: package org.jaffa.cache;
051:
052: import java.util.*;
053:
054: /** This implementation of the ICache interface uses the WeakHashMap for caching. <B>Note that this implementation is not synchronized.</B> If multiple threads access this cache concurrently, and at least one of the threads modifies the cache structurally, it must be synchronized externally.
055: *
056: * @author GautamJ
057: */
058: public class WeakCache implements ICache {
059:
060: private Map m_map = null;
061:
062: /** Creates a new instance of SimpleCache */
063: public WeakCache() {
064: m_map = new WeakHashMap();
065: }
066:
067: /** Removes all mappings from this cache.
068: */
069: public void clear() {
070: m_map.clear();
071: }
072:
073: /** Returns true if this cache contains a mapping for the specified key.
074: * @param key key whose presence in this cache is to be tested.
075: * @return true if this cache contains a mapping for the specified key.
076: */
077: public boolean containsKey(Object key) {
078: return m_map.containsKey(key);
079: }
080:
081: /** Returns the value to which cache maps the specified key. Returns null if the cache contains no mapping for this key. A return value of null does not necessarily indicate that the cache contains no mapping for the key; it's also possible that the cache explicitly maps the key to null. The containsKey operation may be used to distinguish these two cases.
082: * @param key key whose associated value is to be returned.
083: * @return the value to which this cache maps the specified key, or null if the cache contains no mapping for this key.
084: */
085: public Object get(Object key) {
086: return m_map.get(key);
087: }
088:
089: /** Returns true if this cache contains no key-value mappings.
090: * @return true if this cache contains no key-value mappings.
091: */
092: public boolean isEmpty() {
093: return m_map.isEmpty();
094: }
095:
096: /** Returns a set view of the keys contained in this cache. The set is backed by the cache, so changes to the cache are reflected in the set, and vice-versa. If the cache is modified while an iteration over the set is in progress, the results of the iteration are undefined.
097: * @return a set view of the keys contained in this cache.
098: */
099: public Set keySet() {
100: return m_map.keySet();
101: }
102:
103: /** Associates the specified value with the specified key in this cache. If the cache previously contained a mapping for this key, the old value is replaced by the specified value.
104: * @param key key with which the specified value is to be associated.
105: * @param value value to be associated with the specified key.
106: */
107: public void put(Object key, Object value) {
108: m_map.put(key, value);
109: }
110:
111: /** Removes the mapping for this key from this cache if it is present.
112: * @param key key whose mapping is to be removed from the cache.
113: */
114: public void remove(Object key) {
115: m_map.remove(key);
116: }
117:
118: /** Returns the number of key-value mappings in this cache.
119: * @return the number of key-value mappings in this cache.
120: */
121: public int size() {
122: return m_map.size();
123: }
124:
125: }
|