001    /*
002     * Copyright 2001-2004 The Apache Software Foundation
003     *
004     * Licensed under the Apache License, Version 2.0 (the "License");
005     * you may not use this file except in compliance with the License.
006     * You may obtain a copy of the License at
007     *
008     *     http://www.apache.org/licenses/LICENSE-2.0
009     *
010     * Unless required by applicable law or agreed to in writing, software
011     * distributed under the License is distributed on an "AS IS" BASIS,
012     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013     * See the License for the specific language governing permissions and
014     * limitations under the License.
015     */
016    package org.apache.commons.cache;
017    
018    import java.io.Serializable;
019    
020    /**
021     * A {@link Cache} that doesn't.
022     * @version $Id: NoOpCache.java 155435 2005-02-26 13:17:27Z dirkv $
023     * @author Rodney Waldhoff
024     */
025    public class NoOpCache extends BaseCache implements Cache {
026      /** Returns <tt>false</tt>. */
027      public boolean store(Serializable key, Serializable val, Long expiry, Long cost, Serializable group) {
028        broadcastStoreRequested(key,val,expiry,cost,group);
029        broadcastNotStored(key,val,expiry,cost,group);
030        return false;
031      }
032    
033      /** Returns <tt>null</tt>. */
034      public Serializable retrieve(Serializable key) {
035        broadcastRetrieveRequested(key);
036        broadcastNotRetrieved(key);
037        return null;
038      }
039    
040      /** Returns an empty array. */
041      public Serializable[] getKeysForGroup(Serializable group) {
042        return new Serializable[0];
043      }
044    
045      /** Returns <tt>false</tt> */
046      public boolean contains(Serializable key) {
047        return false;
048      }
049    
050      /** No-op. */
051      public void clear(Serializable key) {
052      }
053    
054      /** No-op. */
055      public void clearGroup(Serializable group) {
056      }
057    
058      /** No-op. */
059      public void clear() {
060      }
061    
062      /** Throws {@link UnsupportedOperationException} */
063      public long getStat(CacheStat stat) throws UnsupportedOperationException {
064        throw new UnsupportedOperationException();
065      }
066    }