001    // Copyright 2009 The Apache Software Foundation
002    //
003    // Licensed under the Apache License, Version 2.0 (the "License");
004    // you may not use this file except in compliance with the License.
005    // You may obtain a copy of the License at
006    //
007    //     http://www.apache.org/licenses/LICENSE-2.0
008    //
009    // Unless required by applicable law or agreed to in writing, software
010    // distributed under the License is distributed on an "AS IS" BASIS,
011    // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012    // See the License for the specific language governing permissions and
013    // limitations under the License.
014    
015    package org.apache.tapestry5.internal.services;
016    
017    import org.apache.tapestry5.ioc.internal.util.CollectionFactory;
018    import org.apache.tapestry5.services.InvalidationListener;
019    
020    import java.util.Map;
021    
022    public class StringInternerImpl implements StringInterner, InvalidationListener
023    {
024        private final Map<String, String> cache = CollectionFactory.newConcurrentMap();
025    
026        public void objectWasInvalidated()
027        {
028            cache.clear();
029        }
030    
031        public String intern(String string)
032        {
033            String result = cache.get(string);
034    
035            // Not yet in the cache?  Add it.
036    
037            if (result == null)
038            {
039                cache.put(string, string);
040                result = string;
041            }
042    
043            return result;
044        }
045    
046        public String format(String format, Object... arguments)
047        {
048            return intern(String.format(format, arguments));
049        }
050    }