    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    }