    001// Copyright 2009, 2012 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
    015package org.apache.tapestry5.commons.internal.services;
    016
    017import java.util.Map;
    018
    019import org.apache.tapestry5.commons.services.InvalidationEventHub;
    020import org.apache.tapestry5.commons.util.CollectionFactory;
    021import org.apache.tapestry5.ioc.annotations.ComponentClasses;
    022import org.apache.tapestry5.ioc.annotations.PostInjection;
    023
    024public class StringInternerImpl implements StringInterner
    025{
    026    private final Map<String, String> cache = CollectionFactory.newConcurrentMap();
    027
    028    @PostInjection
    029    public void setupInvalidation(@ComponentClasses InvalidationEventHub hub)
    030    {
    031        hub.clearOnInvalidation(cache);
    032    }
    033
    034    public String intern(String string)
    035    {
    036        String result = cache.get(string);
    037
    038        // Not yet in the cache?  Add it.
    039
    040        if (result == null)
    041        {
    042            cache.put(string, string);
    043            result = string;
    044        }
    045
    046        return result;
    047    }
    048
    049    public String format(String format, Object... arguments)
    050    {
    051        return intern(String.format(format, arguments));
    052    }
    053}