    001    // Copyright 2011 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.ioc.internal.services;
    016
    017    import org.apache.tapestry5.ioc.internal.util.CollectionFactory;
    018    import org.apache.tapestry5.ioc.services.SymbolProvider;
    019
    020    import java.util.Map;
    021
    022    /**
    023     * Provides <em>case insensitive</em> access to  environment variables. Environment variable symbols
    024     * are prefixed with "env.".
    025     *
    026     * @since 5.3
    027     */
    028    public class SystemEnvSymbolProvider implements SymbolProvider
    029    {
    030        private final Map<String, String> symbols = CollectionFactory.newCaseInsensitiveMap();
    031
    032        public synchronized String valueForSymbol(String symbolName)
    033        {
    034            if (symbols.isEmpty())
    035            {
    036                Map<String, String> env = System.getenv();
    037
    038                for (String key : env.keySet())
    039                {
    040                    symbols.put("env." + key, env.get(key));
    041                }
    042            }
    043
    044
    045            return symbols.get(symbolName);
    046        }
    047    }