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    }