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
015package org.apache.tapestry5.ioc.internal.services;
016
017import org.apache.tapestry5.ioc.internal.util.CollectionFactory;
018import org.apache.tapestry5.ioc.services.SymbolProvider;
019
020import 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 */
028public class SystemEnvSymbolProvider implements SymbolProvider
029{
030    private final Map<String, String> symbols = CollectionFactory.newCaseInsensitiveMap();
031
032    @Override
033    public synchronized String valueForSymbol(String symbolName)
034    {
035        if (symbols.isEmpty())
036        {
037            Map<String, String> env = System.getenv();
038
039            for (String key : env.keySet())
040            {
041                symbols.put("env." + key, env.get(key));
042            }
043        }
044
045
046        return symbols.get(symbolName);
047    }
048}