    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 (Map.Entry<String, String> entry : env.entrySet())
    040            {
    041                symbols.put("env." + entry.getKey(), entry.getValue());
    042            }
    043        }
    044
    045
    046        return symbols.get(symbolName);
    047    }
    048}