    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *     http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017package org.apache.commons.configuration2.interpol;
    018
    019import org.apache.commons.text.lookup.StringLookupFactory;
    020
    021/**
    022 * <p>
    023 * A specialized implementation of the {@code Lookup} interface that allows
    024 * access to system properties.
    025 * </p>
    026 * <p>
    027 * This implementation relies on {@code StrLookup.systemPropertiesLookup()} from
    028 * the Commons Lang project to resolve system properties. It can be used for
    029 * referencing system properties in configuration files in an easy way, for
    030 * instance:
    031 * </p>
    032 *
    033 * <pre>
    034 * current.user = ${sys:user.name}
    035 * </pre>
    036 *
    037 * <p>
    038 * {@code SystemPropertiesLookup} is one of the standard lookups that is
    039 * registered per default for each configuration.
    040 * </p>
    041 *
    042 * @since 2.0
    043 * @deprecated Use {@link DefaultLookups#SYSTEM_PROPERTIES}.
    044 */
    045@Deprecated
    046public class SystemPropertiesLookup implements Lookup
    047{
    048    @Override
    049    public Object lookup(final String variable)
    050    {
    051        return StringLookupFactory.INSTANCE.systemPropertyStringLookup().lookup(variable);
    052    }
    053}