1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * https://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.configuration2.interpol;
18
19 import org.apache.commons.text.lookup.StringLookupFactory;
20
21 /**
22 * <p>
23 * A specialized implementation of the {@code Lookup} interface that allows access to system properties.
24 * </p>
25 * <p>
26 * This implementation relies on {@code StrLookup.systemPropertiesLookup()} from the Commons Lang project to resolve
27 * system properties. It can be used for referencing system properties in configuration files in an easy way, for
28 * instance:
29 * </p>
30 *
31 * <pre>
32 * current.user = ${sys:user.name}
33 * </pre>
34 *
35 * <p>
36 * {@code SystemPropertiesLookup} is one of the standard lookups that is registered per default for each configuration.
37 * </p>
38 *
39 * @since 2.0
40 * @deprecated Use {@link DefaultLookups#SYSTEM_PROPERTIES}.
41 */
42 @Deprecated
43 public class SystemPropertiesLookup implements Lookup {
44 @Override
45 public Object lookup(final String variable) {
46 return StringLookupFactory.INSTANCE.systemPropertyStringLookup().lookup(variable);
47 }
48 }