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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    *      http://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.logging.log4j.core.lookup;
18  
19  import org.apache.logging.log4j.core.LogEvent;
20  import org.apache.logging.log4j.core.config.plugins.Plugin;
21  
22  /**
23   * Looks up keys from environment variables.
24   */
25  @Plugin(name = "env", type = "Lookup")
26  public class EnvironmentLookup implements StrLookup {
27  
28      /**
29       * Get the value of the environment variable.
30       * @param key  the key to be looked up, may be null
31       * @return The value of the environment variable.
32       */
33      public String lookup(final String key) {
34          return System.getenv(key);
35      }
36  
37      /**
38       * Get the value of the environment variable.
39       * @param event The current LogEvent (is ignored by this StrLookup).
40       * @param key  the key to be looked up, may be null
41       * @return The value of the environment variable.
42       */
43      public String lookup(final LogEvent event, final String key) {
44          return System.getenv(key);
45      }
46  }