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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 java.util.HashMap;
20  import java.util.List;
21  import java.util.Map;
22  
23  import org.apache.logging.log4j.core.LogEvent;
24  import org.apache.logging.log4j.core.config.plugins.Plugin;
25  import org.apache.logging.log4j.message.MapMessage;
26  
27  /**
28   * A map-based lookup.
29   */
30  @Plugin(name = "map", category = StrLookup.CATEGORY)
31  public class MapLookup implements StrLookup {
32  
33      /**
34       * Map keys are variable names and value.
35       */
36      private final Map<String, String> map;
37  
38      /**
39       * Constructor when used directly as a plugin.
40       */
41      public MapLookup() {
42          this.map = null;
43      }
44  
45      /**
46       * Creates a new instance backed by a Map. Used by the default lookup.
47       *
48       * @param map
49       *        the map of keys to values, may be null
50       */
51      public MapLookup(final Map<String, String> map) {
52          this.map = map;
53      }
54  
55      static Map<String, String> initMap(final String[] srcArgs, final Map<String, String> destMap) {
56          for (int i = 0; i < srcArgs.length; i++) {
57              final int next = i + 1;
58              final String value = srcArgs[i];
59              destMap.put(Integer.toString(i), value);
60              destMap.put(value, next < srcArgs.length ? srcArgs[next] : null);
61          }
62          return destMap;
63      }
64  
65      static HashMap<String, String> newMap(final int initialCapacity) {
66          return new HashMap<>(initialCapacity);
67      }
68  
69      /**
70       * An application's {@code public static main(String[])} method calls this method to make its main arguments
71       * available for lookup with the prefix {@code main}.
72       * <p>
73       * The map provides two kinds of access: First by index, starting at {@code "0"}, {@code "1"} and so on. For
74       * example, the command line {@code --file path/file.txt -x 2} can be accessed from a configuration file with:
75       * </p>
76       * <ul>
77       * <li>{@code "main:0"} = {@code "--file"}</li>
78       * <li>{@code "main:1"} = {@code "path/file.txt"}</li>
79       * <li>{@code "main:2"} = {@code "-x"}</li>
80       * <li>{@code "main:3"} = {@code "2"}</li>
81       * </ul>
82       * <p>
83       * Second using the argument at position n as the key to access the value at n+1.
84       * </p>
85       * <ul>
86       * <li>{@code "main:--file"} = {@code "path/file.txt"}</li>
87       * <li>{@code "main:-x"} = {@code "2"}</li>
88       * </ul>
89       *
90       * @param args
91       *        An application's {@code public static main(String[])} arguments.
92       * @since 2.1
93       * @deprecated As of 2.4, use {@link MainMapLookup#setMainArguments(String[])}
94       */
95      @Deprecated
96      public static void setMainArguments(final String... args) {
97          MainMapLookup.setMainArguments(args);
98      }
99  
100     static Map<String, String> toMap(final List<String> args) {
101         if (args == null) {
102             return null;
103         }
104         final int size = args.size();
105         return initMap(args.toArray(new String[size]), newMap(size));
106     }
107 
108     static Map<String, String> toMap(final String[] args) {
109         if (args == null) {
110             return null;
111         }
112         return initMap(args, newMap(args.length));
113     }
114 
115     protected Map<String, String> getMap() {
116         return map;
117     }
118 
119     @Override
120     public String lookup(final LogEvent event, final String key) {
121         final boolean isMapMessage = event.getMessage() instanceof MapMessage;
122         if (map == null && !isMapMessage) {
123             return null;
124         }
125         if (map != null && map.containsKey(key)) {
126             final String obj = map.get(key);
127             if (obj != null) {
128                 return obj;
129             }
130         }
131         if (isMapMessage) {
132             return ((MapMessage) event.getMessage()).get(key);
133         }
134         return null;
135     }
136 
137     /**
138      * Looks up a String key to a String value using the map.
139      * <p>
140      * If the map is null, then null is returned. The map result object is converted to a string using toString().
141      * </p>
142      *
143      * @param key
144      *        the key to be looked up, may be null
145      * @return the matching value, null if no match
146      */
147     @Override
148     public String lookup(final String key) {
149         if (map == null) {
150             return null;
151         }
152         return map.get(key);
153     }
154 
155 }