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.Map;
20
21 import org.apache.logging.log4j.core.LogEvent;
22 import org.apache.logging.log4j.core.config.plugins.Plugin;
23
24 /**
25 * A map-based lookup for main arguments.
26 *
27 * See {@link #setMainArguments(String[])}.
28 *
29 * @since 2.4
30 */
31 @Plugin(name = "main", category = StrLookup.CATEGORY)
32 public class MainMapLookup extends MapLookup {
33
34 /**
35 * A singleton used by a main method to save its arguments.
36 */
37 static final MapLookup MAIN_SINGLETON = new MapLookup(MapLookup.newMap(0));
38
39 /**
40 * An application's {@code public static main(String[])} method calls this method to make its main arguments
41 * available for lookup with the prefix {@code main}.
42 * <p>
43 * The map provides two kinds of access: First by index, starting at {@code "0"}, {@code "1"} and so on. For
44 * example, the command line {@code --file path/file.txt -x 2} can be accessed from a configuration file with:
45 * </p>
46 * <ul>
47 * <li>{@code "main:0"} = {@code "--file"}</li>
48 * <li>{@code "main:1"} = {@code "path/file.txt"}</li>
49 * <li>{@code "main:2"} = {@code "-x"}</li>
50 * <li>{@code "main:3"} = {@code "2"}</li>
51 * </ul>
52 * <p>
53 * Second using the argument at position n as the key to access the value at n+1.
54 * </p>
55 * <ul>
56 * <li>{@code "main:--file"} = {@code "path/file.txt"}</li>
57 * <li>{@code "main:-x"} = {@code "2"}</li>
58 * </ul>
59 *
60 * @param args
61 * An application's {@code public static main(String[])} arguments.
62 */
63 public static void setMainArguments(final String... args) {
64 if (args == null) {
65 return;
66 }
67 initMap(args, MainMapLookup.MAIN_SINGLETON.getMap());
68 }
69
70 /**
71 * Constructor when used directly as a plugin.
72 */
73 public MainMapLookup() {
74 // no-init
75 }
76
77 public MainMapLookup(final Map<String, String> map) {
78 super(map);
79 }
80
81 @Override
82 public String lookup(final LogEvent event, final String key) {
83 return MAIN_SINGLETON.getMap().get(key);
84 }
85
86 @Override
87 public String lookup(final String key) {
88 return MAIN_SINGLETON.getMap().get(key);
89 }
90
91 }