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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.pattern;
18  
19  import org.apache.logging.log4j.core.LogEvent;
20  import org.apache.logging.log4j.core.config.plugins.Plugin;
21  
22  
23  /**
24   * Formats the class name of the site of the logging request.
25   */
26  @Plugin(name = "ClassNamePatternConverter", category = PatternConverter.CATEGORY)
27  @ConverterKeys({ "C", "class" })
28  public final class ClassNamePatternConverter extends NamePatternConverter {
29  
30      private static final String NA = "?";
31  
32      /**
33       * Private constructor.
34       *
35       * @param options options, may be null.
36       */
37      private ClassNamePatternConverter(
38          final String[] options) {
39          super("Class Name", "class name", options);
40      }
41  
42      /**
43       * Gets an instance of ClassNamePatternConverter.
44       *
45       * @param options options, may be null.
46       * @return instance of pattern converter.
47       */
48      public static ClassNamePatternConverter newInstance(final String[] options) {
49          return new ClassNamePatternConverter(options);
50      }
51  
52      /**
53       * Format a logging event.
54       *
55       * @param event      event to format.
56       * @param toAppendTo string buffer to which class name will be appended.
57       */
58      @Override
59      public void format(final LogEvent event, final StringBuilder toAppendTo) {
60          final StackTraceElement element = event.getSource();
61          if (element == null) {
62              toAppendTo.append(NA);
63          } else {
64              toAppendTo.append(abbreviate(element.getClassName()));
65          }
66      }
67  }