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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", type = "Converter")
27  @ConverterKeys({"C", "class" })
28  public final class ClassNamePatternConverter extends NamePatternConverter {
29  
30      private static final String NA = "?";
31      /**
32       * Private constructor.
33       *
34       * @param options options, may be null.
35       */
36      private ClassNamePatternConverter(
37          final String[] options) {
38          super("Class Name", "class name", options);
39      }
40  
41      /**
42       * Gets an instance of ClassNamePatternConverter.
43       *
44       * @param options options, may be null.
45       * @return instance of pattern converter.
46       */
47      public static ClassNamePatternConverter newInstance(final String[] options) {
48          return new ClassNamePatternConverter(options);
49      }
50  
51      /**
52       * Format a logging event.
53       *
54       * @param event      event to format.
55       * @param toAppendTo string buffer to which class name will be appended.
56       */
57      @Override
58      public void format(final LogEvent event, final StringBuilder toAppendTo) {
59  
60          StackTraceElement element = event.getSource();
61  
62          if (element == null) {
63              toAppendTo.append(NA);
64          } else {
65              toAppendTo.append(abbreviate(element.getClassName()));
66          }
67      }
68  }