/apache-log4j-1.2.17/src/main/java/org/apache/log4j/pattern/LoggingEventPatternConverter.java

 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
18package org.apache.log4j.pattern;
19
20import org.apache.log4j.spi.LoggingEvent;
21
22
23/**
24 * LoggingEventPatternConverter is a base class for pattern converters
25 * that can format information from instances of LoggingEvent.
26 *
27 * @author Curt Arnold
28 *
29 */
30public abstract class LoggingEventPatternConverter extends PatternConverter {
31  /**
32   * Constructs an instance of LoggingEventPatternConverter.
33   * @param name name of converter.
34   * @param style CSS style for output.
35   */
36  protected LoggingEventPatternConverter(
37    final String name, final String style) {
38    super(name, style);
39  }
40
41  /**
42   * Formats an event into a string buffer.
43   * @param event event to format, may not be null.
44   * @param toAppendTo string buffer to which the formatted event will be appended.  May not be null.
45   */
46  public abstract void format(
47    final LoggingEvent event, final StringBuffer toAppendTo);
48
49  /**
50   * {@inheritDoc}
51   */
52  public void format(final Object obj, final StringBuffer output) {
53    if (obj instanceof LoggingEvent) {
54      format((LoggingEvent) obj, output);
55    }
56  }
57
58  /**
59   * Normally pattern converters are not meant to handle Exceptions although
60   * few pattern converters might.
61   *
62   * By examining the return values for this method, the containing layout will
63   * determine whether it handles throwables or not.
64
65   * @return true if this PatternConverter handles throwables
66   */
67  public boolean handlesThrowable() {
68    return false;
69  }
70}