    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
    18  package org.apache.log4j;
    19
    20  import org.apache.log4j.helpers.FormattingInfo;
    21  import org.apache.log4j.helpers.PatternConverter;
    22  import org.apache.log4j.helpers.PatternParser;
    23  import org.apache.log4j.spi.LoggingEvent;
    24
    25  /**
    26    Example showing how to extend PatternParser to recognize additional
    27    conversion characters.  The examples shows that minimum and maximum
    28    width and alignment settings apply for "extension" conversion
    29    characters just as they do for PatternLayout recognized characters.
    30
    31    <p>In this case MyPatternParser recognizes %# and outputs the value
    32    of an internal counter which is also incremented at each call.
    33
    34    See <a href=doc-files/MyPatternParser.java><b>source</b></a> code
    35     for more details.
    36
    37    @see org.apache.log4j.examples.MyPatternLayout
    38    @see org.apache.log4j.helpers.PatternParser
    39    @see org.apache.log4j.PatternLayout
    40
    41    @author Anders Kristensen
    42  */
    43  public class MyPatternParser extends PatternParser {
    44
    45    int counter = 0;
    46
    47    public
    48    MyPatternParser(String pattern) {
    49      super(pattern);
    50    }
    51
    52    public
    53    void finalizeConverter(char c) {
    54      if (c == '#') {
    55        addConverter(new UserDirPatternConverter(formattingInfo));
    56        currentLiteral.setLength(0);
    57      } else {
    58        super.finalizeConverter(c);
    59      }
    60    }
    61
    62    private class UserDirPatternConverter extends PatternConverter {
    63      UserDirPatternConverter(FormattingInfo formattingInfo) {
    64        super(formattingInfo);
    65      }
    66
    67      public
    68      String convert(LoggingEvent event) {
    69        return String.valueOf(++counter);
    70      }
    71    }
    72  }