/* * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements.  See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You under the Apache License, Version 2.0 * (the "License"); you may not use this file except in compliance with * the License.  You may obtain a copy of the License at *  *      http://www.apache.org/licenses/LICENSE-2.0 *  * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */package org.apache.log4j;import org.apache.log4j.helpers.PatternParser;/**  Example showing how to extend PatternLayout to recognize additional  conversion characters.      <p>In this case MyPatternLayout recognizes %# conversion pattern. It  outputs the value of an internal counter which is also incremented  at each call.  <p>See <a href=doc-files/MyPatternLayout.java><b>source</b></a> code  for more details.  @see MyPatternParser  @see org.apache.log4j.PatternLayout  @author Anders Kristensen */public class MyPatternLayout extends PatternLayout {  public  MyPatternLayout() {    this(DEFAULT_CONVERSION_PATTERN);  }  public  MyPatternLayout(String pattern) {    super(pattern);  }      public  PatternParser createPatternParser(String pattern) {    return new MyPatternParser(      pattern == null ? DEFAULT_CONVERSION_PATTERN : pattern);  }    public  static void main(String[] args) {    Layout layout = new MyPatternLayout("[counter=%.10#] - %m%n");    Logger logger = Logger.getLogger("some.cat");    logger.addAppender(new ConsoleAppender(layout, ConsoleAppender.SYSTEM_OUT));    logger.debug("Hello, log");    logger.info("Hello again...");      }}