/* * 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.spi.OptionHandler;import org.apache.log4j.spi.LoggingEvent;/**   Extend this abstract class to create your own log layout format.      @author Ceki G&uuml;lc&uuml;*/  public abstract class Layout implements OptionHandler {  // Note that the line.separator property can be looked up even by  // applets.  public final static String LINE_SEP = System.getProperty("line.separator");  public final static int LINE_SEP_LEN  = LINE_SEP.length();  /**     Implement this method to create your own layout format.  */  abstract  public  String format(LoggingEvent event);  /**     Returns the content type output by this layout. The base class     returns "text/plain".   */  public  String getContentType() {    return "text/plain";  }  /**     Returns the header for the layout format. The base class returns     <code>null</code>.  */  public  String getHeader() {    return null;  }  /**     Returns the footer for the layout format. The base class returns     <code>null</code>.  */  public  String getFooter() {    return null;  }  /**     If the layout handles the throwable object contained within     {@link LoggingEvent}, then the layout should return     <code>false</code>. Otherwise, if the layout ignores throwable     object, then the layout should return <code>true</code>.     <p>The {@link SimpleLayout}, {@link TTCCLayout}, {@link     PatternLayout} all return <code>true</code>. The {@link     org.apache.log4j.xml.XMLLayout} returns <code>false</code>.     @since 0.8.4 */  abstract  public  boolean ignoresThrowable();}