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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
    18  package org.apache.log4j;
    19
    20  import org.apache.log4j.spi.OptionHandler;
    21  import org.apache.log4j.spi.LoggingEvent;
    22
    23  /***
    24     Extend this abstract class to create your own log layout format.
    25
    26     @author Ceki G&uuml;lc&uuml;
    27
    28  */
    29
    30  public abstract class Layout implements OptionHandler {
    31
    32    // Note that the line.separator property can be looked up even by
    33    // applets.
    34    public final static String LINE_SEP = System.getProperty("line.separator");
    35    public final static int LINE_SEP_LEN  = LINE_SEP.length();
    36
    37
    38    /***
    39       Implement this method to create your own layout format.
    40    */
    41    abstract
    42    public
    43    String format(LoggingEvent event);
    44
    45    /***
    46       Returns the content type output by this layout. The base class
    47       returns "text/plain".
    48    */
    49    public
    50    String getContentType() {
    51      return "text/plain";
    52    }
    53
    54    /***
    55       Returns the header for the layout format. The base class returns
    56       <code>null</code>.  */
    57    public
    58    String getHeader() {
    59      return null;
    60    }
    61
    62    /***
    63       Returns the footer for the layout format. The base class returns
    64       <code>null</code>.  */
    65    public
    66    String getFooter() {
    67      return null;
    68    }
    69
    70
    71
    72    /***
    73       If the layout handles the throwable object contained within
    74       {@link LoggingEvent}, then the layout should return
    75       <code>false</code>. Otherwise, if the layout ignores throwable
    76       object, then the layout should return <code>true</code>.
    77
    78       <p>The {@link SimpleLayout}, {@link TTCCLayout}, {@link
    79       PatternLayout} all return <code>true</code>. The {@link
    80       org.apache.log4j.xml.XMLLayout} returns <code>false</code>.
    81
    82       @since 0.8.4 */
    83    abstract
    84    public
    85    boolean ignoresThrowable();
    86
    87  }