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 package org.apache.log4j;
18
19 import org.apache.log4j.spi.LoggingEvent;
20 import org.apache.logging.log4j.util.Strings;
21
22 /**
23 *
24 */
25 public abstract class Layout {
26
27 public final static String LINE_SEP = Strings.LINE_SEPARATOR;
28
29 /** Note that the line.separator property can be looked up even by applets. */
30 public static final int LINE_SEP_LEN = Strings.LINE_SEPARATOR.length();
31
32 /**
33 * Implement this method to create your own layout format.
34 * @param event The LoggingEvent.
35 * @return The formatted LoggingEvent.
36 */
37 public abstract String format(LoggingEvent event);
38
39 /**
40 * Returns the content type output by this layout. The base class
41 * returns "text/plain".
42 * @return the type of content rendered by the Layout.
43 */
44 public String getContentType() {
45 return "text/plain";
46 }
47
48 /**
49 * Returns the header for the layout format. The base class returns
50 * <code>null</code>.
51 * @return The header.
52 */
53 public String getHeader() {
54 return null;
55 }
56
57 /**
58 * Returns the footer for the layout format. The base class returns
59 * <code>null</code>.
60 * @return The footer.
61 */
62 public String getFooter() {
63 return null;
64 }
65
66
67 /**
68 * If the layout handles the throwable object contained within
69 * {@link LoggingEvent}, then the layout should return
70 * {@code false}. Otherwise, if the layout ignores throwable
71 * object, then the layout should return {@code true}.
72 * If ignoresThrowable is true, the appender is responsible for
73 * rendering the throwable.
74 * <p>
75 * The <a href="/log4j/1.x/apidocs/org/apache/log4j/SimpleLayout.html">SimpleLayout</a>,
76 * <a href="/log4j/1.x/apidocs/org/apache/log4j/TTCCLayout.html">TTCCLayout</a>,
77 * <a href="/log4j/1.x/apidocs/org/apache/log4j/PatternLayout.html">PatternLayout</a>
78 * all return {@code true}. The
79 * <a href="/log4j/1.x/apidocs/org/apache/log4j/xml/XMLLayout.html">XMLLayout</a>
80 * returns {@code false}.
81 * </p>
82 *
83 * @return true if the Layout ignores Throwables.
84 *
85 * @since 0.8.4
86 */
87 public abstract boolean ignoresThrowable();
88 }
89