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