1 /*
2 * Copyright 2001-2004 The Apache Software Foundation.
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 package org.apache.log4j;
18
19 import org.apache.log4j.spi.Filter;
20 import org.apache.log4j.spi.ErrorHandler;
21 import org.apache.log4j.spi.LoggingEvent;
22
23 /**
24 * Implement this interface for your own strategies for outputting log
25 * statements.
26 *
27 * @author Ceki Gülcü
28 */
29 public interface Appender {
30
31 /**
32 * Add a filter to the end of the filter list.
33 *
34 * @since 0.9.0
35 */
36 void addFilter(Filter newFilter);
37
38 /**
39 * Returns the head Filter. The Filters are organized in a linked list
40 * and so all Filters on this Appender are available through the result.
41 *
42 * @return the head Filter or null, if no Filters are present
43 * @since 1.1
44 */
45 public Filter getFilter();
46
47 /**
48 * Clear the list of filters by removing all the filters in it.
49 *
50 * @since 0.9.0
51 */
52 public void clearFilters();
53
54 /**
55 * Release any resources allocated within the appender such as file
56 * handles, network connections, etc.
57 * <p/>
58 * <p>It is a programming error to append to a closed appender.
59 *
60 * @since 0.8.4
61 */
62 public void close();
63
64 /**
65 * Log in <code>Appender</code> specific way. When appropriate,
66 * Loggers will call the <code>doAppend</code> method of appender
67 * implementations in order to log.
68 */
69 public void doAppend(LoggingEvent event);
70
71 /**
72 * Get the name of this appender. The name uniquely identifies the
73 * appender.
74 */
75 public String getName();
76
77 /**
78 * Set the {@link ErrorHandler} for this appender.
79 *
80 * @since 0.9.0
81 */
82 public void setErrorHandler(ErrorHandler errorHandler);
83
84 /**
85 * Returns the {@link ErrorHandler} for this appender.
86 *
87 * @since 1.1
88 */
89 public ErrorHandler getErrorHandler();
90
91 /**
92 * Set the {@link Layout} for this appender.
93 *
94 * @since 0.8.1
95 */
96 public void setLayout(Layout layout);
97
98 /**
99 * Returns this appenders layout.
100 *
101 * @since 1.1
102 */
103 public Layout getLayout();
104
105 /**
106 * Set the name of this appender. The name is used by other
107 * components to identify this appender.
108 *
109 * @since 0.8.1
110 */
111 public void setName(String name);
112
113 /**
114 * Configurators call this method to determine if the appender
115 * requires a layout. If this method returns <code>true</code>,
116 * meaning that layout is required, then the configurator will
117 * configure an layout using the configuration information at its
118 * disposal. If this method returns <code>false</code>, meaning that
119 * a layout is not required, then layout configuration will be
120 * skipped even if there is available layout configuration
121 * information at the disposal of the configurator.
122 * <p/>
123 * <p>In the rather exceptional case, where the appender
124 * implementation admits a layout but can also work without it, then
125 * the appender should return <code>true</code>.
126 *
127 * @since 0.8.4
128 */
129 public boolean requiresLayout();
130 }