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.Layout;
22 import org.apache.log4j.spi.LoggingEvent;
23
24 /**
25 * Implement this interface for your own strategies for outputting log
26 * statements.
27 *
28 * @author Ceki Gülcü
29 */
30 public interface Appender {
31
32 /**
33 * Add a filter to the end of the filter list.
34 *
35 * @since 0.9.0
36 */
37 void addFilter(Filter newFilter);
38
39 /**
40 * Returns the head Filter. The Filters are organized in a linked list
41 * and so all Filters on this Appender are available through the result.
42 *
43 * @return the head Filter or null, if no Filters are present
44 * @since 1.1
45 */
46 public Filter getFilter();
47
48 /**
49 * Clear the list of filters by removing all the filters in it.
50 *
51 * @since 0.9.0
52 */
53 public void clearFilters();
54
55 /**
56 * Release any resources allocated within the appender such as file
57 * handles, network connections, etc.
58 * <p/>
59 * <p>It is a programming error to append to a closed appender.
60 *
61 * @since 0.8.4
62 */
63 public void close();
64
65 /**
66 * Log in <code>Appender</code> specific way. When appropriate,
67 * Loggers will call the <code>doAppend</code> method of appender
68 * implementations in order to log.
69 */
70 public void doAppend(LoggingEvent event);
71
72
73 /**
74 * Get the name of this appender. The name uniquely identifies the
75 * appender.
76 */
77 public String getName();
78
79
80 /**
81 * Set the {@link ErrorHandler} for this appender.
82 *
83 * @since 0.9.0
84 */
85 public void setErrorHandler(ErrorHandler errorHandler);
86
87 /**
88 * Returns the {@link ErrorHandler} for this appender.
89 *
90 * @since 1.1
91 */
92 public ErrorHandler getErrorHandler();
93
94 /**
95 * Set the {@link Layout} for this appender.
96 *
97 * @since 0.8.1
98 */
99 public void setLayout(Layout layout);
100
101 /**
102 * Returns this appenders layout.
103 *
104 * @since 1.1
105 */
106 public Layout getLayout();
107
108
109 /**
110 * Set the name of this appender. The name is used by other
111 * components to identify this appender.
112 *
113 * @since 0.8.1
114 */
115 public void setName(String name);
116
117 /**
118 * Configurators call this method to determine if the appender
119 * requires a layout. If this method returns <code>true</code>,
120 * meaning that layout is required, then the configurator will
121 * configure an layout using the configuration information at its
122 * disposal. If this method returns <code>false</code>, meaning that
123 * a layout is not required, then layout configuration will be
124 * skipped even if there is available layout configuration
125 * information at the disposal of the configurator..
126 * <p/>
127 * <p>In the rather exceptional case, where the appender
128 * implementation admits a layout but can also work without it, then
129 * the appender should return <code>true</code>.
130 *
131 * @since 0.8.4
132 */
133 public boolean requiresLayout();
134 }