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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       * Get the name of this appender. The name uniquely identifies the
74       * appender.
75       */
76      public String getName();
77  
78      /**
79       * Set the {@link ErrorHandler} for this appender.
80       *
81       * @since 0.9.0
82       */
83      public void setErrorHandler(ErrorHandler errorHandler);
84  
85      /**
86       * Returns the {@link ErrorHandler} for this appender.
87       *
88       * @since 1.1
89       */
90      public ErrorHandler getErrorHandler();
91  
92      /**
93       * Set the {@link Layout} for this appender.
94       *
95       * @since 0.8.1
96       */
97      public void setLayout(Layout layout);
98  
99      /**
100      * Returns this appenders layout.
101      *
102      * @since 1.1
103      */
104     public Layout getLayout();
105 
106     /**
107      * Set the name of this appender. The name is used by other
108      * components to identify this appender.
109      *
110      * @since 0.8.1
111      */
112     public void setName(String name);
113 
114     /**
115      * Configurators call this method to determine if the appender
116      * requires a layout. If this method returns <code>true</code>,
117      * meaning that layout is required, then the configurator will
118      * configure an layout using the configuration information at its
119      * disposal.  If this method returns <code>false</code>, meaning that
120      * a layout is not required, then layout configuration will be
121      * skipped even if there is available layout configuration
122      * information at the disposal of the configurator..
123      * <p/>
124      * <p>In the rather exceptional case, where the appender
125      * implementation admits a layout but can also work without it, then
126      * the appender should return <code>true</code>.
127      *
128      * @since 0.8.4
129      */
130     public boolean requiresLayout();
131 }