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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.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      /**
73       * Get the name of this appender.
74       *
75       * @return name, may be null.
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},
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}, 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}.
130      *
131      * @since 0.8.4
132      */
133     public boolean requiresLayout();
134 }
135