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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.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 }