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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  
18  package org.apache.log4j;
19  
20  import org.apache.log4j.spi.Filter;
21  import org.apache.log4j.spi.ErrorHandler;
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
47    Filter getFilter();
48  
49    /**
50       Clear the list of filters by removing all the filters in it.
51       
52       @since 0.9.0
53     */
54    public
55    void clearFilters();
56  
57    /**
58       Release any resources allocated within the appender such as file
59       handles, network connections, etc.
60  
61       <p>It is a programming error to append to a closed appender.
62  
63       @since 0.8.4
64    */
65    public
66    void close();
67    
68    /**
69       Log in <code>Appender</code> specific way. When appropriate,
70       Loggers will call the <code>doAppend</code> method of appender
71       implementations in order to log. */
72    public
73    void doAppend(LoggingEvent event);
74  
75  
76    /**
77       Get the name of this appender.
78       @return name, may be null.*/
79    public
80    String getName();
81  
82  
83    /**
84       Set the {@link ErrorHandler} for this appender.
85  
86       @since 0.9.0
87     */
88    public
89    void setErrorHandler(ErrorHandler errorHandler);
90  
91    /**
92       Returns the {@link ErrorHandler} for this appender.
93  
94       @since 1.1
95     */
96    public
97    ErrorHandler getErrorHandler();
98  
99    /**
100      Set the {@link Layout} for this appender.
101 
102      @since 0.8.1
103   */
104   public
105   void setLayout(Layout layout);
106 
107   /**
108      Returns this appenders layout.
109      
110      @since 1.1
111   */
112   public
113   Layout getLayout();
114   
115 
116   /**
117      Set the name of this appender. The name is used by other
118      components to identify this appender.
119 
120      @since 0.8.1
121   */
122   public
123   void setName(String name);
124 
125   /**
126      Configurators call this method to determine if the appender
127     requires a layout. If this method returns <code>true</code>,
128     meaning that layout is required, then the configurator will
129     configure an layout using the configuration information at its
130     disposal.  If this method returns <code>false</code>, meaning that
131     a layout is not required, then layout configuration will be
132     skipped even if there is available layout configuration
133     information at the disposal of the configurator..
134 
135      <p>In the rather exceptional case, where the appender
136      implementation admits a layout but can also work without it, then
137      the appender should return <code>true</code>.
138      
139      @since 0.8.4 */
140   public
141   boolean requiresLayout();
142 }