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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    /**
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 }