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.spi;
19
20 import org.apache.log4j.Appender;
21 import org.apache.log4j.Logger;
22
23
24 /**
25 * Interface used to listen for Logger related events such as
26 * add/remove appender or changing levels. Clients register an instance of
27 * the interface and the instance is called back when the various events occur.
28 * <p>
29 * LoggerRepository provides methods for adding and removing
30 * LoggerEventListener instances.
31 * <p>
32 * When implementing the methods of this interface, it is useful to remember
33 * that the Logger can access the repository using its getRepository()
34 * method.
35 *
36 * @author Ceki Gülcü
37 * @author Mark Womack
38 */
39 public interface LoggerEventListener {
40 /**
41 * Called when an appender is added to the logger.
42 *
43 * @param logger The logger to which the appender was added.
44 * @param appender The appender added to the logger.
45 */
46 void appenderAddedEvent(Logger logger, Appender appender);
47
48 /**
49 * Called when an appender is removed from the logger.
50 *
51 * @param logger The logger from which the appender was removed.
52 * @param appender The appender removed from the logger.
53 */
54 void appenderRemovedEvent(Logger logger, Appender appender);
55
56 /**
57 * Called when level changed on the logger.
58 *
59 * @param logger The logger that changed levels.
60 */
61 void levelChangedEvent(Logger logger);
62 }