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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one
3    * or more contributor license agreements.  See the NOTICE file
4    * distributed with this work for additional information
5    * regarding copyright ownership.  The ASF licenses this file
6    * to you under the Apache License, Version 2.0 (the
7    * "License"); you may not use this file except in compliance
8    * with the License.  You may obtain a copy of the License at
9    *
10   *     http://www.apache.org/licenses/LICENSE-2.0
11   *
12   * Unless required by applicable law or agreed to in writing,
13   * software distributed under the License is distributed on an
14   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15   * KIND, either express or implied.  See the License for the
16   * specific language governing permissions and limitations
17   * under the License.
18   */
19  package org.apache.shiro.event.support;
20  
21  import java.util.List;
22  
23  /**
24   * An {@code EventListenerResolver} knows how to resolve (either create or lookup) {@link EventListener} instances
25   * as a result of inspecting a subscriber object, mostly likely a
26   * {@link org.apache.shiro.event.Subscribe Subscribe}-annotated object instance.
27   * <p/>
28   * This interface exists primarily as a support concept for the {@link DefaultEventBus} implementation.  Custom
29   * implementations of this interface can be configured on a {@link DefaultEventBus} instance to determine exactly
30   * how a subscriber receives events.
31   * <p/>
32   * For example, the {@link AnnotationEventListenerResolver AnnotationEventListenerResolver} will inspect a runtime
33   * object for {@link org.apache.shiro.event.Subscribe Subscribe}-annotated methods, and for each method found, return
34   * an {@link EventListener} instance representing the method to invoke.
35   *
36   * @see AnnotationEventListenerResolver
37   * @see SingleArgumentMethodEventListener
38   * @since 1.3
39   */
40  public interface EventListenerResolver {
41  
42      /**
43       * Returns {@link EventListener} instances as a result of inspecting a subscriber object, mostly likely with
44       * {@link org.apache.shiro.event.Subscribe Subscribe}-annotated methods.
45       *
46       * @param instance the subscriber instance for which EventListener instances should be acquired.
47       * @return {@link EventListener} instances as a result of inspecting a subscriber object.
48       */
49      List<EventListener> getEventListeners(Object instance);
50  }