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 org.apache.shiro.event.Subscribe;
22 import org.apache.shiro.util.ClassUtils;
23
24 import java.lang.annotation.Annotation;
25 import java.lang.reflect.Method;
26 import java.util.ArrayList;
27 import java.util.Collections;
28 import java.util.List;
29
30 /**
31 * Inspects an object for annotated methods of interest and creates an {@link EventListener} instance for each method
32 * discovered. An event bus will call the resulting listeners as relevant events arrive.
33 * <p/>
34 * The default {@link #setAnnotationClass(Class) annotationClass} is {@link Subscribe}, indicating each
35 * {@link Subscribe}-annotated method will be represented as an EventListener.
36 *
37 * @see SingleArgumentMethodEventListener
38 * @since 1.3
39 */
40 public class AnnotationEventListenerResolver implements EventListenerResolver {
41
42 private Class<? extends Annotation> annotationClass;
43
44 public AnnotationEventListenerResolver() {
45 this.annotationClass = Subscribe.class;
46 }
47
48 /**
49 * Returns a new collection of {@link EventListener} instances, each instance corresponding to an annotated
50 * method discovered on the specified {@code instance} argument.
51 *
52 * @param instance the instance to inspect for annotated event handler methods.
53 * @return a new collection of {@link EventListener} instances, each instance corresponding to an annotated
54 * method discovered on the specified {@code instance} argument.
55 */
56 public List<EventListener> getEventListeners(Object instance) {
57 if (instance == null) {
58 return Collections.emptyList();
59 }
60
61 List<Method> methods = ClassUtils.getAnnotatedMethods(instance.getClass(), getAnnotationClass());
62 if (methods == null || methods.isEmpty()) {
63 return Collections.emptyList();
64 }
65
66 List<EventListener> listeners = new ArrayList<EventListener>(methods.size());
67
68 for (Method m : methods) {
69 listeners.add(new SingleArgumentMethodEventListener(instance, m));
70 }
71
72 return listeners;
73 }
74
75 /**
76 * Returns the type of annotation that indicates a method that should be represented as an {@link EventListener},
77 * defaults to {@link Subscribe}.
78 *
79 * @return the type of annotation that indicates a method that should be represented as an {@link EventListener},
80 * defaults to {@link Subscribe}.
81 */
82 public Class<? extends Annotation> getAnnotationClass() {
83 return annotationClass;
84 }
85
86 /**
87 * Sets the type of annotation that indicates a method that should be represented as an {@link EventListener}.
88 * The default value is {@link Subscribe}.
89 *
90 * @param annotationClass the type of annotation that indicates a method that should be represented as an
91 * {@link EventListener}. The default value is {@link Subscribe}.
92 */
93 public void setAnnotationClass(Class<? extends Annotation> annotationClass) {
94 this.annotationClass = annotationClass;
95 }
96 }