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1   /*
2    * Copyright (C) 2012-2024 RRiBbit.org
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    * https://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  package org.rribbit.creation;
17  
18  import java.util.Collection;
19  import java.util.List;
20  import java.util.concurrent.CopyOnWriteArrayList;
21  
22  import org.rribbit.Listener;
23  import org.rribbit.ListenerObject;
24  import org.slf4j.Logger;
25  import org.slf4j.LoggerFactory;
26  import org.springframework.beans.factory.NoSuchBeanDefinitionException;
27  import org.springframework.context.ApplicationContext;
28  import org.springframework.context.ApplicationContextAware;
29  import org.springframework.context.ApplicationListener;
30  import org.springframework.context.event.ContextRefreshedEvent;
31  
32  /**
33   * This {@link ListenerObjectCreator} creates {@link ListenerObject}s from classes. Users can pass in {@link Class}es or packagenames and this class will scan the {@link Class}es
34   * and create {@link ListenerObject}s for the public methods that are annotated with {@link Listener}. Note that public methods inherited from superclasses and superinterfaces will also be
35   * scanned. This means that users must take care not to scan a method twice, once as a method of a class and once as a method of a superclass, by passing a class/interface and its
36   * superclass/superinterface separately to this {@link ListenerObjectCreator}.
37   * <p />
38   * Please note that in Java, method annotations are NOT inherited. This means that, if you override/implement a method in a subclass or subinterface, and the overriding/implementing method
39   * does not have the annotation, then that method will not inherit it. If a class or interface just inherits a method, without overriding it, then the annotation WILL exist.
40   * <p />
41   * To get the actual {@link Object}s that the listeners run on, this will attempt to get a bean for a certain {@link Class} from the Spring Configuration.
42   * When no suitable bean can be found, the {@link Class} will simply be ignored.
43   * <p />
44   * When the classnames and/or packagenames are set, the classes/packagenames are accumulated into {@link Collection}s, but actual processing of them will be done once the entire Spring
45   * Configuration is initialized. This is because this class needs other Spring Beans from the configuration to initialize the {@link ListenerObject}s.
46   * <p />
47   * By default, subpackages of packages are not scanned. This can be changed by using the {@link #setScanSubpackages(boolean)} method.
48   * <p />
49   * NOTE: When using interface-based Spring Proxy's, you have to declare your {@link Listener} annotations on the interface-methods, not the class methods. RRiBbit does not even need to
50   * know about the implementing classes, it will simply ask Spring for a bean that implements the interface that the method is declared in.
51   *
52   * @author G.J. Schouten
53   *
54   */
55  public class SpringBeanClassBasedListenerObjectCreator extends AbstractClassBasedListenerObjectCreator implements ApplicationContextAware, ApplicationListener<ContextRefreshedEvent> {
56  
57  	private static final Logger log = LoggerFactory.getLogger(SpringBeanClassBasedListenerObjectCreator.class);
58  
59  	protected Collection<Class<?>> classesToBeProcessed;
60  	protected Collection<String> packageNamesToBeProcessed;
61  	protected Collection<Class<?>> classesToBeExcluded;
62  	protected boolean scanSubpackages;
63  
64  	protected ApplicationContext applicationContext;
65  
66  	/**
67  	 * Constructors of superclass are not copied, since that would make declaring a bean of this type in the Spring configuration quite verbose. Use the provided setters instead.
68  	 */
69  	public SpringBeanClassBasedListenerObjectCreator() {
70  		classesToBeProcessed = new CopyOnWriteArrayList<>();
71  		packageNamesToBeProcessed = new CopyOnWriteArrayList<>();
72  		classesToBeExcluded = new CopyOnWriteArrayList<>();
73  		scanSubpackages = false;
74  	}
75  
76  	/**
77  	 * Set the classNames that are to be processed by calling {@link #addClass(Class)} once the Spring Configuration is initialized.
78  	 *
79  	 * @param classNames
80  	 */
81  	public void setClassNames(List<String> classNames) {
82  
83  		for(String className : classNames) {
84  			try {
85  				classesToBeProcessed.add(Class.forName(className));
86  			} catch(Exception e) {
87  				throw new RuntimeException("Instantiation of Class object for class '" + className + "' failed", e);
88  			}
89  		}
90  	}
91  
92  	/**
93  	 * Set the packageNames that are to be processed by calling {@link #addPackage(String, boolean)} once the Spring Configuration is initialized.
94  	 *
95  	 * @param packageNames
96  	 */
97  	public void setPackageNames(List<String> packageNames) {
98  
99  		packageNamesToBeProcessed.addAll(packageNames);
100 	}
101 
102 	/**
103 	 * Sets the classes that should be exluced when the packages set with {@link #setPackageNames(List)} are scanned.
104 	 *
105 	 * @param excludedClasses
106 	 */
107 	public void setExcludedClasses(Collection<Class<?>> excludedClasses) {
108 
109 		classesToBeExcluded.addAll(excludedClasses);
110 	}
111 
112 	/**
113 	 * Sets whether subpackages need to be scanned too. The default is false.
114 	 *
115 	 * @param scanSubpackages
116 	 */
117 	public void setScanSubpackages(boolean scanSubpackages) {
118 		this.scanSubpackages = scanSubpackages;
119 	}
120 
121 	@Override
122 	protected Object getTargetObjectForClass(Class<?> clazz) {
123 
124 		try {
125 			log.debug("Attempting to get bean of class '{}'", clazz.getName());
126 			return applicationContext.getBean(clazz);
127 		} catch(NoSuchBeanDefinitionException e) {
128 			log.debug("No suitable bean found, returning null");
129 			return null;
130 		}
131 	}
132 
133 	@Override
134 	public void setApplicationContext(ApplicationContext applicationContext) {
135 		this.applicationContext = applicationContext;
136 	}
137 
138 	/**
139 	 * When the Spring Configuration is reloaded, all {@link ListenerObject}s contained in this {@link ListenerObjectCreator} are dropped, and new ones are created from the classNames
140 	 * and packageNames set in this bean. This means that if you added listeners to this object with one of the methods of one of the superclasses, such as {@link #addClass(Class)},
141 	 * {@link #addObject(Object)} or {@link #addPackage(String, boolean)}, all the {@link ListenerObject}s that resulted from those calls will no longer be there after this call.
142 	 * <p />
143 	 * This is by design. The reason for doing this is because a {@link ContextRefreshedEvent} represents a total refresh of all objects in the application, erasing previous state. If you
144 	 * do not want this, you can extend this class and override the three mentioned add* methods. Each of them must then add the {@link Class}es and packageNames it processes to the
145 	 * {@link Collection}s in this object, before calling super.
146 	 *
147 	 * @param contextRefreshedEvent
148 	 */
149 	@Override
150 	public void onApplicationEvent(ContextRefreshedEvent contextRefreshedEvent) {
151 
152 		if(contextRefreshedEvent.getApplicationContext().equals(applicationContext)) { //Only do this for this ApplicationContext, not for child contexts
153 			log.debug("Clearing existing ListenerObjects");
154 			listenerObjects.clear();
155 
156 			log.debug("Adding original classes");
157 			for(Class<?> clazz : classesToBeProcessed) {
158 				this.addClass(clazz);
159 			}
160 
161 			log.debug("Adding original classes to be excluded");
162 			for(Class<?> clazz : classesToBeExcluded) {
163 				this.excludeClass(clazz);
164 			}
165 
166 			log.debug("Adding original packages");
167 			for(String packageName : packageNamesToBeProcessed) {
168 				this.addPackage(packageName, scanSubpackages);
169 			}
170 		}
171 	}
172 }