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1 /**
2  * Copyright (C) 2006 Google Inc.
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 com.google.inject.spring;
18 
19 import static com.google.common.base.Preconditions.checkNotNull;
20 
21 import com.google.inject.Binder;
22 import com.google.inject.Inject;
23 import com.google.inject.Provider;
24 import com.google.inject.name.Names;
25 
26 import org.springframework.beans.factory.BeanFactory;
27 import org.springframework.beans.factory.ListableBeanFactory;
28 
29 /**
30  * Integrates Guice with Spring.
31  *
32  * @author crazybob@google.com (Bob Lee)
33  */
34 public class SpringIntegration {
SpringIntegration()35   private SpringIntegration() {}
36 
37   /**
38    * Creates a provider which looks up objects from Spring using the given name.
39    * Expects a binding to {@link
40    * org.springframework.beans.factory.BeanFactory}. Example usage:
41    *
42    * <pre>
43    * bind(DataSource.class)
44    *   .toProvider(fromSpring(DataSource.class, "dataSource"));
45    * </pre>
46    */
fromSpring(Class<T> type, String name)47   public static <T> Provider<T> fromSpring(Class<T> type, String name) {
48     return new InjectableSpringProvider<T>(type, name);
49   }
50 
51   /**
52    * Binds all Spring beans from the given factory by name. For a Spring bean
53    * named "foo", this method creates a binding to the bean's type and
54    * {@code @Named("foo")}.
55    *
56    * @see com.google.inject.name.Named
57    * @see com.google.inject.name.Names#named(String)
58    */
bindAll(Binder binder, ListableBeanFactory beanFactory)59   public static void bindAll(Binder binder, ListableBeanFactory beanFactory) {
60     binder = binder.skipSources(SpringIntegration.class);
61 
62     for (String name : beanFactory.getBeanDefinitionNames()) {
63       Class<?> type = beanFactory.getType(name);
64       bindBean(binder, beanFactory, name, type);
65     }
66   }
67 
bindBean(Binder binder, ListableBeanFactory beanFactory, String name, Class<T> type)68   static <T> void bindBean(Binder binder, ListableBeanFactory beanFactory,
69       String name, Class<T> type) {
70     SpringProvider<T> provider
71         = SpringProvider.newInstance(type, name);
72     try {
73       provider.initialize(beanFactory);
74     }
75     catch (Exception e) {
76       binder.addError(e);
77       return;
78     }
79 
80     binder.bind(type)
81         .annotatedWith(Names.named(name))
82         .toProvider(provider);
83   }
84 
85   static class SpringProvider<T> implements Provider<T> {
86 
87     BeanFactory beanFactory;
88     boolean singleton;
89     final Class<T> type;
90     final String name;
91 
SpringProvider(Class<T> type, String name)92     public SpringProvider(Class<T> type, String name) {
93       this.type = checkNotNull(type, "type");
94       this.name = checkNotNull(name, "name");
95     }
96 
newInstance(Class<T> type, String name)97     static <T> SpringProvider<T> newInstance(Class<T> type, String name) {
98       return new SpringProvider<T>(type, name);
99     }
100 
initialize(BeanFactory beanFactory)101     void initialize(BeanFactory beanFactory) {
102       this.beanFactory = beanFactory;
103       if (!beanFactory.isTypeMatch(name, type)) {
104         throw new ClassCastException("Spring bean named '" + name
105             + "' does not implement " + type.getName() + ".");
106       }
107       singleton = beanFactory.isSingleton(name);
108     }
109 
get()110     public T get() {
111       return singleton ? getSingleton() : type.cast(beanFactory.getBean(name));
112     }
113 
114     volatile T instance;
115 
getSingleton()116     private T getSingleton() {
117       if (instance == null) {
118         instance = type.cast(beanFactory.getBean(name));
119       }
120       return instance;
121     }
122   }
123 
124   static class InjectableSpringProvider<T> extends SpringProvider<T> {
125 
InjectableSpringProvider(Class<T> type, String name)126     InjectableSpringProvider(Class<T> type, String name) {
127       super(type, name);
128     }
129 
130     @Inject
131     @Override
initialize(BeanFactory beanFactory)132     void initialize(BeanFactory beanFactory) {
133       super.initialize(beanFactory);
134     }
135   }
136 }
137