SingletonBeanRegistry


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16  
17  package org.springframework.beans.factory.config;
18  
19  /**
20   * Interface that defines a registry for shared bean instances.
21   * Can be implemented by {@link org.springframework.beans.factory.BeanFactory}
22   * implementations in order to expose their singleton management facility
23   * in a uniform manner.
24   *
25   * <p>The {@link ConfigurableBeanFactory} interface extends this interface.
26   *
27   * @author Juergen Hoeller
28   * @since 2.0
29   * @see ConfigurableBeanFactory
30   * @see org.springframework.beans.factory.support.DefaultSingletonBeanRegistry
31   * @see org.springframework.beans.factory.support.AbstractBeanFactory
32   */
33  public interface SingletonBeanRegistry {
34  
35      /**
36       * Register the given existing object as singleton in the bean registry,
37       * under the given bean name.
38       * <p>The given instance is supposed to be fully initialized; the registry
39       * will not perform any initialization callbacks (in particular, it won't
40       * call InitializingBean's <code>afterPropertiesSet</code> method).
41       * The given instance will not receive any destruction callbacks
42       * (like DisposableBean's <code>destroy</code> method) either.
43       * <p>If running within a full BeanFactory: <b>Register a bean definition
44       * instead of an existing instance if your bean is supposed to receive
45       * initialization and/or destruction callbacks.</b>
46       * <p>Typically invoked during registry configuration, but can also be used
47       * for runtime registration of singletons. As a consequence, a registry
48       * implementation should synchronize singleton access; it will have to do
49       * this anyway if it supports a BeanFactory's lazy initialization of singletons.
50       * @param beanName the name of the bean
51       * @param singletonObject the existing singleton object
52       * @see org.springframework.beans.factory.InitializingBean#afterPropertiesSet
53       * @see org.springframework.beans.factory.DisposableBean#destroy
54       * @see org.springframework.beans.factory.support.BeanDefinitionRegistry#registerBeanDefinition
55       */
56      void registerSingleton(String   beanName, Object   singletonObject);
57  
58      /**
59       * Return the (raw) singleton object registered under the given name.
60       * <p>Only checks already instantiated singletons; does not return an Object
61       * for singleton bean definitions which have not been instantiated yet.
62       * <p>The main purpose of this method is to access manually registered singletons
63       * (see {@link #registerSingleton}). Can also be used to access a singleton
64       * defined by a bean definition that already been created, in a raw fashion.
65       * @param beanName the name of the bean to look for
66       * @return the registered singleton object, or <code>null</code> if none found
67       * @see ConfigurableListableBeanFactory#getBeanDefinition
68       */
69      Object   getSingleton(String   beanName);
70  
71      /**
72       * Check if this registry contains a singleton instance with the given name.
73       * <p>Only checks already instantiated singletons; does not return <code>true</code>
74       * for singleton bean definitions which have not been instantiated yet.
75       * <p>The main purpose of this method is to check manually registered singletons
76       * (see {@link #registerSingleton}). Can also be used to check whether a
77       * singleton defined by a bean definition has already been created.
78       * <p>To check whether a bean factory contains a bean definition with a given name,
79       * use ListableBeanFactory's <code>containsBeanDefinition</code>. Calling both
80       * <code>containsBeanDefinition</code> and <code>containsSingleton</code> answers
81       * whether a specific bean factory contains an own bean with the given name.
82       * <p>Use BeanFactory's <code>containsBean</code> for general checks whether the
83       * factory knows about a bean with a given name (whether manually registered singleton
84       * instance or created by bean definition), also checking ancestor factories.
85       * @param beanName the name of the bean to look for
86       * @return if this bean factory contains a singleton instance with the given name
87       * @see #registerSingleton
88       * @see org.springframework.beans.factory.ListableBeanFactory#containsBeanDefinition
89       * @see org.springframework.beans.factory.BeanFactory#containsBean
90       */
91      boolean containsSingleton(String   beanName);
92  
93      /**
94       * Return the names of singleton beans registered in this registry.
95       * <p>Only checks already instantiated singletons; does not return names
96       * for singleton bean definitions which have not been instantiated yet.
97       * <p>The main purpose of this method is to check manually registered singletons
98       * (see {@link #registerSingleton}). Can also be used to check which
99       * singletons defined by a bean definition have already been created.
100      * @return the list of names as String array (never <code>null</code>)
101      * @see #registerSingleton
102      * @see org.springframework.beans.factory.support.BeanDefinitionRegistry#getBeanDefinitionNames
103      * @see org.springframework.beans.factory.ListableBeanFactory#getBeanDefinitionNames
104      */
105     String  [] getSingletonNames();
106 
107     /**
108      * Return the number of singleton beans registered in this registry.
109      * <p>Only checks already instantiated singletons; does not count
110      * singleton bean definitions which have not been instantiated yet.
111      * <p>The main purpose of this method is to check manually registered singletons
112      * (see {@link #registerSingleton}). Can also be used to count the number of
113      * singletons defined by a bean definition that have already been created.
114      * @return the number of singleton beans
115      * @see #registerSingleton
116      * @see org.springframework.beans.factory.support.BeanDefinitionRegistry#getBeanDefinitionCount
117      * @see org.springframework.beans.factory.ListableBeanFactory#getBeanDefinitionCount
118      */
119     int getSingletonCount();
120 
121 }
122
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