Spring源码解读：核心类DefaultListableBeanFactory的继承体系

1 简介

我们常用的ClassPathXmlApplicationContext是AbstractRefreshableApplicationContext的子类，而DefaultListableBeanFactory类型的beanFactory又是AbstractRefreshableApplicationContext的一个成员属性，也就是说ClassPathXmlApplicationContext运用了组合的方式扩展了DefaultListableBeanFactory的功能，使其自身成为了一个上下文容器。
在这里插入图片描述
另外XmlBeanFactory继承自DefaultListableBeanFactory，而DefaultListableBeanFactory是整个bean加载的核心部分，是 Spring 注册及加载 bean 的默认实现.

而对于 XmlBeanFactory与DefaultListableBeanFactory 不同的地方其实是在 XmlBeanFactory 中使用了自定义的XML 读取器XmlBeanDefinitionReader，实现了个性化的BeanDefinitionReader读取DefaultListableBeanFactory继承了 AbstractAutowireCapableBeanFactory 并实现了ConfigurableListableBeanFactory 以及BeanDefinitionRegistry接口。

2 继承层次分析

在这里插入图片描述

DefaultListableBeanFactory的继承体系层次图

各个类的主要功能和API:

1)AliasRegistry

定义对alias的简单增删改等操作

//通用的别名管理接口
    public interface AliasRegistry {


         //Given a name, register an alias for it.
        void registerAlias(String name, String alias);

        /**
         * Remove the specified alias from this registry.
         */
        void removeAlias(String alias);

        /**
         * Determine whether this given name is defines as an alias
         * (as opposed to the name of an actually registered component).
         */
        boolean isAlias(String name);

        /**
         * Return the aliases for the given name, if defined.
         */
        String[] getAliases(String name);
    }

2)SimpleAliasRegistry

主要使用map作为alias的缓存，并对接口AliasRegistry进行实现.
在这里插入图片描述

3)SingletonBeanRegistry

定义对单例的注册及获取

    //Interface that defines a registry for shared bean instances.
    public interface SingletonBeanRegistry {

        /**
         * Register the given existing object as singleton in the bean registry,
         * under the given bean name.
         */
        void registerSingleton(String beanName, Object singletonObject);

        /**
         * Return the (raw) singleton object registered under the given name.
         */
        @Nullable
        Object getSingleton(String beanName);

        /**
         * Check if this registry contains a singleton instance with the given name.
         */
        boolean containsSingleton(String beanName);

        /**
         * Return the names of singleton beans registered in this registry.
         */
        String[] getSingletonNames();

        /**
         * Return the number of singleton beans registered in this registry.
         */
        int getSingletonCount();

        /**
         * Return the singleton mutex used by this registry (for external collaborators).
         */
        Object getSingletonMutex();
    }

4)BeanDefinitionRegistry

定义对BeanDefinition的各种增删改操作

  /**
     * Interface for registries that hold bean definitions, for example RootBeanDefinition
     * and ChildBeanDefinition instances. Typically implemented by BeanFactories that
     * internally work with the AbstractBeanDefinition hierarchy.
     */
    public interface BeanDefinitionRegistry extends AliasRegistry {

        /**
         * Register a new bean definition with this registry.
         * Must support RootBeanDefinition and ChildBeanDefinition.
         */
        void registerBeanDefinition(String beanName, BeanDefinition beanDefinition)
                throws BeanDefinitionStoreException;

        /**
         * Remove the BeanDefinition for the given name.
         */
        void removeBeanDefinition(String beanName) throws NoSuchBeanDefinitionException;

        /**
         * Return the BeanDefinition for the given bean name.
         */
        BeanDefinition getBeanDefinition(String beanName) throws NoSuchBeanDefinitionException;

        /**
         * Check if this registry contains a bean definition with the given name.
         */
        boolean containsBeanDefinition(String beanName);

        /**
         * Return the names of all beans defined in this registry.
         */
        String[] getBeanDefinitionNames();

        /**
         * Return the number of beans defined in the registry.
         */
        int getBeanDefinitionCount();

        /**
         * Determine whether the given bean name is already in use within this registry,
         * i.e. whether there is a local bean or alias registered under this name.
         */
        boolean isBeanNameInUse(String beanName);
    }

5)BeanFactory

定义获取bean及bean的各种属性。
在这里插入图片描述

6)DefaultSingletonBeanRegistry

对接口SingletonBeanRegistry各函数的实现
在这里插入图片描述

7）HierarchicalBeanFactory

扩展了BeanFactory,新增了两个抽象方法，提供了对父工厂parentBeanFactory和内嵌Bean的支持

    /**
     * Sub-interface implemented by bean factories that can be part
     * of a hierarchy.
     */
    public interface HierarchicalBeanFactory extends BeanFactory {

        /**
         * Return the parent bean factory, or {@code null} if there is none.
         */
        BeanFactory getParentBeanFactory();

        /**
         * Return whether the local bean factory contains a bean of the given name,
         * ignoring beans defined in ancestor contexts.
         */
        boolean containsLocalBean(String name);
    }

8)ListableBeanFactory

提供了以类型、名字、注解等条件获取相关bean的各种配置信息的抽象方法。
在这里插入图片描述

9)FactoryBeanRegistrySupport

在DefaultSingletonBeanRegistry基础上增加了对
FactoryBean的特殊处理功能，没有新增的公用API,几乎全是protected级别的方法（主要是对FactoryBean的支持，FactoryBean不返回实例本身，而是返回此工厂方法getBean()的返回对象），以供子类调用或重写。
在这里插入图片描述