【Spring源码解析】 IOC 初始化流程分析

迈不过友情╰ 2023-07-11 06:08 122阅读 0赞

# 1 .AbstractApplicationContext prepareBeanFactory #

@Override
        public void refresh() throws BeansException, IllegalStateException { 
            synchronized (this.startupShutdownMonitor) { 
                //刷新前预处理
                prepareRefresh();
    
                //获取beanFactory实例。(DefaultListableBeanFactory)
                ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();
    
                //beanFactory属性赋值
                prepareBeanFactory(beanFactory);
    
                try { 
                    // 子类通过重写这个方法在BeanFactory创建并预准备完成以后做进一步设置
                    postProcessBeanFactory(beanFactory);
    
                    // 调用实现BeanDefinitionRegistryPostProcessor，BeanFactoryPostProcessor 接口的类相关方法
                    invokeBeanFactoryPostProcessors(beanFactory);
                   
                    // 注册实现了BeanPostProcessor接口的Bean
                    registerBeanPostProcessors(beanFactory);
    
                    // 标签国际化资源，初始化MessageSource组件
                    initMessageSource();
      
                    // 创建事件广播器
                    initApplicationEventMulticaster();
      
                    // 空方法，留给子容器实现，在容器刷新的时候可以子定义逻辑 
                    onRefresh();
      
                   // 注册监听器事件
                    registerListeners();
     
                   // 单例模式bean的注册
                    finishBeanFactoryInitialization(beanFactory);
    
                    // 刷新完成容器
                    finishRefresh();
                }
                catch (BeansException ex) { 
                    if (logger.isWarnEnabled()) { 
                        logger.warn("Exception encountered during context initialization - " +
                                "cancelling refresh attempt: " + ex);
                    }
                    // Destroy already created singletons to avoid dangling resources.
                    destroyBeans();
                    // Reset 'active' flag.
                    cancelRefresh(ex);
                    // Propagate exception to caller.
                    throw ex;
                }
                finally { 
                    // Reset common introspection caches in Spring's core, since we
                    // might not ever need metadata for singleton beans anymore...
                    resetCommonCaches();
                }
            }
        }

# 2 核心方法解析 #

# 2.1 obtainFreshBeanFactory() 获取BeanFactory #

(1) AbstractApplicationContext obtainFreshBeanFactory

protected ConfigurableListableBeanFactory obtainFreshBeanFactory() { 
       //刷新容器
       refreshBeanFactory();
       //获取GenericApplicationContext创建的容器
       ConfigurableListableBeanFactory beanFactory = getBeanFactory();
       if (logger.isDebugEnabled()) { 
          logger.debug("Bean factory for " + getDisplayName() + ": " + beanFactory);
       }
       return beanFactory;
    }

GenericApplicationContext refreshBeanFactory()  
![在这里插入图片描述][20200304144741793.png]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM0MTI1OTk5_size_16_color_FFFFFF_t_70]

## 2.2 invokeBeanFactoryPostProcessors(beanFactory) ##

实际调用PostProcessorRegistrationDelegate invokeBeanFactoryPostProcessors
    (1) 调用实现BeanDefinitionRegistryPostProcessor接口的postProcessBeanDefinitionRegistry，postProcessBeanFactory方法
    (2) 调用实现类BeanFactoryPostProcessor接口的postProcessBeanFactory方法
     PS：BeanFactoryPostProcessor源码机票  -------> https://blog.csdn.net/qq_34125999/article/details/104645988

## 2.3 registerBeanPostProcessors(beanFactory); ##

实际调用PostProcessorRegistrationDelegate  registerBeanPostProcessors，其作用就是给工厂中添加实现了BeanPostProcessor接口的bean
    PS：源码机票  ------->  https://blog.csdn.net/qq_34125999/article/details/104572875

## 2.4 finishBeanFactoryInitialization(beanFactory); ##

完成单实例Bean的注册。
    PS：源码机票  ------->  https://blog.csdn.net/qq_34125999/article/details/104547157

# 3 单例Bean注册的位置 #

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM0MTI1OTk5_size_16_color_FFFFFF_t_70 1]  
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[20200304144741793.png]: https://img-blog.csdnimg.cn/20200304144741793.png
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