spring容器refresh方法源码分析(二)

快来打我* 2022-12-27 11:19 175阅读 0赞

[spring容器refresh方法源码分析(一)][spring_refresh]接着前面讲:

### 文章目录 ###

*   *   *  registerBeanPostProcessors方法
         *  initMessageSource方法(不重要)
         *  initApplicationEventMulticaster初始化事件监听多路广播器(不重要)
         *  onRefresh 初始化子类的一些特殊的bean(在初始化单例bean之前)(不重要)
         *  registerListeners注册事件监听器

### registerBeanPostProcessors方法 ###

首先了解这个方法是注册BeanPostProcessor到spring容器,跟invokeBeanFactoryPostProcessors方法解析差不多,也可以通过PriorityOrdered,Ordered接口来调整优先级,不同的是invokeBeanFactoryPostProcessors会直接执行BeanFactoryPostProcessors的方法,而registerBeanPostProcessors仅仅是注册,BeanPostProcessors的两个方法,分别在spring创建bean的时候,执行初始化方法前,和在初始化方法后执行的:

public interface BeanPostProcessor { 
    
    	Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException;
    
    	Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException;
    
    }

源码:

protected void registerBeanPostProcessors(ConfigurableListableBeanFactory beanFactory) { 
    		PostProcessorRegistrationDelegate.registerBeanPostProcessors(beanFactory, this);
    	}
    
    
    public static void registerBeanPostProcessors(
    			ConfigurableListableBeanFactory beanFactory, AbstractApplicationContext applicationContext) { 
    
    		//找出所有BeanPostProcessor的实现类
    		String[] postProcessorNames = beanFactory.getBeanNamesForType(BeanPostProcessor.class, true, false);
    
    		// Register BeanPostProcessorChecker that logs an info message when
    		// a bean is created during BeanPostProcessor instantiation, i.e. when
    		// a bean is not eligible for getting processed by all BeanPostProcessors.
    		//BeanPostProcessor的计数
    		int beanProcessorTargetCount = beanFactory.getBeanPostProcessorCount() + 1 + postProcessorNames.length;
    		//添加BeanPostProcessorChecker到spring容器中(用于记录信息)
    		beanFactory.addBeanPostProcessor(new BeanPostProcessorChecker(beanFactory, beanProcessorTargetCount));
    
    		// Separate between BeanPostProcessors that implement PriorityOrdered,
    		// Ordered, and the rest.
    		//前面分析过BeanFactoryPostProcessor,进行加载的时候会区分实现接口PriorityOrdered跟Ordered接口和没有实现接口的类
    		//实现了PriorityOrdered接口的beanPostProcessor
    		List<BeanPostProcessor> priorityOrderedPostProcessors = new ArrayList<BeanPostProcessor>();
    		//spring容器的beanPostProcessor
    		List<BeanPostProcessor> internalPostProcessors = new ArrayList<BeanPostProcessor>();
    		//实现了Ordered接口的beanPostProcessor
    		List<String> orderedPostProcessorNames = new ArrayList<String>();
    		//普通beanPostProcessor的名称
    		List<String> nonOrderedPostProcessorNames = new ArrayList<String>();
    
    		//遍历所有beanPostProcessor,进行区分
    		for (String ppName : postProcessorNames) { 
    			// 实现了PriorityOrdered接口的BeanPostProcessor
    			if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) { 
    				//拿到对应的BeanPostProcessor添加到priorityOrderedPostProcessors中
    				BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
    				priorityOrderedPostProcessors.add(pp);
    				//如果也实现了MergedBeanDefinitionPostProcessor接口则添加到internalPostProcessors中
    				if (pp instanceof MergedBeanDefinitionPostProcessor) { 
    					internalPostProcessors.add(pp);
    				}
    			}
    			else if (beanFactory.isTypeMatch(ppName, Ordered.class)) { 
    				//实现Ordered接口,添加到orderedPostProcessorNames
    				orderedPostProcessorNames.add(ppName);
    			}
    			else { 
    				//未实现Ordered接口的
    				nonOrderedPostProcessorNames.add(ppName);
    			}
    		}
    
    		// First, register the BeanPostProcessors that implement PriorityOrdered.
    		//首先,对实现了PriorityOrdered的BeanPostProcessors进行排序,和注册
    		sortPostProcessors(priorityOrderedPostProcessors, beanFactory);
    		registerBeanPostProcessors(beanFactory, priorityOrderedPostProcessors);
    
    		// Next, register the BeanPostProcessors that implement Ordered.
    		//接下来注册实现Ordered接口的BeanPostProcessors
    		List<BeanPostProcessor> orderedPostProcessors = new ArrayList<BeanPostProcessor>();
    		for (String ppName : orderedPostProcessorNames) { 
    			BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
    			orderedPostProcessors.add(pp);
    			if (pp instanceof MergedBeanDefinitionPostProcessor) { 
    				// 如果ppName对应的Bean实例也实现了MergedBeanDefinitionPostProcessor接口,
    				// 则将ppName对应的Bean实例添加到internalPostProcessors
    				internalPostProcessors.add(pp);
    			}
    		}
    		sortPostProcessors(orderedPostProcessors, beanFactory);
    		registerBeanPostProcessors(beanFactory, orderedPostProcessors);
    
    		// Now, register all regular BeanPostProcessors.
    		//注册所有常规BeanPostProcessors
    		List<BeanPostProcessor> nonOrderedPostProcessors = new ArrayList<BeanPostProcessor>();
    		for (String ppName : nonOrderedPostProcessorNames) { 
    			BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
    			nonOrderedPostProcessors.add(pp);
    			if (pp instanceof MergedBeanDefinitionPostProcessor) { 
    				internalPostProcessors.add(pp);
    			}
    		}
    		registerBeanPostProcessors(beanFactory, nonOrderedPostProcessors);
    
    		// Finally, re-register all internal BeanPostProcessors.
    		//最后, 重新注册所有内部BeanPostProcessors（相当于内部的BeanPostProcessor(实现了MergedBeanDefinitionPostProcessor)会被移到处理器链的末尾）
    		sortPostProcessors(internalPostProcessors, beanFactory);
    		// 注册internalPostProcessors
    		registerBeanPostProcessors(beanFactory, internalPostProcessors);
    
    		// Re-register post-processor for detecting inner beans as ApplicationListeners,
    		// moving it to the end of the processor chain (for picking up proxies etc).
    		// 重新注册ApplicationListenerDetector,放到处理链的最后
    		beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(applicationContext));
    	}

### initMessageSource方法(不重要) ###

初始化当前 ApplicationContext 的 MessageSource，国际化等等;  
了解一下即可源码:

protected void initMessageSource() { 
    		ConfigurableListableBeanFactory beanFactory = getBeanFactory();
    		//先判断是否有名称为messageSource的对象
    		if (beanFactory.containsLocalBean(MESSAGE_SOURCE_BEAN_NAME)) { 
    			this.messageSource = beanFactory.getBean(MESSAGE_SOURCE_BEAN_NAME, MessageSource.class);
    			// Make MessageSource aware of parent MessageSource.
    			//当父类Bean工厂不为空，并且这个bean对象是HierarchicalMessageSource类型
    			if (this.parent != null && this.messageSource instanceof HierarchicalMessageSource) { 
    				HierarchicalMessageSource hms = (HierarchicalMessageSource) this.messageSource;
    				//设置父类MessageSource，此处设置内部的parent messageSource
    				if (hms.getParentMessageSource() == null) { 
    					// Only set parent context as parent MessageSource if no parent MessageSource
    					// registered already.
    					hms.setParentMessageSource(getInternalParentMessageSource());
    				}
    			}
    			if (logger.isDebugEnabled()) { 
    				logger.debug("Using MessageSource [" + this.messageSource + "]");
    			}
    		}
    		else { 
    			// Use empty MessageSource to be able to accept getMessage calls.
    			//如果没有xml文件定义信息源对象，新建DelegatingMessageSource类作为messageSource的Bean
    			//因为DelegatingMessageSource类实现了HierarchicalMessageSource接口，而这个接口继承了MessageSource这个类
    			//因此实现了这个接口的类，都是MessageSource的子类，因此DelegatingMessageSource也是一个MessageSource
    			DelegatingMessageSource dms = new DelegatingMessageSource();
    			//给这个DelegatingMessageSource添加父类消息源
    			dms.setParentMessageSource(getInternalParentMessageSource());
    			this.messageSource = dms;
    			//注册到工厂
    			beanFactory.registerSingleton(MESSAGE_SOURCE_BEAN_NAME, this.messageSource);
    			if (logger.isDebugEnabled()) { 
    				logger.debug("Unable to locate MessageSource with name '" + MESSAGE_SOURCE_BEAN_NAME +
    						"': using default [" + this.messageSource + "]");
    			}
    		}
    	}

### initApplicationEventMulticaster初始化事件监听多路广播器(不重要) ###

也没啥讲的,就是往spring容器中初始化多播器;用来处理事件的分发(如,spring容器启动完成事件):

protected void initApplicationEventMulticaster() { 
    		ConfigurableListableBeanFactory beanFactory = getBeanFactory();
    		//首先判断spring容器中是否有定义了id为aplicationEventMulticaster的bean对象
    		if (beanFactory.containsLocalBean(APPLICATION_EVENT_MULTICASTER_BEAN_NAME)) { 
    			this.applicationEventMulticaster =
    					beanFactory.getBean(APPLICATION_EVENT_MULTICASTER_BEAN_NAME, ApplicationEventMulticaster.class);
    			if (logger.isDebugEnabled()) { 
    				logger.debug("Using ApplicationEventMulticaster [" + this.applicationEventMulticaster + "]");
    			}
    		}
    		else { 
    			//没有就注册一个SimpleApplicationEventMulticaster
    			this.applicationEventMulticaster = new SimpleApplicationEventMulticaster(beanFactory);
    			beanFactory.registerSingleton(APPLICATION_EVENT_MULTICASTER_BEAN_NAME, this.applicationEventMulticaster);
    			if (logger.isDebugEnabled()) { 
    				logger.debug("Unable to locate ApplicationEventMulticaster with name '" +
    						APPLICATION_EVENT_MULTICASTER_BEAN_NAME +
    						"': using default [" + this.applicationEventMulticaster + "]");
    			}
    		}
    	}

### onRefresh 初始化子类的一些特殊的bean(在初始化单例bean之前)(不重要) ###

空方法,在具体子类中实现

### registerListeners注册事件监听器 ###

源码:

protected void registerListeners() { 
    		// Register statically specified listeners first.
    		// 首先注册配置的监听器,注册到广播器
    		for (ApplicationListener<?> listener : getApplicationListeners()) { 
    			getApplicationEventMulticaster().addApplicationListener(listener);
    		}
    
    		// Do not initialize FactoryBeans here: We need to leave all regular beans
    		// uninitialized to let post-processors apply to them!
    		// 获取所有的监听器的名称,设置到广播器
    		String[] listenerBeanNames = getBeanNamesForType(ApplicationListener.class, true, false);
    		for (String listenerBeanName : listenerBeanNames) { 
    			getApplicationEventMulticaster().addApplicationListenerBean(listenerBeanName);
    		}
    
    		// Publish early application events now that we finally have a multicaster...
    		// 发布早期应用事件
    		Set<ApplicationEvent> earlyEventsToProcess = this.earlyApplicationEvents;
    		this.earlyApplicationEvents = null;
    		if (earlyEventsToProcess != null) { 
    			for (ApplicationEvent earlyEvent : earlyEventsToProcess) { 
    				getApplicationEventMulticaster().multicastEvent(earlyEvent);
    			}
    		}
    	}

[spring_refresh]: https://yidajava.blog.csdn.net/article/details/110648494