Spring Boot框架核心方法refresh

本文轉載自查看原文 2020-02-26 20:05 872 S.Spring Boot

refresh方法介紹

bean配置讀取和加載入口

在這個方法內完成sping框架啟動流程

首先從SpringBoot的啟動run方法，進入到AbstractApplicationContext類refresh方式涉及到下面多個子方法的調用

	@Override
	public void refresh() throws BeansException, IllegalStateException {
		synchronized (this.startupShutdownMonitor) {
			// Prepare this context for refreshing.
			prepareRefresh();

			// Tell the subclass to refresh the internal bean factory.
			ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();

			// Prepare the bean factory for use in this context.
			prepareBeanFactory(beanFactory);

			try {
				// Allows post-processing of the bean factory in context subclasses.
				postProcessBeanFactory(beanFactory);

				// Invoke factory processors registered as beans in the context.
				invokeBeanFactoryPostProcessors(beanFactory);

				// Register bean processors that intercept bean creation.
				registerBeanPostProcessors(beanFactory);

				// Initialize message source for this context.
				initMessageSource();

				// Initialize event multicaster for this context.
				initApplicationEventMulticaster();

				// Initialize other special beans in specific context subclasses.
				onRefresh();

				// Check for listener beans and register them.
				registerListeners();

				// Instantiate all remaining (non-lazy-init) singletons.
				finishBeanFactoryInitialization(beanFactory);

				// Last step: publish corresponding event.
				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();
			}
		}
	}

1、prepareRefresh();

容器狀態設置

初始化屬性設置

檢查必備屬性是否存在

2、obtainFreshBeanFactory

設置beanFactory序列化id

獲取beanFactory

3、prepareBeanFactory(beanFactory);

設置beanFactory一些屬性

添加后置處理器

設置忽略的自動裝配接口

注冊一些主件

4、postProcessBeanFactory(beanFactory);

子類重寫以在BeanFactory完成創建后做進一步設置

5、invokeBeanFactoryPostProcessors(beanFactory);

調用BeanDefinitionRegistryPostProcessor實現向容器內添加bean的定義（使用參考：實現BeanDefinitionRegistryPostProcessor）

調用BeanFactoryPostProcessor實現向容器內添加bean的定義添加屬性

BeanFactoryPostProcessor的使用

1)創建Teacher類

@Component
public class Teacher {

    private String name;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

2）創建類MyBeanFactoryPostProcessor ，實現BeanFactoryPostProcessor接口。並且給teacher增加name屬性值為Nick

@Component
public class MyBeanFactoryPostProcessor  implements BeanFactoryPostProcessor{
    @Override
    public void postProcessBeanFactory(ConfigurableListableBeanFactory configurableListableBeanFactory) throws BeansException {
        BeanDefinition teacher = configurableListableBeanFactory.getBeanDefinition("teacher");
        MutablePropertyValues propertyValues = teacher.getPropertyValues();
        propertyValues.addPropertyValue("name","Nick");
    }
}

3）運行測試方法testTeacher