Spring Boot框架核心方法refresh

Posted 2021-03-07 work hard work smart

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refresh方法介绍

bean配置读取和加载入口

在这个方法内完成sping框架启动流程

首先从SpringBoot的启动run方法，进入到AbstractApplicationContext类refresh方式涉及到下面多个子方法的调用

	@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();

容器状态设置

初始化属性设置

检查必备属性是否存在

2、obtainFreshBeanFactory

设置beanFactory序列化id

获取beanFactory

3、prepareBeanFactory(beanFactory);

设置beanFactory一些属性

添加后置处理器

设置忽略的自动装配接口

注册一些主件

4、postProcessBeanFactory(beanFactory);

子类重写以在BeanFactory完成创建后做进一步设置

5、invokeBeanFactoryPostProcessors(beanFactory);

调用BeanDefinitionRegistryPostProcessor实现向容器内添加bean的定义（使用参考：实现BeanDefinitionRegistryPostProcessor）

调用BeanFactoryPostProcessor实现向容器内添加bean的定义添加属性

BeanFactoryPostProcessor的使用

1)创建Teacher类

@Component
public class Teacher {

    private String name;

    public String getName() {
        return name;
    }

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

2）创建类MyBeanFactoryPostProcessor ，实现BeanFactoryPostProcessor接口。并且给teacher增加name属性值为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）运行测试方法testTeacher