2023-01-04

springAOP和bean生命周期

文章目录

1. 从注解开始说
2. 从SpringBoot.run()说
3. postProcessBeanFactory()
4. invokeBeanFactoryPostProcessors()
5. onRefresh();

Springboot是Spring的脚手架,提供的自动配置功能初始化spring的ioc容器,

BeanDefinition:可以理解为定义bean

bean的生命周期,大部分初始化和赋值在AbstractAutowireCapableBeanFactory.doCreateBean 下来定义的:

- 创建bean
- 赋值和变量
- 初始化bean 包括 BeanPostProcessor,initMethod等
- AOP相关的内容
- 被销毁

/assets/images/bean/instantation.jpg

SpringApplicationContext:Spring的容器负责放置初始化好的bean

SpringFactoriesLoader 加载 spring.factories

1．生成一个SpringApplication的对象

1． webApplicationType ＝推测web应用类型（NONE、REACTIVE、SERVLET）
2．从spring．factories中获取BootstrapRegistryInitializer对象
3． initializers ＝从spring．factories中获取ApplicationContextInitializer对象
4． listeners ＝从spring．factories中获取ApplicationListener对象

2． SpringApplication的对象．run（）

1．获取SpringApplicationRunListener—-＞EventPublishingRunListener
\2. SpringApplicationRunListener.starting()
3．创建一个Spring容器
4． ApplicationContextInitializer—＞初始化Spring容器
\5. SpringApplicationRunListener.contextPrepared()
6．把传给run方法的配置类注册成为一个Bean
\7. SpringApplicationRunListener.contextLoaded()
8．会解析配置类、扫描、启动Tomcat／Jetty／Undertow
(AutoConfigurationImportSelector,DeferredImportSelector)
\9. SpringApplicationRunListener.started() I
10.
\10. SpringApplicationRunListener.ready()

从注解开始说

@enableSpringAutoConfig ->Configeration ->inportSelector-> AutoConfigurationImportSelector

@SpringBootConfig- mapperScan

@ComponentScan

autoConfigerationSelector.class 会解析 autoconfig包下面的bean.factory

从SpringBoot.run()说

SpringApplication.run()入口

AbstractApplicationContext.refresh()创建了ApplicationContext容器后刷新

DefaultListableBeanFactory,deGetBean() ApplicationContext集成了 ListableBeanFactory

DefaultSingletonBeanRgistry.getSingleton() 获取单例的bean实例

AbstractAutowireCapableBeanFactory.createBean();创建对应的bean对应上面的Bean的生命周期

newInstance() 初始化一个bean实例

在refresh()方法下对应的方法注释:

public void refresh() throws BeansException, IllegalStateException {
        synchronized (this.startupShutdownMonitor) {
            //1:准备刷新上下文环境
            prepareRefresh();

            //2:获取初始化Bean工厂
            ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();

            //3:对bean工厂进行填充属性
            prepareBeanFactory(beanFactory);

            try {
                //4:Spring开放接口 留给子类去实现该接口
                postProcessBeanFactory(beanFactory);

                //5:调用我们的bean工厂的后置处理器
                invokeBeanFactoryPostProcessors(beanFactory);

                //6:注册我们bean后置处理器 
                registerBeanPostProcessors(beanFactory);

                //7:初始化国际化资源处理器
                initMessageSource();

                //8:初始化事件多播器
                initApplicationEventMulticaster();

                //9:这个方法同样也是留个子类实现,其中springboot也是从这个方法进行tomcat的启动
                onRefresh();

                //10:把我们的事件监听器注册到多播器上
                registerListeners();

                //11:实例化所有的非懒加载的单实例bean
                finishBeanFactoryInitialization(beanFactory);

                //12:最后刷新容器 发布刷新事件(Spring cloud eureka也是从这里启动的)
                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();
            }
        }
    }

postProcessBeanFactory()

invokeBeanFactoryPostProcessors()


processConfigBeanDefinitions的调用逻辑
 读取所有的自动配置类(带有@Configuration注解的类)
 相当于加载beanDefination
 invokeBeanFactoryPostProcessors实现这两个接口可以定制
    - BeanDefinitionRegistry对象
    - ConfigurableListableBeanFactory对象。
    
    AbstractAutowireCapableBeanFactory.doCreateBean() 下的方法熟悉
    - populateBean()
    - initializeBean()
    - applyBeanPostProcessorsBeforeInitialization()
    		- processor.postProcessBeforeInitialization(result, beanName)
    			- invokeAwareInterfaces

onRefresh();

1	AbstractApplicationContext.onRefresh 是空但是AnnotationConfigServletWebServerApplicationContext是实际实现的类,下面有留言

/**

Create a new {@link AnnotationConfigServletWebServerApplicationContext} that needs

to be populated through {@link #register} calls and then manually
{@linkplain #refresh refreshed}.
*/
AnnotationConfigServletWebServerApplicationContext 继承了ServletWebServerApplicationContext 实现实现onRefresh的类是