springBean生命周期解析

本文基于Spring5.3.7

参考：
kykangyuky Spring中bean的生命周期
阿斌Java之路 SpringBean的生命周期，
杨开振 JavaEE互联网轻量级框架整合开发
黑马程序员 JavaEE企业级应用开发教程
马士兵 Spring源码讲解

一. SpringBean生命周期流程图

二. 示例代码

1. 定义果汁描述实体类

package com.xiaobai.spring_bean_life_cycle;import lombok.Data;
import lombok.extern.slf4j.Slf4j;/*** @author wangtw* @date 2023/6/24 16:38* @description 果汁描述实体类*/
@Slf4j
@Data
public class Source {public Source() {log.info("source实例化");}/*** 水果*/private String fruit;/*** 糖量*/private String sugar;/*** 大小*/private String size;
}

2. 定义果汁生成器

package com.xiaobai.spring_bean_life_cycle;import lombok.Data;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.*;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;/*** @author wangtw* @date 2023/6/24 16:28* @description 果汁生成器*/
@Slf4j
@Data
public class JuiceMaker implements BeanNameAware, BeanFactoryAware,ApplicationContextAware, InitializingBean, DisposableBean {public JuiceMaker(){log.info("juice实例化");}private String beverageShop;private Source source;/*** 自定义初始化方法*/public void init() {log.info("【{}】执行自定义初始化方法", this.getClass().getSimpleName());}/*** 自定义销毁方法*/public void myDestroy() {log.info("【{}】执行自定义销毁方法", this.getClass().getSimpleName());}public String makeJuice() {String juice = "这是一杯由" + beverageShop + "饮品店，提供的" + source.getSize() + source.getSugar() + source.getFruit();return juice;}@Overridepublic void setBeanFactory(BeanFactory beanFactory) throws BeansException {log.info("【{}】调用BeanFactoryAware接口的setBeanFactory方法", this.getClass().getSimpleName());}@Overridepublic void setBeanName(String s) {log.info("【{}】调用BeanNameAware接口的setBeanName方法", this.getClass().getSimpleName());}@Overridepublic void destroy() throws Exception {log.info("调用接口DisposableBean的destroy方法");}@Overridepublic void afterPropertiesSet() throws Exception {log.info("【{}】调用InitializingBean接口的afterPropertiesSet方法", this.getClass().getSimpleName());}@Overridepublic void setApplicationContext(ApplicationContext applicationContext) throws BeansException {log.info("【{}】调用ApplicationContextAware接口的setApplicationContext方法", this.getClass().getSimpleName());}
}

3. 定义Bean实现BeanPostProcessor接口

package com.xiaobai.spring_bean_life_cycle;import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanPostProcessor;
import org.springframework.context.annotation.Bean;
import org.springframework.stereotype.Component;/*** @author wangtw* @date 2023/6/24 16:07* @description*/
@Slf4j
public class BeanPostProcessorImpl implements BeanPostProcessor {@Overridepublic Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {log.info("【{}】对象{}预初始化开始", bean.getClass().getSimpleName(), beanName);return bean;}@Overridepublic Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {log.info("【{}】对象{}预初始化完成", bean.getClass().getSimpleName(), beanName);return bean;}
}

4. 定义SpringBean配置类

package com.xiaobai.spring_bean_life_cycle;import org.springframework.beans.factory.config.BeanPostProcessor;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;/*** @author wangtw* @date 2023/6/25 10:33* @description Spring配置类*/
@Configuration
public class LifeConfiguration {@Bean("beanPostProcessor")public BeanPostProcessor beanPostProcessor() {return new BeanPostProcessorImpl();}@Bean("source")public Source source() {Source source = new Source();source.setFruit("橙汁");source.setSugar("少糖");source.setSize("大杯");return source;}@Bean(value = "juiceMaker", initMethod = "init", destroyMethod = "myDestroy")public JuiceMaker juiceMaker() {JuiceMaker juiceMaker = new JuiceMaker();juiceMaker.setSource(source());juiceMaker.setBeverageShop("贡茶");return juiceMaker;}
}

5. 测试类及输出结果

package com.xiaobai.spring_bean_life_cycle;import lombok.extern.slf4j.Slf4j;
import org.junit.jupiter.api.Test;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;/*** @author wangtw* @date 2023/6/25 10:40* @description springBean生命周期测试类*/
@Slf4j
public class SpringBeanLifeTest {@Testpublic void testLifeCycle() {ConfigurableApplicationContext context = new AnnotationConfigApplicationContext(LifeConfiguration.class);JuiceMaker juiceMaker = (JuiceMaker) context.getBean("juiceMaker");log.info(juiceMaker.makeJuice());context.close();}
}

三. 源码解析

（一）Bean实例化

1. 根据注解加载Bean

org.springframework.beans.factory.config.BeanFactoryPostProcessor
org.springframework.context.annotation.ConfigurationClassPostProcessor#processConfigBeanDefinitions
org.springframework.context.annotation.ConfigurationClassParser#parse(java.util.Set<org.springframework.beans.factory.config.BeanDefinitionHolder>)
org.springframework.context.annotation.ConfigurationClassParser#parse(org.springframework.core.type.AnnotationMetadata, java.lang.String)
org.springframework.context.annotation.ConfigurationClassParser#processConfigurationClass
org.springframework.context.annotation.ConfigurationClassParser#doProcessConfigurationClass

2. 在SpringBean实例化前会把扫描到的类加载到BeanDefinition中，然后将BeanDefinition中的信息注册到Spring容器中

org.springframework.context.annotation.AnnotationConfigApplicationContext#AnnotationConfigApplicationContext()
org.springframework.context.annotation.AnnotationConfigApplicationContext#register
org.springframework.context.annotation.AnnotatedBeanDefinitionReader#doRegisterBean
org.springframework.beans.factory.support.BeanDefinitionRegistry#registerBeanDefinition

3. 完成了BeanDefinition注册后，对Bean进行实例化

org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory#createBeanInstance

（二）初始化

1. 属性赋值

（1）自定义对象属性赋值

org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory#populateBean

（2）容器对象赋值：检查aware接口并设置相关依赖（aware接口用于标记，判断调用什么方法）

org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory#invokeAwareMethods

2. 执行前置处理方法

org.springframework.beans.factory.config.BeanPostProcessor#postProcessBeforeInitialization

3. 执行初始化方法

（1）检测Bean是否实现了InitializingBean接口

org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory#invokeInitMethods

（2）调用afterPropertiesSet方法

org.springframework.beans.factory.InitializingBean#afterPropertiesSet

（3）调用自定义初始化方法

org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory#invokeCustomInitMethod

4. 执行后置处理方法

org.springframework.aop.framework.autoproxy.AbstractAutoProxyCreator#postProcessAfterInitialization
org.springframework.aop.framework.autoproxy.AbstractAutoProxyCreator#wrapIfNecessary

创建代理对象
org.springframework.aop.framework.autoproxy.AbstractAutoProxyCreator#createProxy
org.springframework.aop.framework.AopProxy#getProxy(java.lang.ClassLoader)

（三）使用

（四）销毁