这篇文章主要讲解了Spring中的bean相关的生命周期，内容清晰明了，对此有兴趣的小伙伴可以学习一下，相信大家阅读完之后会有帮助。

前言

记得以前的时候，每次提起Spring中的bean相关的生命周期时，内心都无比的恐惧，因为好像有很多，自己又理不清楚：什么beanFactory啊，aware接口啊，beanPostProcessor啊，afterPropertiesSet啊，initMethod啊等等。

今天终于理清这些关系了，并且又新增了对postConstruct和lifecycle的理解。

执行顺序

- 首先是 BeanFactoryPostProcessor，它是针对所有bean的definition的，只执行一次

下面是针对每个bean的初始

- 实现了一系列aware接口的，比如BeanNameAware，ApplicationContextAware，调用其set方法- 执行BeanPostProcessor的postProcessBeforeInitialization方法- 带有@PostConstruct注解的方法- 实现InitializingBean接口的afterPropertiesSet方法- 指定的initMethod方法- 执行BeanPostProcessor的postProcessAfterInitialization方法- 实现了SmartLifecycle接口的start方法(实现Lifecycle接口的不会自动调用，需要显式的调用start方法)

下面是针对每个bean的销毁

- 实现了SmartLifecycle接口的stop方法(实现Lifecycle接口的不会自动调用，需要显式的调用stop方法)- 带有@PreDestroy注解的方法- 实现DisposableBean接口的destroy方法- 指定的destroyMethod方法

目前就想到这么多了，其他的麻烦在评论区留言呀~

代码实例

bean实体类

/** * @date: 2020-07-22 * * 一个简单的枚举类 */public enum BeanType { NORMAL, LIFECYCLE, SMART_LIFECYCLE;}import javax.annotation.PostConstruct;import javax.annotation.PreDestroy;import lombok.extern.slf4j.Slf4j;import org.springframework.beans.BeansException;import org.springframework.beans.factory.BeanNameAware;import org.springframework.beans.factory.DisposableBean;import org.springframework.beans.factory.InitializingBean;import org.springframework.context.ApplicationContext;import org.springframework.context.ApplicationContextAware;/** * @author: lihui * @date: 2020-07-22 * 一个简单的bean */@Slf4jpublic class NormalBean implements BeanNameAware, ApplicationContextAware, InitializingBean, DisposableBean { private BeanType beanType; public NormalBean() { this(BeanType.NORMAL); } public NormalBean(BeanType beanType) { this.beanType = beanType; } @PostConstruct public void postConstruct() { log.info("{}, postConstruct", beanType); } @Override public void afterPropertiesSet() throws Exception { log.info("{}, afterPropertiesSet", beanType); } public void initMethod() { log.info("{}, initMethod", beanType); } @PreDestroy public void preDestroy() { log.info("{}, preDestroy", beanType); } @Override public void destroy() throws Exception { log.info("{}, destroy", beanType); } public void destroyMethod() { log.info("{}, destroyMethod", beanType); } @Override public void setApplicationContext(ApplicationContext applicationContext) throws BeansException { log.info("setApplicationContext, applicationContext : {}", applicationContext); } @Override public void setBeanName(String name) { log.info("setBeanName, bean name : {}", name); }}import lombok.extern.slf4j.Slf4j;import org.springframework.context.Lifecycle;/** * @author: lihui * @date: 2020-07-22 * 实现了Lifecycle的一个bean */@Slf4jpublic class LifecycleBean extends NormalBean implements Lifecycle { private volatile boolean running = false; public LifecycleBean() { super(BeanType.LIFECYCLE); } @Override public void start() { log.info("start"); running = true; } @Override public void stop() { log.info("stop"); running = false; } @Override public boolean isRunning() { return running; }}import lombok.extern.slf4j.Slf4j;import org.springframework.context.SmartLifecycle;/** * @author: lihui * @date: 2020-07-22 * 实现了SmartLifecycle的一个bean */@Slf4jpublic class SmartLifecycleBean extends NormalBean implements SmartLifecycle { private volatile boolean running = false; public SmartLifecycleBean() { super(BeanType.SMART_LIFECYCLE); } @Override public void start() { log.info("start"); running = true; } @Override public void stop() { log.info("stop"); running = false; } @Override public boolean isRunning() { return running; }}

配置类

import lombok.extern.slf4j.Slf4j;import org.springframework.beans.BeansException;import org.springframework.beans.factory.config.BeanFactoryPostProcessor;import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;/** * @author: lihui * @date: 2020-07-25 */@Slf4jpublic class MyBeanFactoryPostProcessor implements BeanFactoryPostProcessor { @Override public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException { log.info("postProcessBeanFactory, beanFactory:{}", beanFactory); }}import lombok.extern.slf4j.Slf4j;import org.springframework.beans.BeansException;import org.springframework.beans.factory.config.BeanPostProcessor;/** * @author: lihui * @date: 2020-07-25 */@Slf4jpublic class MyBeanPostProcessor implements BeanPostProcessor { @Override public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException { log.info("postProcessBeforeInitialization, bean:{}", beanName); return bean; } @Override public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException { log.info("postProcessAfterInitialization, bean:{}", beanName); return bean; }}import lombok.extern.slf4j.Slf4j;import org.springframework.context.SmartLifecycle;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.Configuration;/** * @author: lihui * @date: 2020-07-22 */@Configuration@Slf4jpublic class Config { @Bean(initMethod = "initMethod", destroyMethod = "destroyMethod") public NormalBean normalBean() { return new NormalBean(); } @Bean(initMethod = "initMethod", destroyMethod = "destroyMethod") public LifecycleBean lifecycleBean() { return new LifecycleBean(); } @Bean(initMethod = "initMethod", destroyMethod = "destroyMethod") public SmartLifecycle smartLifecycle() { return new SmartLifecycleBean(); } @Bean public static MyBeanFactoryPostProcessor myBeanFactoryPostProcessor() { return new MyBeanFactoryPostProcessor(); } @Bean public static MyBeanPostProcessor myBeanPostProcessor() { return new MyBeanPostProcessor(); }}

Main类

import lombok.extern.slf4j.Slf4j;import org.springframework.context.ConfigurableApplicationContext;import org.springframework.context.annotation.AnnotationConfigApplicationContext;/** * @author: lihui * @date: 2020-07-22 */@Slf4jpublic class Main { public static void main(String[] args) throws InterruptedException { ConfigurableApplicationContext ctx = new AnnotationConfigApplicationContext(Config.class); ctx.registerShutdownHook(); Thread.sleep(5000); log.info("line ----------------------------- line"); ctx.start(); ctx.stop(); log.info("line ----------------------------- line"); }}

结果说明

结果正如前面所说的执行顺序一致，主要注意的就是Lifecycle接口和SmartLifecycle接口，只有实现了SmartLifecycle接口的bean在初始化时才会被自动调用，而实现了Lifecycle接口的除非显式调用start和stop方法才会被调用。

看完上述内容，是不是对Spring中的bean相关的生命周期有进一步的了解，如果还想学习更多内容，欢迎关注亿速云行业资讯频道。