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

/**
* @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
*/
@Slf4j
public 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
*/
@Slf4j
public 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
*/
@Slf4j
public 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
*/
@Slf4j
public 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
*/
@Slf4j
public 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
@Slf4j
public 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
*/
@Slf4j
public 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。