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這篇文章主要講解了Spring中的bean相關的生命周期，內容清晰明了，對此有興趣的小伙伴可以學習一下，相信大家閱讀完之后會有幫助。
前言
記得以前的時候，每次提起Spring中的bean相關的生命周期時，內心都無比的恐懼，因為好像有很多，自己又理不清楚：什么beanFactory啊，aware接口啊，beanPostProcessor啊，afterPropertiesSet啊，initMethod啊等等。
今天終于理清這些關系了，并且又新增了對postConstruct和lifecycle的理解。
執行順序
- 首先是 BeanFactoryPostProcessor，它是針對所有bean的definition的，只執行一次
下面是針對每個bean的初始
下面是針對每個bean的銷毀
目前就想到這么多了，其他的麻煩在評論區留言呀~
代碼實例
bean實體類
/**
* @date: 2020-07-22
*
* 一個簡單的枚舉類
*/
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
* 一個簡單的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
* 實現了Lifecycle的一個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
* 實現了SmartLifecycle的一個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;
}
}配置類
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類
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");
}
}結果說明
結果正如前面所說的執行順序一致，主要注意的就是Lifecycle接口和SmartLifecycle接口，只有實現了SmartLifecycle接口的bean在初始化時才會被自動調用，而實現了Lifecycle接口的除非顯式調用start和stop方法才會被調用。
看完上述內容，是不是對Spring中的bean相關的生命周期有進一步的了解，如果還想學習更多內容，歡迎關注億速云行業資訊頻道。
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