Spring Bean's life

Spring Bean's life

When you work directly in Java, you can do anything you like with your objects and do not always need to rely on the container lifecycle.

Preface:

Bean corresponding instantiated and not immediately after the start Ioc container, when the container only has all Ioc objectsBeanDefinition(Bean对象在Spring中的描述,包含该Bean在容器中实例化所需的信息，通过解析xml/javaconfig后所得)

Spring Bean Life Cycle Management

Spring bean factoryTo manage Beansthe life cycle, by implementing InitializingBean and DisposableBean

These two interfaces only one way we can declare 初始化/关闭resource in the bean

Of course, throughout the life cycle also provides some Call the Back Methods , these methods are similar to the Servletimplementations of the listener

• When Beanin post-initializationtime stage, we can achieve InitializingBeanto implement the interfaceafterPropertiesSet()
• When Beanin pre-destructiontime stage, we can implement DisposableBeaninterfaces to implement destroy()method

Spring Bean's life cycle chart

Code Time

In Rickclass to Spring container, a method for performing sequential order Spring container

Rick.java

public class Rick implements InitializingBean, DisposableBean {
    public Rick(){
        System.out.println("Rick is in [Rick] - Rick()");
    }

    public void customInit(){
        System.out.println("Rick is in [Rick] - customInit()");
    }

    @PostConstruct
    public void postConstruct(){
        System.out.println("Rick is in [@PostConstruct] - postConstruct()");
    }

    @Override
    public void afterPropertiesSet() throws Exception {
        System.out.println("Rick is in [InitializingBean] - afterPropertiesSet()");
    }

    @PreDestroy
    public void preDestroy(){
        System.out.println("Rick is in [@PreDestroy] - preDestroy()");
    }

    @Override
    public void destroy() throws Exception {
        System.out.println("Rick is in [DisposableBean] - destroy()");
    }

    public void customDestroy(){
        System.out.println("Rick is in [Rick] - customDestroy()");
    }
}

JoinBeanPostProcess

RickBeanPostProcess.java

public class RickBeanPostProcess implements BeanPostProcessor {
    @Override
    public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
        if (bean instanceof Rick) {
            System.out.println("Rick is in [BeanPostProcessor] - postProcessBeforeInitialization()");
        }

        return bean;
    }

    @Override
    public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
        if (bean instanceof Rick) {
            System.out.println("Rick is in [BeanPostProcessor] - postProcessAfterInitialization()");
        }
        return bean;
    }
}

Configuration class

RickConfig.java

@Configuration
public class RickConfig {

    /**
     * 指定自定义初始化方法和自定义销毁方法
     * @return Rick
     */
    @Bean(initMethod = "customInit",destroyMethod = "customDestroy")
    public Rick rick(){
        return new Rick();
    }

    @Bean
    public RickBeanPostProcess rickBeanPostProcess(){
        return new RickBeanPostProcess();
    }
}

Test category

Client.java

public class Client {
    public static void main(String[] args) {
        ApplicationContext applicationContext = new AnnotationConfigApplicationContext(RickConfig.class);
        ((AnnotationConfigApplicationContext) applicationContext).close();
    }
}

The final results were as follows

Rick is in [Rick] - Rick()
Rick is in [BeanPostProcessor] - postProcessBeforeInitialization()
Rick is in [@PostConstruct] - postConstruct()
Rick is in [InitializingBean] - afterPropertiesSet()
Rick is in [Rick] - customInit()
Rick is in [BeanPostProcessor] - postProcessAfterInitializa
Rick is in [@PreDestroy] - preDestroy()
Rick is in [DisposableBean] - destroy()
Rick is in [Rick] - customDestroy()

reference

Spring Framework Documentation

Spring Bean Life Cycle Explained

Spring Bean Life Cycle

Spring Boot Bean Lifecycle

Spring的Bean生命周期理解