springboot bean对象生命周期

Bean对象生命周期

Bean对象的生命周期主要由3部分组成：bean对象的初始化过程，bean对象在ioc容器中被使用，bean对象的销毁过程，具体可见下图：

初始化bean对象过程

方法	描述
bean对象实例化	调用构造函数为对象分配内存空间
setBeanName方法调用	如果对象实现了BeanNameAware接口，则调用该方法
setBeanFactory方法调用	如果对象实现了BeanFactoryAware接口，则调用该方法
setApplicationContext方法调用	如果实现了ApplicationContextAware接口，且spring ioc容器也是ApplicationContext的接口实现类，则调用该方法
postProcessBeforeInitialization方法调用	如果实现了BeanPostProcessor接口，则调用该方法
postConstruct注解方法调用	如果bean对象定义了@PostConstruct注解的方法，则调用该方法
afterPropertiesSet方法调用	如果实现了InitializingBean接口，则调用该方法
自定义init-method方法调用	如果设置了自定义初始化方法，则调用自定义初始化方法
postProcessAfterInitialization方法调用	如果实现了BeanPostProcessor接口，则调用该方法

销毁bean对象过程

方法	描述
PreDestroy注解方法调用	如果bean对象定义了@PreDestroy注解的方法，则调用该方法
destory方法调用	如果实现了DisposableBean接口，则调用该方法
自定义destroyMethod方法调用	如果自定义了销毁方法，则调用该方法

代码实例

下面的代码定义了一个bean类SpringLifeCycleBean用来对bean对象的生命周期进行测试，将上述不同阶段的方法都封装在该类中。

package com.mary;

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.BeanFactoryAware;
import org.springframework.beans.factory.BeanNameAware;
import org.springframework.beans.factory.DisposableBean;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.config.BeanPostProcessor;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.stereotype.Component;

import javax.annotation.PostConstruct;
import javax.annotation.PreDestroy;

/**
 * Created by gaoling on 2020/10/10.
 */
public class SpringLifeCycleBean implements BeanNameAware, BeanFactoryAware, ApplicationContextAware, BeanPostProcessor, DisposableBean{

    public SpringLifeCycleBean(){
        System.out.println("Constructor method invoked");
    }


    @Override
    public void setBeanName(String s) {
        System.out.println("BeanNameAware setBeanName method inovked, name: " + s);
    }


    @Override
    public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
        System.out.println("BeanFactoryAware setBeanFactory method inovked, beanFactory: " + beanFactory.getClass().getName());
    }


    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        System.out.println("ApplicationContextAware setApplicationContext method inovked, applicationContext: " + applicationContext.getClass().getName());
    }

    @Override
    public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
        System.out.println("BeanPostProcessor postProcessBeforeInitialization method inovked, beanName: " + beanName);
        return null;
    }

    @Override
    public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
        System.out.println("BeanPostProcessor postProcessAfterInitialization method inovked, beanName: " + beanName);
        return null;
    }

    @PostConstruct
    public void init(){
        System.out.println("PostConstruct method invoked");
    }

    @PreDestroy
    public void preDestroy(){
        System.out.println("PreDestroy method invoked");
    }

    @Override
    public void destroy() throws Exception {
        System.out.println("DisposableBean destroy method invoked");
    }

    public void customInit(){
        System.out.println("customInit method invoked");
    }

    public void customDestroy(){
        System.out.println("customDestroy method invoked");
    }
}


package com.mary;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;

/**
 * Created by gaoling on 2020/10/10.
 */
@SpringBootApplication
public class AppStarter {

    public static void main(String[] args){
        SpringApplication.run(AppStarter.class, args);
    }

    @Bean(destroyMethod = "customDestroy", initMethod = "customInit")
    public SpringLifeCycleBean lifeCycleBean(){
        SpringLifeCycleBean lifeCycleBean = new SpringLifeCycleBean();
        return lifeCycleBean;
    }
}

代码执行结果如下

Constructor method invoked
BeanPostProcessors (for example: not eligible for auto-proxying)
BeanNameAware setBeanName method inovked, name: lifeCycleBean
BeanFactoryAware setBeanFactory method inovked, beanFactory: org.springframework.beans.factory.support.DefaultListableBeanFactory
ApplicationContextAware setApplicationContext method inovked, applicationContext: org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext
PostConstruct method invoked
InitializingBean  afterPropertiesSet method invoked
customInit method invoked
BeanPostProcessor postProcessBeforeInitialization method inovked, beanName: org.springframework.boot.autoconfigure.web.servlet.ServletWebServerFactoryConfiguration$EmbeddedTomcat
BeanPostProcessor postProcessAfterInitialization method inovked, beanName: org.springframework.boot.autoconfigure.web.servlet.ServletWebServerFactoryConfiguration$EmbeddedTomcat