Spring的Bean的生命周期方法执行顺序测试

通过一个简单的Maven工程来演示Spring的Bean生命周期函数的执行顺序.

下面是工程的目录结构:

直接贴代码:

pom.xml文件内容:

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.xuebusi</groupId>
    <artifactId>spring-test</artifactId>
    <version>1.0-SNAPSHOT</version>

    <dependencies>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>4.3.12.RELEASE</version>
        </dependency>

        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>
    </dependencies>

</project>

beans.xml配置文件:

该配置文件主要用于演示init-method和destory-method两个方法的执行时机.

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">

    <context:component-scan base-package="com.xuebusi"></context:component-scan>
    <bean id="userService" class="com.xuebusi.service.UserService" init-method="init" destroy-method="destory"/>
</beans>

SpringBeanPostProcessor类:

这个类继承了InstantiationAwareBeanPostProcessorAdapter类,重写了它的一些和Bean的实例化以及初始化有关的生命周期方法.

但是这些方法是针对Spring容器中的所有Bean的,所以加了个if判断,因为这里只是演示userService这个Bean的生命周期.

import org.springframework.beans.BeansException;
import org.springframework.beans.PropertyValues;
import org.springframework.beans.factory.config.InstantiationAwareBeanPostProcessorAdapter;
import org.springframework.stereotype.Component;

import java.beans.PropertyDescriptor;

@Component
public class SpringBeanPostProcessor extends InstantiationAwareBeanPostProcessorAdapter {

    @Override
    public Object postProcessBeforeInstantiation(Class<?> beanClass, String beanName) throws BeansException {
        if ("userService".equals(beanName)) {
            System.out.println(">>>> postProcessBeforeInstantiation");
        }
        return super.postProcessBeforeInstantiation(beanClass, beanName);
    }

    @Override
    public boolean postProcessAfterInstantiation(Object bean, String beanName) throws BeansException {
        if ("userService".equals(beanName)) {
            System.out.println(">>>> postProcessAfterInstantiation");
        }
        return super.postProcessAfterInstantiation(bean, beanName);
    }

    @Override
    public PropertyValues postProcessPropertyValues(PropertyValues pvs, PropertyDescriptor[] pds, Object bean, String beanName) throws BeansException {
        if ("userService".equals(beanName)) {
            System.out.println(">>>> postProcessPropertyValues");
        }
        return super.postProcessPropertyValues(pvs, pds, bean, beanName);
    }

    @Override
    public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
        if ("userService".equals(beanName)) {
            System.out.println(">>>> postProcessBeforeInitialization");
        }
        return super.postProcessBeforeInitialization(bean, beanName);
    }

    @Override
    public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
        if ("userService".equals(beanName)) {
            System.out.println(">>>> postProcessAfterInitialization");
        }
        return super.postProcessAfterInitialization(bean, beanName);
    }
}

UserService类:

这就是要演示的Bean,让它实现Spring的InitializingBean接口来测试afterPropertiesSet方法, 实现BeanNameAware接口来测试setBeanName方法,实现BeanFactoryAware接口来测试setBeanFactory方法.

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.InitializingBean;
import org.springframework.stereotype.Service;

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

@Service
public class UserService implements InitializingBean, BeanNameAware, BeanFactoryAware {

    private String userName;

    public UserService() {
        System.out.println(">>>> UserService");
    }

    public String getUserName() {
        return userName;
    }

    public void setUserName(String userName) {
        this.userName = userName;
    }

    @PostConstruct
    public void postConstruct() {
        System.out.println(">>>> postConstruct");
    }

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

    public void init() {
        System.out.println(">>>> init");
    }

    public void destory() {
        System.out.println(">>>> destory");
    }

    public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
        System.out.println(">>>> setBeanFactory");
    }

    public void setBeanName(String s) {
        System.out.println(">>>> setBeanName");
    }

    public void afterPropertiesSet() throws Exception {
        System.out.println(">>>> afterPropertiesSet");
    }
}

AppTest类:

该类通过junit测试方法来启动一个Spring容器,并从容器中获取userService这个Bean对象.最后调用close方法销毁Spring容器.

import com.xuebusi.service.UserService;
import org.junit.Test;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class AppTest {

    @Test
    public void run() {
        ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("beans.xml");
        UserService userService = context.getBean("userService", UserService.class);
        userService.setUserName("苍井空");
        String userName = userService.getUserName();
        System.out.println(userName);
        context.close();
    }
}

 运行AppTest的测试方法run()然后观察控制台,日志展示出了"userService"这个Bean的生命周期函数执行顺序:

>>>> postProcessBeforeInstantiation
>>>> UserService
>>>> postProcessAfterInstantiation
>>>> postProcessPropertyValues
>>>> setBeanName
>>>> setBeanFactory
>>>> postProcessBeforeInitialization
>>>> postConstruct
>>>> afterPropertiesSet
>>>> init
>>>> postProcessAfterInitialization
苍井空
>>>> preDestroy
>>>> destory

总结一个Bean的生命周期方法执行顺序:

1. 实例化前                postProcessBeforeInstantiation()
2. 构造方法                构造方法
3. 实例化后                postProcessAfterInstantiation()
4. 设置属性                postProcessProperties()
5. 设置Bean名称            setBeanName()
6. 设置BeanFactory        setBeanFactory()
7. 初始化前                postProcessBeforeInitialization()
8. 构造之后                加了 @PostConstruct 的方法
9. 所有属性赋值之后         afterPropertiesSet()
10.初始化方法              配置文件中指定的 init-method 方法
10.初始化后                postProcessAfterInitialization()
11.销毁之前                加了 @PreDestroy 的方法
12.销毁方法                配置文件中指定的 destroy-method 方法