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:

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