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