SpringBean生命周期详解
SpringBean生命周期详解
一、简述：
Spring是我们每天都在使用的框架，Bean是被Spring管理的Java对象，是Spring框架最重要的部分之一，那么让我们一起了解一下Spring中Bean的生命周期是怎样的吧
二、流程图
总体分为四个阶段：
①实例化 CreateBeanInstance
②属性赋值 PopulateBean
③初始化 Initialization
④销毁 Destruction**
其中多个增强接口贯穿了这四个阶段！
三、SpringBean生命周期中的增强接口PostProcessor：
在上图里有多种后置处理器接口，它们贯穿了Bean的生命周期，且它们的实现类都会在SpringIOC容器进行初始化的时候进行实例化，让我们来做一个区分：
解释：
Bean的实例化：
是指Spring通过反射获取Bean的构造方法进行实例化的过程
Bean的初始化：
是指Bean的属性赋值、执行初始化方法（init-method）的过程
四、实例展示
SpringBeanDemo
package com.rx.spring;
import com.rx.spring.domain.Person;
import com.rx.spring.domain.Student;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
public class SpringBeanDemo {
public static void main(String[] args) throws Exception {
System.out.println("****开始启动****");
AnnotationConfigApplicationContext applicationContext = new AnnotationConfigApplicationContext(Config.class);
System.out.println("****启动完毕****");
Person person = applicationContext.getBean("person", Person.class);
Student student = applicationContext.getBean("student", Student.class);
System.out.println("=============================================");
System.out.println("person：" + person);
System.out.println("student：" + student);
person.destroy();
System.out.println("============现在开始关闭容器======================");
applicationContext.registerShutdownHook();
}
}
Config
package com.rx.spring;
import org.springframework.context.annotation.*;
@Configuration
@ComponentScan("com.rx.spring")
@ImportResource("classpath:spring.xml")
public class Config {
}
Person
package com.rx.spring.domain;
import lombok.Data;
import org.springframework.beans.factory.DisposableBean;
@Data
public class Person implements DisposableBean {
private String name;
private String address;
private String tel;
public Person(String name, String address, String tel) {
System.out.println("Person--->>>有参构造方法");
this.name = name;
this.address = address;
this.tel = tel;
}
public Person() {
System.out.println("Person--->>>无参构造方法");
}
private void raoInitMethod() {
System.out.println("person--->>>InitMethod...");
}
private void raoDestroyMethod() {
System.out.println("person--->>>DestroyMethod...");
}
@Override
public void destroy() throws Exception {
System.out.println("【DisposableBean接口】调用DisposableBean.destroy()");
}
}
Student
package com.rx.spring.domain;
import lombok.Data;
import org.springframework.beans.factory.DisposableBean;
@Data
public class Student implements DisposableBean {
private String username;
private String password;
public Student(String username, String password) {
System.out.println("student--->>有参构造方法");
this.username = username;
this.password = password;
}
public Student() {
System.out.println("student--->>>无参构造方法");
}
private void raoInitMethod() {
System.out.println("student--->>>InitMethod...");
}
private void raoDestroyMethod() {
System.out.println("student--->>>DestroyMethod...");
}
@Override
public void destroy() throws Exception {
System.out.println("【DisposableBean接口】调用DisposableBean.destroy()");
}
}
RaoBeanFactoryPostProcessor
package com.rx.spring.beanfactorypostprocessor;
import org.springframework.beans.BeansException;
import org.springframework.beans.MutablePropertyValues;
import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.beans.factory.config.BeanFactoryPostProcessor;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.stereotype.Component;
@Component
public class RaoBeanFactoryPostProcessor implements BeanFactoryPostProcessor {
@Override
public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
System.out.println("postProcessBeanFactory...");
String[] beanStr = beanFactory.getBeanDefinitionNames();
for (String beanName : beanStr) {
if ("person".equals(beanName)) {
BeanDefinition beanDefinition = beanFactory.getBeanDefinition(beanName);
MutablePropertyValues m = beanDefinition.getPropertyValues();
if (m.contains("address")) {
//这个方法是判断是否有propertyName=username，有就替换，没有就添加
m.addPropertyValue("address", "大兴区");
System.out.println("***修改了address属性初始值了***");
}
}
}
}
}
RaoInstantiationAwareBeanPostProcessor
package com.rx.spring.beanpostprocessor;
import com.rx.spring.domain.Person;
import org.springframework.beans.BeansException;
import org.springframework.beans.PropertyValue;
import org.springframework.beans.PropertyValues;
import org.springframework.beans.factory.config.InstantiationAwareBeanPostProcessorAdapter;
import org.springframework.stereotype.Component;
@Component
public class RaoInstantiationAwareBeanPostProcessor extends InstantiationAwareBeanPostProcessorAdapter {
@Override
public Object postProcessBeforeInstantiation(Class<?> beanClass, String beanName) throws BeansException {
if ("person".equals(beanName) || "student".equals(beanName)) {
System.out.println(beanName + "--->>>InstantiationAwareBeanPostProcessor.postProcessBeforeInstantiation....");
}
return null;
}
@Override
public boolean postProcessAfterInstantiation(Object bean, String beanName) throws BeansException {
if ("person".equals(beanName) || "student".equals(beanName)) {
System.out.println(beanName + "--->>>InstantiationAwareBeanPostProcessor.postProcessAfterInstantiation....");
}
return bean instanceof Person;
}
@Override
public PropertyValues postProcessProperties(PropertyValues pvs, Object bean, String beanName) throws BeansException {
System.out.println(beanName + "--->>>InstantiationAwareBeanPostProcessor.postProcessProperties...");
PropertyValue[] propertyValues = pvs.getPropertyValues();
for (PropertyValue propertyValue : propertyValues) {
if ("name".equals(propertyValue.getName())) {
propertyValue.setConvertedValue("改后rx");
}
}
return pvs;
}
}
RaoBeanPostProcessor
package com.rx.spring.beanpostprocessor;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanPostProcessor;
import org.springframework.stereotype.Component;
@Component
public class RaoBeanPostProcessor implements BeanPostProcessor {
@Override
public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
if ("person".equals(beanName) || "student".equals(beanName)) {
System.out.println(beanName + "--->>>BeanPostProcessor.postProcessBeforeInitialization...");
}
return bean;
}
@Override
public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
if ("person".equals(beanName) || "student".equals(beanName)) {
System.out.println(beanName + "--->>>BeanPostProcessor.postProcessAfterInitialization....");
}
return bean;
}
}
spring.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
<bean id ="person" class="com.rx.spring.domain.Person" init-method="raoInitMethod" destroy-method="raoDestroyMethod">
<property name="name" value="rx"/>
<property name="address" value="beijing"/>
<property name="tel" value="157********"/>
</bean>
<bean id ="student" class="com.rx.spring.domain.Student" init-method="raoInitMethod" destroy-method="raoDestroyMethod">
<property name="username" value="rx"/>
<property name="password" value="1234"/>
</bean>
</beans>
运行结果：
运行结果符合预期，成功验证了之前的结论！！！