Spring（三）--Spring bean的生命周期

时间：2023-11-30 21:49:14

Spring bean的生命周期

　　　　　　　　　　ApplicationContext Bean生命周期流程

Spring（三）--Spring bean的生命周期

1.需要的实体类

ackage com.xdf.bean;

import org.springframework.beans.BeansException;

import org.springframework.beans.factory.*;

/**

 * 学生的实体类

 *

 * Aware本意就是察觉，感觉

 * 01.实现了BeanNameAware，就是让student类感觉到自己在容器中的id或者是name

 * 02.实现了BeanFactoryAware，就是让student类感觉到自己在容器中所属的bean工厂

 * 03.实现了InitializingBean，就是为了执行初始化之后的操作 ,但是对spring产生了依赖

 *         后续使用反射机制 init-method 来消除对spring的依赖

 * 04.实现了DisposableBean，就是为了执行bean销毁之后的操作 ,但是对spring产生了依赖

 *         后续使用反射机制 destroy-method 来消除对spring的依赖

 */

public class Student implements BeanNameAware,BeanFactoryAware,InitializingBean,DisposableBean{

    private  int  age;  //年龄

    private  String  stuName; //姓名

    private  String  beanName; //bean在容器中的id或者name

    private BeanFactory beanFactory; //bean所在的工厂

    public Student() {

        System.out.println("===Student类中的无参构造===");

    }

    //BeanNameAware接口中的setBeanName（）

    public void setBeanName(String beanName) {

        System.out.println("===执行了BeanNameAware接口中的setBeanName（）===");

        this.beanName=beanName;

    }

    //BeanFactoryAware中的setBeanFactory（）

    public void setBeanFactory(BeanFactory beanFactory) throws BeansException {

        System.out.println("===执行了BeanFactoryAware中的setBeanFactory（）===");

        this.beanFactory=beanFactory;

    }

    public void initMethod(){

        System.out.println("===Student类中的initMethod（）===");

    }

    public void afterPropertiesSet() throws Exception {

        System.out.println("===InitializingBean中的afterPropertiesSet()===");

    }

    public  void myDestroy(){

        System.out.println("===Student类中的myDestroy（）===");

    }

    public void destroy() throws Exception {

        System.out.println("===DisposableBean中的destroy()===");

    }

    public int getAge() {

        return age;

    }

    public void setAge(int age) {

        System.out.println("===Student类中给属性赋值 setAge()===");

        this.age = age;

    }

    public String getStuName() {

        return stuName;

    }

    public void setStuName(String stuName) {

        System.out.println("===Student类中给属性赋值 setStuName()===");

        this.stuName = stuName;

    }

    public String getBeanName() {

        return beanName;

    }

    public BeanFactory getBeanFactory() {

        return beanFactory;

    }

    @Override

    public String toString() {

        return "Student{" +

                "age=" + age +

                ", stuName='" + stuName + '\'' +

                '}';

    }

2.需要的InstantiationAwareBeanPostProcessorAdapter

package com.xdf.bean;

import org.springframework.beans.BeansException;

import org.springframework.beans.PropertyValues;

import org.springframework.beans.factory.config.InstantiationAwareBeanPostProcessorAdapter;

import java.beans.PropertyDescriptor;

/**

 * bean实例化之前 和之后

 */

public class MyInitAwareBeanpostAdpater  extends InstantiationAwareBeanPostProcessorAdapter{

    public  MyInitAwareBeanpostAdpater(){

        System.out.println("*****MyInitAwareBeanpostAdpater的无参构造*****");

    }

    //在实例化bean之前调用

    @Override

    public Object postProcessBeforeInstantiation(Class<?> beanClass, String beanName) throws BeansException {

        System.out.println("*****执行了MyInitAwareBeanpostAdpater的 postProcessBeforeInstantiation *****");

        return null; //底层返回的就是null

    }

    //在实例化bean之后调用

    @Override

    public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {

        System.out.println("*****执行了MyInitAwareBeanpostAdpater的 postProcessAfterInitialization *****");

        return bean;

    }

    @Override

    public PropertyValues postProcessPropertyValues(PropertyValues pvs, PropertyDescriptor[] pds, Object bean, String beanName) throws BeansException {

        System.out.println("*****执行了MyInitAwareBeanpostAdpater的 postProcessPropertyValues *****");

        return pvs;

    }

}

3.需要的BeanPostProcessor

package com.xdf.bean;

import org.springframework.beans.BeansException;

import org.springframework.beans.factory.config.BeanPostProcessor;

/**

 * Processor  本意是加工 处理的意思！

 *

 * 实现了BeanPostProcessor

 */

public class MyBeanPostProcessor implements BeanPostProcessor {

    public MyBeanPostProcessor(){

        System.out.println("===MyBeanPostProcessor的无参构造方法 ===");

    }

    public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {

        System.out.println("===执行了BeanPostProcessor中的 postProcess ==Before==Initialization  ===");

        return bean;

    }

    public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {

        System.out.println("===执行了BeanPostProcessor中的 postProcess ==After==Initialization  ===");

        return bean;

    }

}

4.需要的BeanFactoryPostProcessor

package com.xdf.bean;

import org.springframework.beans.BeansException;

import org.springframework.beans.factory.config.BeanDefinition;

import org.springframework.beans.factory.config.BeanFactoryPostProcessor;

import org.springframework.beans.factory.config.BeanPostProcessor;

import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;

/**

 * Processor  本意是加工 处理的意思！

 *

 * 实现了BeanFactoryPostProcessor   工厂的后处理器

 */

public class MyBeanFactoryPostProcessor implements BeanFactoryPostProcessor {

    public MyBeanFactoryPostProcessor(){

        System.out.println("===MyBeanFactoryPostProcessor的无参构造方法 ===");

    }

    public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {

        System.out.println("===MyBeanFactoryPostProcessor的postProcessBeanFactory ===");

        BeanDefinition beanDefinition = beanFactory.getBeanDefinition("student");

        beanDefinition.getPropertyValues().addPropertyValue("stuName","小白");

    }

}

5.需要的xml文件配置

<?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"

       xmlns:aop="http://www.springframework.org/schema/aop"

       xmlns:tx="http://www.springframework.org/schema/tx"

       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

        http://www.springframework.org/schema/tx

        http://www.springframework.org/schema/tx/spring-tx.xsd

        http://www.springframework.org/schema/aop

        http://www.springframework.org/schema/aop/spring-aop.xsd">

    <!--配置MyBeanPostprocessor   容器级别的 当前xml文件中所有的bean都会执行MyBeanPostProcessor中的方法-->

    <bean class="com.xdf.bean.MyBeanPostProcessor"/>

    <!--配置MyBeanFactoryPostprocessor 容器级别的  同上-->

    <bean class="com.xdf.bean.MyBeanFactoryPostProcessor"/>

    <!--配置MyInitAwareBeanpostAdpater  容器级别的  同上-->

    <bean class="com.xdf.bean.MyInitAwareBeanpostAdpater"/>

    <!-- 配置Student 的实体对象-->

    <bean id="student" class="com.xdf.bean.Student" init-method="initMethod" destroy-method="myDestroy">

         <property name="age" value="20"/>

         <property name="stuName" value="小黑"/>

    </bean>

</beans>

6.需要的测试代码

/**

 * 测试bean生命周期

 */

public class LifeCycle {

    public static void main(String[] args) {

        ApplicationContext  context=new ClassPathXmlApplicationContext("spring.xml");

        Student student= context.getBean("student", Student.class);

        System.out.println(student);

        ((ClassPathXmlApplicationContext)context).close();  //关闭容器

    }

}

　　

　　　　未完待续！！！

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