Spring系列：ApplicationContext和BeanFactory对比区别

目录

​​基础​​

​​对比​​

​​demo​​

​​配置方式​​

​​注解方式​​

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基础

​​Spring系列：IOC依赖注入（根据类型查找）实例​​

对比

Spring Bean 的维护和生命周期管理均在 BeanFactory 实现类中，绝多大数是指 DefaultListableBeanFactory

ApplicationContext是BeanFactory的子接口。

当byType是BeanFactory.class的时候，获得是的ApplicationContext中的DefaultListableBeanFactory对象。(ApplicationContext中每次getBean()都是通过DefaultListableBeanFactory来查找bean对象的)

 

真正的IOC的底层实现就是BeanFactory的实现类，因为ApplicationContext是委托DefaultListableBeanFactory来操作getBean等方法的

demo

配置方式

ApplicationContext applicationContext = new ClassPathXmlApplicationContext("classpath:/META-INF/content-inject.xml") ;



        //自定义bean
        UserRepos userRepos = applicationContext.getBean("userRepos", UserRepos.class) ;

        System.out.println(  userRepos.getObjectFactory().getObject()== applicationContext  );
        System.out.println(userRepos.getBeanFactory() == applicationContext);
        System.out.println(userRepos.getBeanFactory() == applicationContext.getAutowireCapableBeanFactory());

true

false

true

注解方式

package com.test;

import com.test.pojo.User;
import org.springframework.beans.factory.ListableBeanFactory;
import org.springframework.beans.factory.support.DefaultListableBeanFactory;
import org.springframework.beans.factory.xml.XmlBeanDefinitionReader;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.annotation.Bean;

import java.util.Map;

public class IOCDemo {


    public static void main(String[] args) {
        AnnotationConfigApplicationContext applicationContext = new AnnotationConfigApplicationContext();
        applicationContext.register( IOCDemo.class) ;
        applicationContext.refresh() ;
        lookupBeans(applicationContext);
    }

    @Bean
    public User user(){
        User u = new User();
        u.setId(1);
        u.setName("NIO");
        return u ;
    }

    private static void lookupBeans(AnnotationConfigApplicationContext beanFactory) {
        if(beanFactory instanceof ListableBeanFactory){
            Map<String,User> users =  beanFactory.getBeansOfType(User.class);
            System.out.println(users);
        }
    }




}

{user=User{id=1, name='NIO'}}