spring- BeanFactory与ApplicationContext

1. 概述

我们常常将BeanFactory称为容器，将ApplicationContext称为上下文，一直以来，人们认为者两者是同一个事物，我们来探究一下他们之间的关系。接下来来看一个例子

2. 例子说明

配置类

package org.liyuqiu.spring.ioc.test;

import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;

@Configuration
@ComponentScan("org.liyuqiu.spring.ioc.test")
public class ContainerConfig {

}

获取信息

package org.liyuqiu.spring.ioc.test;

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.BeanFactoryAware;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.stereotype.Component;

@Component
public class SpringIoc implements BeanFactoryAware, ApplicationContextAware {
    @Override
    public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
        System.out.println(System.identityHashCode(beanFactory));
        System.out.println(beanFactory.getClass().getName());
    }

    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        System.out.println(System.identityHashCode(applicationContext));
        System.out.println(applicationContext.getClass().getName());
    }
}

启动类

package org.liyuqiu.spring.ioc.test;

import org.springframework.context.annotation.AnnotationConfigApplicationContext;

public class MainContainer {

    public static void main(String[] args) {
        AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(ContainerConfig.class);
        context.close();
    }

}

结果

我们可以看到两者不仅不是一个对象，连类型都不一样。我们来看一下Spring官方如何论述二者的关系：

简而言之，BeanFactory 提供了配置框架和基本功能，ApplicationContext增加了更多针对企业的功能，ApplicationContext是BeanFactory的一个完整的超集。

按照官方的解释：二者是一个包含与被包含的关系，那么在ApplicationContext中我们可以获得根容器吗？

当然我们可以调用getAutowireCapableBeanFactory即可。

@Component
public class SpringIoc implements BeanFactoryAware, ApplicationContextAware {
    private BeanFactory beanFactory;

    @Override
    public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
        this.beanFactory = beanFactory;
        System.out.println(System.identityHashCode(beanFactory));
        System.out.println(beanFactory.getClass().getName());
    }

    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {

        AutowireCapableBeanFactory factory = applicationContext.getAutowireCapableBeanFactory();
        System.out.println(System.identityHashCode(factory.hashCode()));
        System.out.println(factory.getClass().getName());
        System.out.println("两者相等吗:" + (factory == beanFactory));

    }
}
@Component
public class SpringIoc implements BeanFactoryAware, ApplicationContextAware {
    private BeanFactory beanFactory;

    @Override
    public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
        this.beanFactory = beanFactory;
        System.out.println(System.identityHashCode(beanFactory));
        System.out.println(beanFactory.getClass().getName());
    }

    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {

        AutowireCapableBeanFactory factory = applicationContext.getAutowireCapableBeanFactory();
        System.out.println(System.identityHashCode(factory.hashCode()));
        System.out.println(factory.getClass().getName());
        System.out.println("两者相等吗:" + (factory == beanFactory));

    }
}

@Component
public class SpringIoc implements BeanFactoryAware, ApplicationContextAware {
    private BeanFactory beanFactory;

    @Override
    public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
        this.beanFactory = beanFactory;
        System.out.println(System.identityHashCode(beanFactory));
        System.out.println(beanFactory.getClass().getName());
    }

    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {

        AutowireCapableBeanFactory factory = applicationContext.getAutowireCapableBeanFactory();
        System.out.println(System.identityHashCode(factory.hashCode()));
        System.out.println(factory.getClass().getName());
        System.out.println("两者相等吗:" + (factory == beanFactory));

    }
}

结果

3. 两者差异

BeanFactory 接口提供了一种高级配置机制，能够管理任何类型的对象，ApplicationContext是其子接口，增加了以下特性:

• 与Spring的AOP功能轻松集成
• 消息资源处理
• 活动发布
• 应用层特定的上下文

参考:https://juejin.cn/post/6844904061574053901