BeanFactory与ApplicationContext的区别

BeanFactory是Spring底层IOC容器;

ApplicationContext是具备应用特性的BeanFactory超集;

public class DependencyInjectionDemo {public static void main(String[] args) {// 配置 XML 配置文件// 启动 Spring 应用上下文
//        BeanFactory beanFactory = new ClassPathXmlApplicationContext
//        ("classpath:META-INF/dependency-injection-context.xml");ApplicationContext applicationContext= new ClassPathXmlApplicationContext("classpath:META-INF/dependency-injection-context.xml");// 依赖来源一：自定义 BeanUserRepository userRepository = applicationContext.getBean("userRepository", UserRepository.class);
//        System.out.println(userRepository.getUsers());whoIsIocContainer(userRepository, applicationContext);// 依赖来源二：依赖注入（内建依赖）-> DefaultListableBeanFactorySystem.out.println(userRepository.getBeanFactory());ObjectFactory<ApplicationContext> userObjectFactory = userRepository.getObjectFactory();// ApplicationContextSystem.out.println(userObjectFactory.getObject());// trueSystem.out.println("内建 Bean 对象：" + (userObjectFactory.getObject() == applicationContext));// 依赖查找 (错误)
//        System.out.println(applicationContext
//        .getBean(BeanFactory.class));// 依赖来源三：容器内建 BeanEnvironment environment = applicationContext.getBean(Environment.class);System.out.println("获取 Environment 类型的 Bean：" + environment);}private static void whoIsIocContainer(UserRepository userRepository,ApplicationContext applicationContext) {// ConfigurableApplicationContext <- ApplicationContext <- BeanFactory// ConfigurableApplicationContext#getBeanFactory()// 这个表达式为什么会不成立// 因为 AbstractRefreshableApplicationContext创建了DefaultListableBeanFactory，他们俩个并不是一个对象// falseSystem.out.println("内建非 Bean 对象（依赖）: " + (userRepository.getBeanFactory() == applicationContext));// ApplicationContext is BeanFactory}}

执行结果:

内建非 Bean 对象（依赖）: false
org.springframework.beans.factory.support.DefaultListableBeanFactory@124c278f: defining beans [user,superUser,objectFactory,userRepository]; root of factory hierarchy
org.springframework.context.support.ClassPathXmlApplicationContext@6fb554cc, started on Thu Oct 08 17:01:25 CST 2020
内建 Bean 对象：true
获取 Environment 类型的 Bean：StandardEnvironment {activeProfiles=[], defaultProfiles=[default], propertySources=[PropertiesPropertySource {name='systemProperties'}, SystemEnvironmentPropertySource {name='systemEnvironment'}]}