使用Spring IoC容器：选BeanFactory还是ApplicationContext？

<?xml version="1.0" encoding="UTF-8"?>
<beans
        xmlns="http://www.springframework.org/schema/beans"
        xmlns:context="http://www.springframework.org/schema/context"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:schemaLocation="http://www.springframework.org/schema/beans
        https://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context
        https://www.springframework.org/schema/context/spring-context.xsd">

<!--    <context:annotation-config/>-->

<!--    <context:component-scan base-package="org.acme" />-->

    <!-- Root BeanDefinition 不需要合并，不存在 parent -->
    <!-- 普通 beanDefinition GenericBeanDefinition -->
    <!-- 经过合并后 GenericBeanDefinition 变成 RootBeanDefinition -->
    <bean id="user" class="org.ibyte.thinking.in.spring.ioc.domain.User">
        <property name="id" value="1"/>
        <property name="name" value="小码哥"/>
    </bean>

    <!-- 普通 beanDefinition GenericBeanDefinition -->
    <!-- 合并后 GenericBeanDefinition 变成 RootBeanDefinition，并且覆盖 parent 相关配置-->
    <!-- primary = true , 增加了一个 address 属性 -->
    <bean id="superUser" class="org.ibyte.thinking.in.spring.ioc.domain.SuperUser" parent="user"
          primary="true">
        <property name="address" value="深圳"/>
    </bean>

    <bean id="objectFactory" class="org.springframework.beans.factory.config.ObjectFactoryCreatingFactoryBean">
        <property name="targetBeanName" value="user"/>
    </bean>

</beans>

/**
 * {@link BeanFactory} 作为 IoC 容器示例
 *
 * @author lisz (shangzhi.ibyte@gmail.com)
 */
public class BeanFactoryAsIoCContainerDemo {

    public static void main(String[] args) {
        // 创建 BeanFactory 容器
        DefaultListableBeanFactory beanFactory = new DefaultListableBeanFactory();
        XmlBeanDefinitionReader reader = new XmlBeanDefinitionReader(beanFactory);
        // XML 配置文件 ClassPath 路径
        String location = "classpath:/META-INF/dependency-lookup-context.xml";
        // 加载配置
        int beanDefinitionsCount = reader.loadBeanDefinitions(location);
        System.out.println("Bean 定义加载的数量：" + beanDefinitionsCount);
        // 依赖查找集合对象
        lookupCollectionByType(beanFactory);
    }

    private static void lookupCollectionByType(BeanFactory beanFactory) {
        if (beanFactory instanceof ListableBeanFactory) {
            ListableBeanFactory listableBeanFactory = (ListableBeanFactory) beanFactory;
            Map<String, User> users = listableBeanFactory.getBeansOfType(User.class);
            System.out.println("查找到的所有的 User 集合对象：" + users);
        }
    }
}

/**
 * 注解能力 {@link ApplicationContext} 作为 IoC 容器示例
 *
 * @author lisz (shangzhi.ibyte@gmail.com)
 */
@Configuration
public class AnnotationApplicationContextAsIoCContainerDemo {

    public static void main(String[] args) {
        // 创建Bean容器
        AnnotationConfigApplicationContext applicationContext = new AnnotationConfigApplicationContext();
        // 将当前类 AnnotationApplicationContextAsIoCContainerDemo 作为配置类（Configuration Class）
        applicationContext.register(AnnotationApplicationContextAsIoCContainerDemo.class);
        // 启动应用上下文
        applicationContext.refresh();

        // 依赖查找集合对象
        lookupCollectionByType(applicationContext);

        // 关闭应用上下文
        applicationContext.close();
    }

    /**
     * 通过 Java 注解的方式，定义了一个 Bean
     */
    @Bean
    public User user() {
        User user = new User();
        user.setId(1L);
        user.setName("小码哥");
        return user;
    }

    private static void lookupCollectionByType(BeanFactory beanFactory) {
        if (beanFactory instanceof ListableBeanFactory) {
            ListableBeanFactory listableBeanFactory = (ListableBeanFactory) beanFactory;
            Map<String, User> users = listableBeanFactory.getBeansOfType(User.class);
            System.out.println("查找到的所有的 User 集合对象：" + users);
        }
    }
}