01.BeanFactory实现

/*
* beanFactory 不会做的事：
*  1.不会主动调用BeanFactory 后处理器
*  2.不会主动添加Bean后处理器
*  3.不会主动初始化单例(懒加载)
*  4.不会解析beanFactory 还不会解析 ${} 与 #{}
* */

@Slf4j
@SpringBootApplication
public class SpringbootSsmApplication {
   public static void main(String[] args){
      ConfigurableApplicationContext context = SpringApplication.run(SpringbootSsmApplication.class, args);
      // DefaultListableBeanFactory 是 BeanFactory 的一个实现类
      DefaultListableBeanFactory beanFactory = new DefaultListableBeanFactory();

      // bean定义
      AbstractBeanDefinition beanDefinition = BeanDefinitionBuilder.genericBeanDefinition(Config.class).setScope("singleton").getBeanDefinition();
      beanFactory.registerBeanDefinition("config", beanDefinition);

      // 给 beanFactory 添加一些常用的后处理器
      AnnotationConfigUtils.registerAnnotationConfigProcessors(beanFactory);

      // 解析bean
      beanFactory.getBeansOfType(BeanFactoryPostProcessor.class).values().stream().forEach(beanFactoryPostProcessor -> {
         beanFactoryPostProcessor.postProcessBeanFactory(beanFactory);
      });

      for (String name : beanFactory.getBeanDefinitionNames()) {
         System.out.println(name);
      }

      // Bean 后处理器，针对bean的生命周期的各个阶段提供扩展，例如@Autowired、@Resource....
      beanFactory.getBeansOfType(BeanPostProcessor.class).values().forEach(beanFactory::addBeanPostProcessor);

      // 准备好初始化所有单例bean对象
      beanFactory.preInstantiateSingletons();
      System.out.println("-------------------");
      System.out.println(beanFactory.getBean(Bean1.class).getBean2());

   }

   @Configuration
   static class Config{
      @Bean
      public Bean1 bean1(){
         return new Bean1();
      }
      @Bean
      public Bean2 bean2(){
         return new Bean2();
      }

   }

   static class Bean1{
      @Autowired
      private Bean2 bean2;
      public Bean1(){
         log.debug("bean1构造");
      }

      public Bean2 getBean2(){
         return bean2;
      }
   }

   static class Bean2{
      public Bean2(){
         log.debug("bean2构造");
      }
   }

}