SPRING02_核心注解、Bean、primary、DependsOn、Lazy、Scope、ComponentScan、详解Import、Lookup注解（五）

@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface Import {
  /**
   * 1.直接写class person = Person{name='null'}:利用无参构造创建出对象放在容器中
   * 2.ImportSelector
   * 3.ImportBeanDefinitionRegistrar
   * {@link Configuration @Configuration}, {@link ImportSelector},
   * {@link ImportBeanDefinitionRegistrar}, or regular component classes to import.
   */
  Class<?>[] value();
}

@Configuration
   @Import(Person.class)
public class MyConfig {
}

package com.xiaozhi.bean;
public class Cat {
  private String name;
  public void setName(String name) {
    this.name = name;
  }
  public String getName() {
    return name;
  }
}

@Configuration
// @Import(Person.class)
//如果要导入两个用下面的方式
@Import({Person.class, MyConfig.MyImportBeanDefinitionRegistrar.class})
public class MyConfig {
//  @Bean
//  public Person person(){
//    Person person=new Person();
//    person.setName("TANGZHI");
//    return person;
//  }
  /**
   * BeanDefinitionRegistry:Bean定义信息注册中心,图纸中心
   *    它里面都是BeanDefinition
   */
  static class MyImportBeanDefinitionRegistrar implements ImportBeanDefinitionRegistrar {
    @Override
    public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata,
                      BeanDefinitionRegistry registry) {
      //BeanDefinition
      RootBeanDefinition catDefinition = new RootBeanDefinition();
      catDefinition.setBeanClass(Cat.class);
      //Spring 这个实例的类型
      registry.registerBeanDefinition("tomcat",catDefinition);
    }
  }
}

public class AnnotationMainTest {
  public static void main(String[] args) {
    ApplicationContext applicationContext = new AnnotationConfigApplicationContext(MyConfig.class);
//    Person person = applicationContext.getBean(Person.class);
//    System.out.println("person = " + person);
    String[] names = applicationContext.getBeanDefinitionNames();
    /**
     * 如果使用的是import方式导入的,那么这个bean的名字就是全类名
     * com.xiaozhi.bean.Person
     * tomcat
     */
    for (String name : names) {
      System.out.println(name);
    }
  }
}