@Import({User.class, DBHelper.class})
@Configuration(proxyBeanMethods = false)
public class MyConfig {
    @Bean("user1")
    public User user01(){
        User pingguo = new User("pingguo",20);
        pingguo.setPet(tomcatPet());
        return pingguo;
    }
    @Bean("pet1")
    public Pet tomcatPet(){
        return new Pet("tomcat");
    }
}

// 標記這是一個 springboot應用，這個類是主程序類，所有啟動的入口
@SpringBootApplication(scanBasePackages = "com.pingguo")
public class MainApplication {
    public static void main(String[] args) {
        // 返回IOC容器
        final ConfigurableApplicationContext run = SpringApplication.run(MainApplication.class, args);
        // 查看容器里的組件
        final String[] beanDefinitionNames = run.getBeanDefinitionNames();
        for (String name: beanDefinitionNames) {
            System.out.println(name);
        }
        // 從容器中獲取組件
        MyConfig bean = run.getBean(MyConfig.class);
        System.out.println("配置類也是組件：" + bean);
        User user1 = bean.user01();
        User user2 = bean.user01();
        System.out.println(user1 == user2);
        // 依賴關系
        User user01 = run.getBean("user1", User.class);
        Pet pet1 = run.getBean("pet1", Pet.class);
        System.out.println("依賴：" + (user01.getPet() == pet1));
        // @Import 組件
        String[] beanNamesForType = run.getBeanNamesForType(User.class);
        System.out.println("====獲取 User 類型的 bean ====");
        for (String s : beanNamesForType) {
            System.out.println(s);
        }
        System.out.println("====獲取 DBHelper 類型的 bean ====");
        DBHelper bean1 = run.getBean(DBHelper.class);
        System.out.println(bean1);
    }
}