Spring上下文中原型bean中的单例bean

Question

通常在Spring上下文中，如果原型bean被注入到单例bean中，父类的属性将重写原型bean作用域。但是，如果在原型bean作用域中注入一个单例作用域bean会发生什么。仍然使用内部bean的get bean会返回内部bean的新实例吗？

Answer 1

否，prototypebean的所有实例将共享singletonbean的同一实例。
示例:

@Service
public class SingletonBean {
    private int id;
    private static int static_id = 0;

    public SingletonBean() {
        id = static_id++;
    }

    @Override
    public String toString() {
        return "SingletonBean [id=" + id + "]";
    }

}

@Service
@Scope("prototype")
public class PrototypeBean {

    @Autowired
    private SingletonBean singletonBean;
    private int id;

    private static int static_id = 0;

    public PrototypeBean() {
        id = static_id++;
    }

    @Override
    public String toString() {
        return "id=" + id + ", PrototypeBean [singletonBean=" + singletonBean + "]";
    }
}

@SpringBootApplication
public class DemoApplication {

    public static void main(String[] args) {
        ConfigurableApplicationContext context = SpringApplication.run(DemoApplication.class, args);
        PrototypeBean beanA = context.getBean(PrototypeBean.class);
        PrototypeBean beanB = context.getBean(PrototypeBean.class);

        System.out.println(beanA); //id=0, PrototypeBean [singletonBean=SingletonBean [id=0]]
        System.out.println(beanB); //id=1, PrototypeBean [singletonBean=SingletonBean [id=0]]
    }
}

</code>