public class BeanServiceImpl implements BeanService {
}

@Configuration
public class ConfigurationBean {

    @Bean
    public BeanService beanService() {
        BeanServiceImpl beanService = new BeanServiceImpl();
        System.out.println("beanService: " + beanService);
        return beanService;
    }

    @Bean
    //@Bean 如果不知道name，默認(rèn)bean的name為方法名，下面等同于@Bean("beanService1")
    public BeanService beanService1() {
        BeanServiceImpl beanService1 = new BeanServiceImpl();
        System.out.println("beanService1: " + beanService1);
        return beanService1;
    }
}

@Component
public class SetterBean {

    private BeanService bs;

    public SetterBean(BeanService beanService) {
        bs = beanService;
        System.out.println("有參構(gòu)造：" + bs);
    }
}

protected BeanWrapper createBeanInstance(String beanName, RootBeanDefinition mbd, @Nullable Object[] args) {
		... ... 
		// No special handling: simply use no-arg constructor.
		return instantiateBean(beanName, mbd);
	}

protected BeanWrapper createBeanInstance(String beanName, RootBeanDefinition mbd, @Nullable Object[] args) {
		... ...
		// Candidate constructors for autowiring?
		Constructor<?>[] ctors = determineConstructorsFromBeanPostProcessors(beanClass, beanName);
		if (ctors != null || mbd.getResolvedAutowireMode() == AUTOWIRE_CONSTRUCTOR ||
				mbd.hasConstructorArgumentValues() || !ObjectUtils.isEmpty(args)) {
			return autowireConstructor(beanName, mbd, ctors, args);
		}
		... ...
	}

@Component
public class SetterBean {

    private BeanService bs;

    public SetterBean(BeanService beanService) {
        bs = beanService;
        System.out.println("有參構(gòu)造：" + bs);
    }

	//@Autowired
    public SetterBean(BeanService beanService, BeanService beanService1) {
        bs = beanService;
        System.out.println("有參構(gòu)造：" + bs + "--------" + beanService1);
    }
}