@ComponentScan注释适用于非@Configuration类

Question

Spring参考文档说明如下：

/**
 * Java-based configuration class which defines root package to start scanning from.
 */
@ComponentScan
public class ComponentScanPackageMarker {
}

/**
 * Class annotated with <b>stereotype</b> annotation is a candidate for automatic detection and registering as
 * {@link BeanDefinition} instance.
 */
@Component
public class Pen {

    private Ink ink;

    @Autowired
    public Pen(Ink ink) {
        this.ink = ink;
    }
}

/**
 * Auto-detected class which will be used as auto-wiring candidate for another auto-detected component.
 */
@Component
public class Ink {
}

ComponentScanPackageMarker类故意省略了@Configuration注释。我已经测试了组件扫描和自动连接功能。令我吃惊的是,一切都很顺利：

@Test
public void shouldAutoDetectAndRegisterBeans() {
    try (AnnotationConfigApplicationContext context =
                 new AnnotationConfigApplicationContext(ComponentScanPackageMarker.class)) {
        Pen pen = context.getBean(Pen.class);
        Assert.assertNotNull(pen);
        Ink ink = context.getBean(Ink.class);
        Assert.assertNotNull(ink);
    }
}

组件扫描的这种行为是故意的吗？为什么即使没有@Configuration注释也能工作？

Answer 1

是的。我认为@ComponentScan的工作是扫描给定的包，并注册用原型注释(@Component、@Configuration、@Service和@Repository)注释的bean，如果找到的话，而@Configuration的工作是将方法的（用@bean注释的）返回值注册为容器中的bean。

如果我错了就纠正我。