组件扫描会妨碍 bean 初始化吗？

Question

我在尝试复制一个简单的 spring OAuth 项目 sparklr2 时遇到了这个问题。源代码在这里 https://github.com/spring-projects/spring-security-oauth/tree/master/samples/oauth2/sparklr

源代码运行非常完美，当我使用 tomcat 调试它时，它会初始化 WebMvcConfigurerAdapter 中的所有 @Bean，包括控制器。但注意到 @ComponentScan() 没有被使用。

然后我创建了自己的 MVC 项目，复制了几乎 100% 的代码，但我使用的是 WebApplicationInitializer 而不是 AbstractDispatcherServletInitializer。我使用 WebApllicationInitializer 因为我只学会了这种编码 MVC 的方式。

然后我运行项目，@Bean初始化。然后我用我的浏览器检查 /login，得到 404。这可能是由于 spring 不知道我有控制器，然后我将 @ComponentScan 添加到我的配置 class，/login 现在出现了。但奇怪的是，所有与Controller相关的@Bean，都没有被初始化。因此，当我调用这些控制器的任何方法时，由于它们的属性未初始化，因此没有对象或空异常。

所以，我的意思是，该示例如何工作，我的意思是控制器和 jsp 在不使用 @ComponentScan 的情况下正确处理和响应？从不同的角度来看，为什么@ComponentScan 会阻止@Bean 在我的项目中被初始化？

我的 WebApplicationInitializer

@Configuration
@EnableWebMvc
@ComponentScan("umedia.test.oauth.controller")
public class MvcConfig extends WebMvcConfigurerAdapter {

    @Bean
    public static PropertySourcesPlaceholderConfigurer propertySourcesPlaceholderConfigurer() {
        return new PropertySourcesPlaceholderConfigurer();
    }

    @Bean
    public ContentNegotiatingViewResolver contentViewResolver()
            throws Exception {
        ContentNegotiationManagerFactoryBean contentNegotiationManager = new ContentNegotiationManagerFactoryBean();
        contentNegotiationManager.addMediaType("json",
                MediaType.APPLICATION_JSON);

        InternalResourceViewResolver viewResolver = new InternalResourceViewResolver();
        viewResolver.setViewClass(JstlView.class);
        viewResolver.setPrefix("/WEB-INF/views/");
        viewResolver.setSuffix(".jsp");

        MappingJackson2JsonView defaultView = new MappingJackson2JsonView();
        defaultView.setExtractValueFromSingleKeyModel(true);

        ContentNegotiatingViewResolver contentViewResolver = new ContentNegotiatingViewResolver();
        contentViewResolver
                .setContentNegotiationManager(contentNegotiationManager
                        .getObject());
        contentViewResolver.setViewResolvers(Arrays
                .<ViewResolver> asList(viewResolver));
        contentViewResolver.setDefaultViews(Arrays.<View> asList(defaultView));
        return contentViewResolver;
    }



    @Bean
    public PhotoServiceImpl photoServices() {
        List<PhotoInfo> photos = new ArrayList<PhotoInfo>();
        photos.add(createPhoto("1", "marissa"));
        photos.add(createPhoto("2", "paul"));
        photos.add(createPhoto("3", "marissa"));
        photos.add(createPhoto("4", "paul"));
        photos.add(createPhoto("5", "marissa"));
        photos.add(createPhoto("6", "paul"));

        PhotoServiceImpl photoServices = new PhotoServiceImpl();
        photoServices.setPhotos(photos);
        return photoServices;
    }

    // N.B. the @Qualifier here should not be necessary (gh-298) but lots of
    // users report needing it.
    @Bean
    public AdminController adminController(
            TokenStore tokenStore,
            @Qualifier("consumerTokenServices") ConsumerTokenServices tokenServices,
            SparklrUserApprovalHandler userApprovalHandler) {
        AdminController adminController = new AdminController();
        adminController.setTokenStore(tokenStore);
        adminController.setTokenServices(tokenServices);
        adminController.setUserApprovalHandler(userApprovalHandler);
        return adminController;
    }

    // this url, do I need to change it?
    private PhotoInfo createPhoto(String id, String userId) {
        PhotoInfo photo = new PhotoInfo();
        photo.setId(id);
        photo.setName("photo" + id + ".jpg");
        photo.setUserId(userId);
        photo.setResourceURL("/org/springframework/security/oauth/examples/sparklr/impl/resources/"
                + photo.getName());
        return photo;
    }

    @Override
    public void configureDefaultServletHandling(
            DefaultServletHandlerConfigurer configurer) {
        configurer.enable();
    }

    @Bean
    public PhotoServiceUserController photoServiceUserController(
            PhotoService photoService) {
        PhotoServiceUserController photoServiceUserController = new PhotoServiceUserController();
        return photoServiceUserController;
    }

    @Bean
    public PhotoController photoController(PhotoService photoService) {
        PhotoController photoController = new PhotoController();
        photoController.setPhotoService(photoService);
        return photoController;
    }

    @Bean
    public AccessConfirmationController accessConfirmationController(
            ClientDetailsService clientDetailsService,
            ApprovalStore approvalStore) {
        AccessConfirmationController accessConfirmationController = new AccessConfirmationController();
        accessConfirmationController
                .setClientDetailsService(clientDetailsService);
        accessConfirmationController.setApprovalStore(approvalStore);
        return accessConfirmationController;
    }

/*  @Bean
    public ViewResolver viewResolver() {
        InternalResourceViewResolver viewResolver = new InternalResourceViewResolver();
        viewResolver.setViewClass(JstlView.class);
        viewResolver.setPrefix("/WEB-INF/views/");
        viewResolver.setSuffix(".jsp");

        return viewResolver;
    }*/

    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        registry.addResourceHandler("/resources/**").addResourceLocations(
                "/resources/");
    }

}

Answer 1

那么，您有 @ComponentScan 与控制器上的 @Controller 交互 + 仍然创建 @Bean 吗？

作为第一步，尝试删除 @Beans 并尝试使用 @Autowired 在控制器的构造函数中注入依赖项。然后@ComponentScan 应该识别 @Controller，注入依赖项并使用 @RequestMapping 没有问题。

组件扫描会妨碍 bean 初始化吗？

component-scan get in the way of bean initialization?

spring

spring-mvc

component-scan