Spring mvc Spring Boot为自定义FreeMarker登录页面发送空json

在SpringBoot中，我为自定义MVC添加了带有@EnableWebMvc注释的@Configuration。它使用src/main/resources/templates下的Freemarker模板。问题是登录页面被作为空json发送回浏览器。我是否需要添加额外的谈判内容或其他内容？Thx

@Configuration
@EnableWebMvc
public class WebMvcConfig 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);

    FreeMarkerViewResolver viewResolver = new FreeMarkerViewResolver();
    viewResolver.setPrefix("/templates/");
    viewResolver.setSuffix(".ftl");

    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;
}
  ....

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登录控制器缺少客户端HTTP GET的适当内容类型设置，因此我添加了这个products属性。

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@RequestMapping（value=“/login”，products=“application/xml”）

登录控制器缺少客户端HTTP GET的适当内容类型设置，因此我添加了这个products属性。 @请求映射（value=“/login”，products=“application/xml”）

@Controller
@SessionAttributes
public class LoginController {

  @RequestMapping("/login")
   public String login() {
      return "login";
  }
}