Spring Thymeleaf - 用于显示 HTML 项目的调用服务方法 bool 值

Question

在我的 header HTML 中，我显示了一个 UL/LI 菜单，其中一个 LI 项目的可见性取决于服务方法调用。

我试过这个:

家庭 Controller

@Controller
public class HomeController {
    private static final Logger log = LogManager.getLogger(HomeController.class);

    @Autowired 
    private EtdService etdService;

    @GetMapping("/home")
    public String home(Model model) throws EtdException {

        model.addAttribute("tierTemplate", etdService.getTierTemplate());  
        // Also tried this explicitly
        model.addAttribute("etdService", etdService);
        return "home";
    }
}

服务接口(interface)(EtdService)

public interface EtdService {
  boolean isChangeUserAllowed();
}

服务实现 (EtdServiceImpl)

@Component
public class EtdServiceImpl implements EtdService {

    @Override
    public boolean isChangeUserAllowed() {
        System.out.println("Got here");
        return false;
    }

}

HTML:

<li th:if="${@etdService.isChangeUserAllowed()}" class="nav-item dropdown" id="changeUserPanel" role="presentation">
<!-- ... Definition of this LI -- note can't put a new DIV in a UL list ... -->
</li>

错误:

Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No bean named 'etdService' available
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBeanDefinition(DefaultListableBeanFactory.java:772) ~[spring-beans-5.1.4.RELEASE.jar:5.1.4.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getMergedLocalBeanDefinition(AbstractBeanFactory.java:1221) ~[spring-beans-5.1.4.RELEASE.jar:5.1.4.RELEASE]

Answer 1

除了bphilipnyc的回答(将直接值设置到模型中)，

model.addAttribute("isChangeUserAllowed", etdService.isChangeUserAllowed());

如果您需要全局化通用模型属性而不是每次都重新添加，一个解决方案是一个带有@ModelAttribute 的@ControllerAdvice 类，例如

/**
 * This class is used to globalize common Model Attributes without re-adding every time
 * The approach is to mark it as @ControllerAdvice to make it apply to every Controller method, 
 * and implement a @ModelAttribute Model-Adder to append to the model on every Controller method.
 */

// Makes the methods of this class apply to all Controller Request methods
@ControllerAdvice
public class GlobalController {

    @Autowired
    MyService myService;

    @ModelAttribute   // A Model Attribute Adder method
    public void setGlobalModelAttributes(HttpServletRequest request, Model model) {

        model.addAttribute("isChangeUserAllowed", myService.isChangeUserAllowed());
        model.addAttribute("currentUserFullName", myService.getCurrentUserFullName());

    }       
}

更多例子

https://stackoverflow.com/a/33879102/1005607

https://www.baeldung.com/spring-mvc-and-the-modelattribute-annotation