java - 如何将逻辑与 Controller 分离并使用注释将其放入某些处理程序？

Question

在我们的项目中，我们已经有了一些必要的 Controller ，我的任务是让它变得更容易。它应该像这样工作:我只需在 Controller 下放置一个注释，然后处理程序完成其所有工作。我已经拥有的:

/**
 * This annotation marks collector methods
 */
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
public @interface Collect {

}

@Target({ElementType.METHOD, ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
public @interface Collectors {

    /**
     * An array of subclasses that can load and provide values for
     * generating a ModelMap.
     */
    Class<?>[] value();
}

我找不到任何示例。 Controller 示例:

@Controller
public class TestController {
    private final SchoolService schoolService;

    private final TeacherService teacherService;


    public TestController(SchoolService schoolService, TeacherService teacherService) {
        this.schoolService = schoolService;
        this.teacherService = teacherService;
    }

    /**
     * Saves the static list of users in model and renders it
     * via freemarker template.
     *
     * @param model
     * @return The index view (FTL)
     */
    @Collectors(SchoolCollector.class)
    @RequestMapping(value = "freemarker/freemarkertest", method = RequestMethod.GET)
    public String index(@ModelAttribute("model") ModelMap model) {
        List<SchoolDTO> schoolList = new ArrayList<SchoolDTO>();
        schoolList = schoolService.findAll();
        model.addAttribute("schoolList", schoolList);
        return "freemarkertest";
    }

    /**
     * Add a new School
     *
     * @param schoolDTO
     * @return Redirect back to same /freemarkertest page to display school list, if successful
     */
    @Collectors(SchoolCollector.class)
    @RequestMapping(value = "freemarker/freemarkertest/add", method = RequestMethod.POST)
    public String add(@ModelAttribute("schoolDTO") SchoolDTO schoolDTO) {
        if(schoolDTO.getName() != null && !schoolDTO.getName().isEmpty() &&
                schoolDTO.getEnabled() != null) {
            schoolService.save(schoolDTO);
            return "redirect:";
        } else {
            return "redirect:error"; //TODO: create error page
        }

    }

    /**
     * Get list of teachers.
     *
     * @param model
     * @param schoolId
     * @return The index view (FTL)
     */
    @Collectors(SchoolCollector.class)
    @RequestMapping(value = "freemarker/teachers/{schoolId}", method = RequestMethod.GET)
    public String index(@ModelAttribute("model") ModelMap model, @PathVariable Long schoolId) {
        List<TeacherDTO> teachers = teacherService.getAllBySchoolId(schoolId);
        model.addAttribute("teachersList", teachers);
        model.addAttribute("schoolId", schoolId);
        return "teachers";
    }

}

Answer 1

您需要的是 HandlerInterceptorAdapters。这些必须在您的 SpringMvc-servlet.xml 中定义，否则它们将拦截您的所有请求。

public class CollectorHandler extends HandlerInterceptorAdapter {

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        if (handler instanceof HandlerMethod && modelAndView != null) {
            HandlerMethod handlerMethod = (HandlerMethod) handler;
            if (handlerMethod.getMethodAnnotation(Collectors.class) == null) {
                return;
            }

            /**
              * Your logic here
              */
        }
    }
}

进一步阅读:

• http://www.baeldung.com/spring-mvc-handlerinterceptor
• https://www.mkyong.com/spring-mvc/spring-mvc-handler-interceptors-example/

PS:我还想补充一点，您的代码将无法工作，因为其中有一些“错误”...返回字符串而不是对象作为示例