如何将逻辑从控制器中分离出来，并使用注释将其放在某些处理程序中

Question

在我们的项目中，我们已经有一些必要的控制器，我的任务是使其更容易。它应该这样工作：我只是将注释放在控制器下，而处理程序可以完成所有工作。我已经拥有的东西：

/**
 * 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();
}

我找不到任何示例如何做。控制器示例：

@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HandlerInterceptoradapter。这些必须在您的SpringMvc-servlet.xml中定义，而这些都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
              */
        }
    }
}

用于进一步阅读：

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

ps：我还想补充说，您的代码无法正常工作，因为其中有一些"错误" ...返回字符串而不是对象作为示例