SpringMVC：带有动态bean对象的输入表单

我有一个等级：Employee->（经理、服务员、厨师）。 我正在尝试使用SpringMVC控制器构建一个web表单，以便能够在DB中创建并保存继承Employee的所有类型。 因此，在推送表单时，我必须将一些模型绑定到视图（JSP-page）。问题是，我的用户将通过{waterer，Cook，Manager}下拉列表来决定创建哪种类型。基于这些信息，我想创建实例并将它们保存在DB中。 我该怎么做？ 标准方法意味着我绑定了这样一个表单：

    @RequestMapping("/new_employee")
    public ModelAndView showEmployeeForm(){
            return new ModelAndView("new_employee","employee",new Employee());
    }

    String pos = webRequest.getParameter("position");
    Employee employee;
    switch (pos) {
            case "1":
                    employee = new Manager();
                    break;
            case "2":
                    employee = new Chef();
                    break;
            case "3":
                    employee = new Waiter();
                    break;
            default:
                    throw new RuntimeException();
    }

但在处理表单的方法中，我将被迫创建给定类型的另一个实例。Smth。像这样：

    @RequestMapping("/new_employee")
    public ModelAndView showEmployeeForm(){
            return new ModelAndView("new_employee","employee",new Employee());
    }

    String pos = webRequest.getParameter("position");
    Employee employee;
    switch (pos) {
            case "1":
                    employee = new Manager();
                    break;
            case "2":
                    employee = new Chef();
                    break;
            case "3":
                    employee = new Waiter();
                    break;
            default:
                    throw new RuntimeException();
    }

有没有更可爱、更受欢迎的方法

问题是，我的用户将决定使用 {服务员、厨师、经理}的下拉列表。根据这一信息，我 要创建实例并将其保存在DB中

我认为您的目标是在不修改现有类的情况下，将设计松散地耦合起来，以添加新类型的员工&创建和保存逻辑，您需要遵循以下步骤：

（1） 创建Employee接口或抽象类类型

（2） 创建经理、服务员、厨师类型（所有实施/扩展员工类型）

（3） 创建

EmployeeService

接口类型并实现

ManagerService

，

WaiterService

等。。通过编写

create

所涉及的特定逻辑（如下所述，如果您对每种类型都有复杂的create逻辑，则可以添加该逻辑以提高灵活性）

（4） 将

showEmployeeForm（）

和

createEmployee（）

添加到您的

Controller

中，并使用

ApplicationContext

动态获取相应的

EmployeeService

对象（它根据用户选择的输入检索对象）。请注意，我们有单独的服务类（bean），我们使用

ApplicationContext

来获得正确的bean（服务员服务、经理服务、厨师服务）来调用相应的

create（）

代码如下所示：

public interface EmployeeService {
   public void create();
}

@Service("WaiterService")
public class WaiterService extends EmployeeService {
   public void create(Waiter waiter) {
     //add Waiter save logic
   }
}

@Service("ChefService")
public void create(Chef chef) {
      //add Chef save logic
   }
}

    @Controller
    public class EmployeeController {

        @Autowired
        private ApplicationContext appContext;

        @RequestMapping("/new_employee", method=RequestMethod.GET)
        public ModelAndView showEmployeeForm(){
          String position = webRequest.getParameter("position");

          Employee employee = (EmployeeService)appContext.getBean(position);
          //Put position to session
           session.setAttribute("position", position);
                return new ModelAndView("new_employee","employee", employee);
        }

        @RequestMapping("/create", method=RequestMethod.POST)
        public ModelAndView createEmployee() {

           //Get position from session and then getBean
           String position = session.getAttribute("position");
           EmployeeService empService = (EmployeeService)appContext.getBean(position);

           empService.create();
        }
    }

（1）创建员工界面或抽象类类型

@Component
public class Manager implements Employee {
 //define props
}

（2）创建经理、服务员、厨师类（所有工具/扩展员工类型）

（2）员工服务界面：

public interface EmployeeService {
   public void create();
}

@Service("WaiterService")
public class WaiterService extends EmployeeService {
   public void create(Waiter waiter) {
     //add Waiter save logic
   }
}

@Service("ChefService")
public void create(Chef chef) {
      //add Chef save logic
   }
}

    @Controller
    public class EmployeeController {

        @Autowired
        private ApplicationContext appContext;

        @RequestMapping("/new_employee", method=RequestMethod.GET)
        public ModelAndView showEmployeeForm(){
          String position = webRequest.getParameter("position");

          Employee employee = (EmployeeService)appContext.getBean(position);
          //Put position to session
           session.setAttribute("position", position);
                return new ModelAndView("new_employee","employee", employee);
        }

        @RequestMapping("/create", method=RequestMethod.POST)
        public ModelAndView createEmployee() {

           //Get position from session and then getBean
           String position = session.getAttribute("position");
           EmployeeService empService = (EmployeeService)appContext.getBean(position);

           empService.create();
        }
    }

**ManagerService类：**

@Service("ManagerService")
public class ManagerService extends EmployeeService {
   public void create(Manager manager) {
      //add Manager save logic
   }
}

服务员服务类：

public interface EmployeeService {
   public void create();
}

@Service("WaiterService")
public class WaiterService extends EmployeeService {
   public void create(Waiter waiter) {
     //add Waiter save logic
   }
}

@Service("ChefService")
public void create(Chef chef) {
      //add Chef save logic
   }
}

    @Controller
    public class EmployeeController {

        @Autowired
        private ApplicationContext appContext;

        @RequestMapping("/new_employee", method=RequestMethod.GET)
        public ModelAndView showEmployeeForm(){
          String position = webRequest.getParameter("position");

          Employee employee = (EmployeeService)appContext.getBean(position);
          //Put position to session
           session.setAttribute("position", position);
                return new ModelAndView("new_employee","employee", employee);
        }

        @RequestMapping("/create", method=RequestMethod.POST)
        public ModelAndView createEmployee() {

           //Get position from session and then getBean
           String position = session.getAttribute("position");
           EmployeeService empService = (EmployeeService)appContext.getBean(position);

           empService.create();
        }
    }

ChefService类：

public interface EmployeeService {
   public void create();
}

@Service("WaiterService")
public class WaiterService extends EmployeeService {
   public void create(Waiter waiter) {
     //add Waiter save logic
   }
}

@Service("ChefService")
public void create(Chef chef) {
      //add Chef save logic
   }
}

    @Controller
    public class EmployeeController {

        @Autowired
        private ApplicationContext appContext;

        @RequestMapping("/new_employee", method=RequestMethod.GET)
        public ModelAndView showEmployeeForm(){
          String position = webRequest.getParameter("position");

          Employee employee = (EmployeeService)appContext.getBean(position);
          //Put position to session
           session.setAttribute("position", position);
                return new ModelAndView("new_employee","employee", employee);
        }

        @RequestMapping("/create", method=RequestMethod.POST)
        public ModelAndView createEmployee() {

           //Get position from session and then getBean
           String position = session.getAttribute("position");
           EmployeeService empService = (EmployeeService)appContext.getBean(position);

           empService.create();
        }
    }

（3）控制器类方法：

public interface EmployeeService {
   public void create();
}

@Service("WaiterService")
public class WaiterService extends EmployeeService {
   public void create(Waiter waiter) {
     //add Waiter save logic
   }
}

@Service("ChefService")
public void create(Chef chef) {
      //add Chef save logic
   }
}

    @Controller
    public class EmployeeController {

        @Autowired
        private ApplicationContext appContext;

        @RequestMapping("/new_employee", method=RequestMethod.GET)
        public ModelAndView showEmployeeForm(){
          String position = webRequest.getParameter("position");

          Employee employee = (EmployeeService)appContext.getBean(position);
          //Put position to session
           session.setAttribute("position", position);
                return new ModelAndView("new_employee","employee", employee);
        }

        @RequestMapping("/create", method=RequestMethod.POST)
        public ModelAndView createEmployee() {

           //Get position from session and then getBean
           String position = session.getAttribute("position");
           EmployeeService empService = (EmployeeService)appContext.getBean(position);

           empService.create();
        }
    }

备注：我添加了具有不同EmployeeService类型的服务层 为了获得更多的灵活性，但这取决于您使用它（按原样）或 这并不取决于create（）逻辑的复杂程度 不同的员工类型

更新： 如果用户希望添加新类型的员工，则不进行编程就无法创建新类型的员工？

---

上述设计遵循流行的OOP，即我们应该能够在不修改现有类的情况下添加新类（新员工类型或新功能）。因此，您可以在不修改现有类别的情况下添加任意数量的新员工类型。

谢谢！我想在这里实现多态性，而不是开关块。。但没想到会将其移动到服务层！但是你不觉得新员工（）在这里有点多余吗。。。在showEmployeeForm（）中？由于我将从WebRequest对象中检索所有请求参数以从头构建后代，所以我根本不需要员工模型，对吗？我已经修改了上述代码，您现在可以参考它，具体的服务层完全是可选的是的，但直觉上我认为员工应该是抽象的。我们无法实例化。。。这一事实打破了Spring的注入逻辑。还有一件事，如果用户想要添加新类型的Employee，不编程就不可能创建类型……是的，Employee应该是接口或抽象类型，Spring容器应该检测到它（标记为@Component）（为您更新上述答案）