Spring-无法将java.lang.String类型的属性值转换为所需类型

我正在为春季的住房协会做一个项目

当我试图将一个对象添加到我的公寓列表时，我得到一个错误，该错误以某种方式写在页面上：

公寓与一幢大楼有许多联系

公寓管理员：

package pl.dmcs.spoldzielnia.controllers;

import java.util.Map;

import javax.servlet.http.HttpServletRequest;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.validation.BindingResult;
import org.springframework.web.bind.ServletRequestUtils;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.SessionAttributes;
import org.springframework.web.servlet.ModelAndView;

import pl.dmcs.spoldzielnia.domain.Apartment;
import pl.dmcs.spoldzielnia.service.ApartmentService;
import pl.dmcs.spoldzielnia.service.BuildingService;




@Controller
@SessionAttributes
public class ApartmentController {

    @Autowired
    ApartmentService apartmentService;



    @Autowired
    BuildingService buildingService;



    @RequestMapping("admin/apartment")
    public String listApartment(Map<String, Object> map, HttpServletRequest request) {

        int apartmentId = ServletRequestUtils.getIntParameter(request, "apartmentId" , -1);

        if (apartmentId > 0)
        {   
            Apartment apartment = apartmentService.getApartment(apartmentId);

            apartment.setBuilding(buildingService.getBuilding(apartmentService.getApartment(apartmentId).getBuilding().getId()));


            map.put("selectedBuilding", apartmentService.getApartment(apartmentId).getBuilding().getId());
            map.put("apartment", apartment);
        }
        else
           map.put("apartment", new Apartment());   


        map.put("buildingList", buildingService.listBuilding());
        map.put("apartmentList", apartmentService.listApartment());

        return "apartment";
    }

   @RequestMapping(value = "admin/addApartment", method = RequestMethod.POST)
   public String addContact(@ModelAttribute("apartment") Apartment apartment, BindingResult result, 
           HttpServletRequest request, Map<String, Object> map) {



       if (result.getErrorCount()==0)
       {
           if (apartment.getId()==0)
           {

               if (apartment.getBuilding().getId() > 0)
                   apartment.setBuilding(buildingService.getBuilding(apartment.getBuilding().getId()));
               apartmentService.addApartment(apartment);
           }
           else
           {

               apartmentService.editApartment(apartment);
           }


           return "redirect:/admin/apartment.html";
       }


       map.put("buildingList", buildingService.listBuilding());
       map.put("apartmentList", apartmentService.listApartment());
       return "apartment";
   }

   @RequestMapping("admin/delete/apartment/{apartmentId}")
   public String deleteApartment(@PathVariable("apartmentId") Integer apartmentId) {
       apartmentService.removeApartment(apartmentId);

       return "redirect:/admin/apartment.html";
   }
//   @RequestMapping("/apartment")
//   public ModelAndView showContacts() {
//        
//       return new ModelAndView("apartment", "command", new Apartment());
//   }

楼宇服务实施：

package pl.dmcs.spoldzielnia.service;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.security.crypto.bcrypt.BCryptPasswordEncoder;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import pl.dmcs.spoldzielnia.dao.BuildingDAO;
import pl.dmcs.spoldzielnia.domain.Building;
import pl.dmcs.spoldzielnia.domain.Building;

@Service
@Transactional
public class BuildingServiceImpl implements BuildingService{

    @Autowired
    BuildingDAO buildingDAO;

    @Transactional
    public void addBuilding(Building building) {


        buildingDAO.addBuilding(building);
    }

    @Transactional
    public List<Building> listBuilding() {

        return buildingDAO.listBuilding();
    }

    @Transactional
    public Building getBuilding(int id) {
        return buildingDAO.getBuilding(id);
    }

    @Transactional
    public void removeBuilding(int id) {
        buildingDAO.removeBuilding(id);
    }

    @Transactional
    public void editBuilding(Building building) {

        buildingDAO.editBuilding(building);
    }
}

包pl.dmcs.spoldzielnia.service；
导入java.util.List；
导入org.springframework.beans.factory.annotation.Autowired；
导入org.springframework.security.crypto.bcrypt.BCryptPasswordEncoder；
导入org.springframework.stereotype.Service；
导入org.springframework.transaction.annotation.Transactional；
导入pl.dmcs.spoldzielnia.dao.BuildingDAO；
导入pl.dmcs.spoldzielnia.domain.Building；
导入pl.dmcs.spoldzielnia.domain.Building；
@服务
@交易的
公共类BuildingServiceImpl实现BuildingService{
@自动连线
楼道楼道；
@交易的
公共建筑（建筑）{
楼道。加楼（楼）；
}
@交易的
公共建筑清单（）{
返回buildingDAO.listBuilding（）；
}
@交易的
公共建筑（内部id）{
返回buildingDAO.getBuilding（id）；
}
@交易的
公共无效移除建筑（内部id）{
buildingDAO.removeBuilding（id）；
}
@交易的
公共建筑（建筑）{
楼道。编辑楼（楼）；
}
}

---

您能帮我解决我的问题吗？

问题是您假设Spring MVC将能够根据传递的数据填充公寓对象。从表单上看，建筑编号是12，这可能是数据库中建筑的唯一标识符，但是Spring MVC如何知道如何进入数据库，检索适当的建筑对象并将其放入公寓对象

请记住，通过SpringMVC参数映射的对象是常规Java POJO，而不是Hibernate连接的实体。因此，当映射发生时，SpringMVC试图将building类型的building属性中的“12”放入POJO中（这解释了您得到的错误）

您有两个选择： 首先，您可以注册自定义格式化程序，该格式化程序将使用传递的id从数据库检索建筑：

import org.springframework.core.convert.converter.Converter;

public class BuildingIdToBuildingConverter implements Converter<String, Building> {

    private BuildingService buildingService;

    public BuildingIdToBuildingConverter(BuildingService buildingService) {
        this.buildingService = buildingService;
    }

    @Override
    public Building convert (String id) {
            return buildingService.getBuilding(id);
    }
}

其次，通过在单独的参数中发送建筑id手动执行此操作：

@RequestMapping(value = "admin/addApartment", method = RequestMethod.POST)
   public String addContact(@ModelAttribute("apartment") Apartment apartment, @RequestParam("buildingId") String buildingId, BindingResult result, HttpServletRequest request, Map<String, Object> map) {
       if (result.getErrorCount()==0){
           if (apartment.getId()==0){
               apartment.setBuilding(buildingService.getBuilding(buildingId));
               apartmentService.addApartment(apartment);
            }
        }
       else{
           apartmentService.editApartment(apartment);
       }

       return "redirect:/admin/apartment.html";
   }

   map.put("buildingList", buildingService.listBuilding());
   map.put("apartmentList", apartmentService.listApartment());
   return "apartment";
}

@RequestMapping（value=“admin/addpartment”，method=RequestMethod.POST）
公共字符串addContact（@ModelAttribute（“公寓”）公寓、@RequestParam（“buildingId”）字符串buildingId、BindingResult、HttpServletRequest请求、映射）{
if（result.getErrorCount（）==0）{
if（公寓.getId（）==0）{
公寓.setBuilding（buildingService.getBuilding（buildingId））；
公寓服务。公寓（公寓）；
}
}
否则{
公寓服务。编辑公寓（公寓）；
}
返回“重定向：/admin/plantment.html”；
}
put（“buildingList”，buildingService.listBuilding（））；
put（“apartmentList”，apartmentService.List公寓（））；
返回“公寓”；
}

---

并相应地更改HTML以发送buildingId值。

问题在于您假设Spring MVC将能够根据传递的数据填充公寓对象。从表单上看，建筑编号是12，这可能是数据库中建筑的唯一标识符，但是Spring MVC如何知道如何进入数据库，检索适当的建筑对象并将其放入公寓对象

请记住，通过SpringMVC参数映射的对象是常规Java POJO，而不是Hibernate连接的实体。因此，当映射发生时，SpringMVC试图将building类型的building属性中的“12”放入POJO中（这解释了您得到的错误）

您有两个选择： 首先，您可以注册自定义格式化程序，该格式化程序将使用传递的id从数据库检索建筑：

import org.springframework.core.convert.converter.Converter;

public class BuildingIdToBuildingConverter implements Converter<String, Building> {

    private BuildingService buildingService;

    public BuildingIdToBuildingConverter(BuildingService buildingService) {
        this.buildingService = buildingService;
    }

    @Override
    public Building convert (String id) {
            return buildingService.getBuilding(id);
    }
}

其次，通过在单独的参数中发送建筑id手动执行此操作：

@RequestMapping(value = "admin/addApartment", method = RequestMethod.POST)
   public String addContact(@ModelAttribute("apartment") Apartment apartment, @RequestParam("buildingId") String buildingId, BindingResult result, HttpServletRequest request, Map<String, Object> map) {
       if (result.getErrorCount()==0){
           if (apartment.getId()==0){
               apartment.setBuilding(buildingService.getBuilding(buildingId));
               apartmentService.addApartment(apartment);
            }
        }
       else{
           apartmentService.editApartment(apartment);
       }

       return "redirect:/admin/apartment.html";
   }

   map.put("buildingList", buildingService.listBuilding());
   map.put("apartmentList", apartmentService.listApartment());
   return "apartment";
}

@RequestMapping（value=“admin/addpartment”，method=RequestMethod.POST）
公共字符串addContact（@ModelAttribute（“公寓”）公寓、@RequestParam（“buildingId”）字符串buildingId、BindingResult、HttpServletRequest请求、映射）{
if（result.getErrorCount（）==0）{
if（公寓.getId（）==0）{
公寓.setBuilding（buildingService.getBuilding（buildingId））；
公寓服务。公寓（公寓）；
}
}
否则{
公寓服务。编辑公寓（公寓）；
}
返回“重定向：/admin/plantment.html”；
}
put（“buildingList”，buildingService.listBuilding（））；
put（“apartmentList”，apartmentService.List公寓（））；
返回“公寓”；
}

---

并相应地更改HTML以发送buildingId值。

附加异常日志。附加异常日志。