spring mvc - 错误空指针异常

Question

我尝试将数据插入数据库，但出现内部服务器错误java.lang.NullPointerException

我创建了自己的 Spring MVC，可能它与其他的不同

我认为错误的发生是因为模型没有从正文中获取数据，因此在调用保存方法时发生空指针异常错误

这里是代码

控制器

@RestController
public class SellerController {

@Autowired
SellerService service;

@RequestMapping(method = RequestMethod.POST, path = "sellers/register",
            consumes = "application/json", produces = "application/json")
public ResponsePost postSellerRegister(@RequestBody SellerPost model){

    ResponsePost response = new ResponsePost();
    model.getSlrNim();
    model.getStdId();
    model.getSlrName();
    model.getSlrPass();
    model.getSlrEmail();
    model.getSlrContact();
    model.getSlrGender();
    try{
            service.connectToDatabase();
            Result<Integer> result = service.save(model);
            response.setStatus(result.getStatus());
            response.setId(result.getModel());
            service.closeConnection();
    }catch(SQLException e) {
            response.setStatus(StateCons.SQL_EXCEPTION);
    }
    return response;
  }
}

服务

@Service
public class SellerService extends BaseService implements BaseDao<SellerPost, SellerGet, SellerGet> {

public SellerService(){

}

@Override
public Result<Integer> save(SellerPost model){

    Result<Integer> result = new Result();
    if(getDatabase().getResult() == StateCons.SUCCESS){
            try{
                           String sql = "INSERT INTO seller (slr_nim, slr_name, std_id, slr_gender, slr_email, slr_contact, slr_pass) VALUES ('"+ model.getSlrNim() +"', '"+ model.getSlrName() + "', '"+ model.getStdId() +"', "+ model.getSlrGender() +", '"+ model.getSlrEmail() +"', '" + model.getSlrContact() +"', '"+ model.getSlrPass() +"')";
                            setResultSet(getDatabase().executeQuery(sql));
                            if(getResultSet().next()) {
                                    result.setModel(new Integer(getResultSet().getInt("slr_nim")));
                                    result.setStatus(StateCons.SUCCESS);
                            }else{
                                    result.setStatus(StateCons.FAILED);
                            }
                    getResultSet().close();
            }catch(SQLException e) {
                    result.setStatus(StateCons.NO_RECORD);
            }
    }else{
            result.setStatus(StateCons.FAILED);
    }
    return result;
 }
}

DAO

package id.ceban.dao;

import java.util.List;
import id.ceban.model.Result;

public interface BaseDao<P, G, GD> {

public Result<Integer> save(P model);

public Result<Boolean> delete(int modelId);

public Result<Boolean> update(P model, int modelId);

public Result<GD> get(int modelId);

public Result<List<G> > getList(String search_query, String field, String sort, int page, int limit);

public Result<Integer> count(int modelId);

}

错误

Answer 1

在控制器中，您不应获得SellerService 的新实例，而应使用@Autowired。你可以尝试替换这个：

SellerService service = new SellerService();

为此：

@Autowired
SellerService service;

并且SellerService类应该在类定义之前有@Service注解：

@Service
public class SellerService extends BaseService implements BaseDao<SellerPost, SellerGet, SellerGet> {
//...
}