mybatis 为什么会有这种情况

Question

这是我从其他地方拿来改的代码

原来的结构是这样的 可以正常运行
（忽略报红，实际是可以正常运行的）

但是我模仿原来的，写了一个新的，ProblemToSolve 。
结果现在原来本身是可以运行的，比如manager都有错误了

错误如下

以下是我模仿添加的代码

ProblemToSolve.java

package org.electric.model;

import com.baomidou.mybatisplus.annotation.TableField;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import lombok.ToString;
import org.springframework.web.multipart.MultipartFile;

/**
 * 待解决的问题
 */
@Data @AllArgsConstructor @NoArgsConstructor @ToString
public class ProblemToSolve {
    private String id;
    private String problemOutline;
    private String problemDescription;
    private String otherInformation;
    private String problemClassification;
    private String problemState;
    private String deadline;
    private String presenter;
    private String personInCharge;

    @TableField(exist = false)
    private MultipartFile file;
}

ProblemToSolveController.java

package org.electric.controller;

import cn.hutool.core.util.IdUtil;
import com.baomidou.mybatisplus.core.metadata.IPage;
import lombok.extern.log4j.Log4j2;
import org.electric.model.ProblemToSolve;
import org.electric.service.ProblemToSolveService;
import org.electric.utils.Result;
import org.electric.utils.UploadUtil;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.multipart.MultipartFile;

import javax.annotation.Resource;
import javax.servlet.http.HttpServletRequest;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Map;

@CrossOrigin(allowCredentials="true", allowedHeaders="*", methods={RequestMethod.GET,RequestMethod.POST}, origins="*")
@RestController
@Log4j2
public class ProblemToSolveController extends UploadUtil {
    @Value("${spring.servlet.upload.drive.letter}")
    private String driveLetter;
    @Value("${spring.servlet.upload.base-path}")
    private String uploadPath;

    @Resource
    private ProblemToSolveService problemToSolveService;

    @GetMapping("/admin/problem_to_solve/list/{currentPage}/{pageSize}")
    public Result<IPage<Map<String, String>>> listByPage(@PathVariable Integer currentPage, @PathVariable Integer pageSize, HttpServletRequest request){
        IPage<Map<String, String>> result = problemToSolveService.listByPage(currentPage,pageSize,getParameters(request));
        return new Result<>(200,result);
    }
    @PostMapping("/admin/problem_to_solve/save")
    public Result<String> save(ProblemToSolve problemToSolve){
        String id = IdUtil.simpleUUID();
        problemToSolve.setId(id);
        boolean result = problemToSolveService.save(problemToSolve);
        return new Result<>(result?200:400,result?"添加成功！":"添加失败！");
    }

    @GetMapping("/admin/problem_to_solve/get/{id}")
    public Result<ProblemToSolve> getById(@PathVariable String id){
        ProblemToSolve problemToSolve = problemToSolveService.getById(id);
        return new Result<>(200,problemToSolve);
    }
    @PostMapping("/admin/problem_to_solve/update")
    public Result<String> update(ProblemToSolve problemToSolve, MultipartFile file){
        if(null!=file&&(!file.isEmpty())){
            //String head = fileUpload(file,"head",problemToSolve.getHead(),problemToSolve.getId());
            //problemToSolve.setHead(head);
        }
        boolean result = problemToSolveService.updateById(problemToSolve);
        return new Result<>(result?200:400,result?"修改成功！":"修改失败！");
    }

    @GetMapping("/admin/problem_to_solve/delete/{id}")
    public Result<String> delete(@PathVariable String id){
        boolean result = problemToSolveService.removeById(id);
        return new Result<>(result?200:400,result?"删除成功！":"删除失败！");
    }
    private Map<String, String> getParameters(HttpServletRequest request){
        Map<String, String> params = new HashMap<>();
        Enumeration<String> paramNames = request.getParameterNames();
        while (paramNames.hasMoreElements()) {
            String paramName = paramNames.nextElement();
            String[] paramValues = request.getParameterValues(paramName);
            if (paramValues.length == 1) {
                String paramValue = paramValues[0];
                if (paramValue.length() != 0) {
                    params.put(paramName, paramValue);
                }
            }
        }
        return params;
    }
}

ProblemToSolveMapper.java

package org.electric.mapper;

import com.baomidou.mybatisplus.core.conditions.Wrapper;
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.baomidou.mybatisplus.core.metadata.IPage;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Param;
import org.electric.model.ProblemToSolve;

import java.util.List;
import java.util.Map;
@Mapper
public interface ProblemToSolveMapper extends BaseMapper<ProblemToSolve> {
    Page<Map<String, String>> listByPage(IPage<Map<String, String>> page, @Param("ew") Wrapper<Map<String, String>> queryWrapper);

    List<Map<String, String>> listAll();

    List<Map<String,String>> export();

    Integer getCount(@Param("ew")Wrapper<Map<String, String>> queryWrapper);

}

ProblemToSolveService

package org.electric.service;

import com.baomidou.mybatisplus.core.metadata.IPage;
import com.baomidou.mybatisplus.extension.service.IService;
import org.electric.model.ProblemToSolve;

import java.util.List;
import java.util.Map;

public interface ProblemToSolveService extends IService<ProblemToSolve> {
    IPage<Map<String, String>> listByPage(Integer currentPage, Integer pageSize, Map<String, String> params);

    List<Map<String, String>> listAll();

    List<Map<String,String>> export();

    Integer getCount(Map<String, String> params);



}

ProblemToSolveServiceImpl

package org.electric.service.impl;

import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.baomidou.mybatisplus.core.metadata.IPage;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import org.electric.mapper.ProblemToSolveMapper;
import org.electric.model.ProblemToSolve;
import org.electric.service.ProblemToSolveService;
import org.springframework.stereotype.Service;

import javax.annotation.Resource;
import java.util.List;
import java.util.Map;
@Service
public class ProblemToSolveServiceImpl extends ServiceImpl<ProblemToSolveMapper, ProblemToSolve>
        implements ProblemToSolveService {
    @Resource
    private ProblemToSolveMapper problemToSolveMapper;
    @Override
    public IPage<Map<String, String>> listByPage(Integer currentPage, Integer pageSize, Map<String, String> params) {
        IPage<Map<String, String>> page = new Page<>(currentPage, pageSize);
        QueryWrapper<Map<String, String>> wrapper = new QueryWrapper<>();
        for(Map.Entry<String,String> entry : params.entrySet()){
            wrapper.like(entry.getKey(),null==entry.getValue()?"":entry.getValue());
        }
        return problemToSolveMapper.listByPage(page, wrapper);
    }

    @Override
    public List<Map<String, String>> listAll() {
        return problemToSolveMapper.listAll();
    }

    @Override
    public List<Map<String, String>> export() {
        return null;
    }

    @Override
    public Integer getCount(Map<String, String> params) {
        QueryWrapper<Map<String, String>> wrapper = new QueryWrapper<>();
        for(Map.Entry<String,String> entry : params.entrySet()){
            wrapper.eq(entry.getKey(),null==entry.getValue()?"":entry.getValue());
        }
        return problemToSolveMapper.getCount(wrapper);
    }

}

ProblemToSolveMapper.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">

<mapper namespace="org.electric.mapper.ProblemToSolveMapper">
    <select id="listByPage" resultMap="java.util.Map">
        SELECT id,problem_outline,problem_description,problem_classification,problem_state,deadline,presenter,person_in_charge,other_information
        FROM problem_to_solve
        <where>
            ${ew.sqlSegment}
        </where>
        order by deadline DESC
    </select>

    <select id="listAll" resultType="java.util.Map">
        SELECT * FROM problem_to_solve
        order by deadline DESC
    </select>
</mapper>

在我没有添加这些仿写代码之前，运行时完全正常的，但是添加了之后，原来可以正常使用的功能也无法使用了，报我开头的错，我看了一天还是没有头绪。请大lao们帮忙看看。

Answer 1

mapper里第一个select语句，后面的返回应该是resultType，而不是resultMap