Use hutool to import, export

1. First introduce dependencies

<dependency>
            <groupId>cn.hutool</groupId>
            <artifactId>hutool-all</artifactId>
            <version>5.7.18</version>
        </dependency>
        <dependency>
            <groupId>org.apache.poi</groupId>
            <artifactId>poi-ooxml</artifactId>
            <version>4.1.2</version>
        </dependency>

2, controller class

package com.green.testlocalhost.controller;

import com.green.testlocalhost.common.Exception.BaseException;
import com.green.testlocalhost.service.ExcelService;
import io.swagger.annotations.Api;
import io.swagger.annotations.ApiOperation;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.multipart.MultipartFile;

import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

/**
 * @Author zdj
 * @Date 2022/11/25 16:49
 * @Version 1.0
 */
@Api(tags = "excel管理")
@RestController
@RequestMapping("/excelMgmt")
public class ExcelController {
    
    

    /**
     *  excel服务类
     **/
    @Autowired
    private ExcelService excelService;

    /**
     * 处理用户成绩方法
     * @param file
     * @return
     */
    @RequestMapping(value = "/detalUserGradeData", method = RequestMethod.POST)
    @ApiOperation(value = "处理用户成绩方法", notes = "处理用户成绩方法", httpMethod = "POST")
    public void detalUserGradeData(HttpServletResponse response, @RequestParam(value = "file", required = false) @RequestPart("file") MultipartFile file) throws IOException {
    
    
        if (file.getBytes() == null) {
    
    
            throw new BaseException("处理用户信息", "文件不能为空！", null);
        }
        excelService.detalUserGradeData(file, response);
    }
}

3, server class

package com.green.testlocalhost.service;

import cn.hutool.core.collection.CollUtil;
import cn.hutool.poi.excel.ExcelReader;
import cn.hutool.poi.excel.ExcelUtil;
import cn.hutool.poi.excel.ExcelWriter;
import com.green.testlocalhost.vo.User;
import org.springframework.stereotype.Service;
import org.springframework.util.ObjectUtils;
import org.springframework.web.multipart.MultipartFile;

import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.InputStream;
import java.net.URLEncoder;
import java.util.List;

/**
 * @Author zdj
 * @Date 2022/10/28 17:22
 * @Version 1.0
 */
@Service
public class ExcelService {
    
    

    /**
     * 处理用户成绩方法
     * @param file
     * @return
     */
    public void detalUserGradeData(MultipartFile file, HttpServletResponse response) throws IOException {
    
    
        /********************* 处理excel并封装未集合 *********************/
        // 通过文件获取输入流
        InputStream is = file.getInputStream();
        // 借助hutool读取
        ExcelReader reader = ExcelUtil.getReader(is);
        List<User> userListTemp = reader.read(0, 1, User.class);
        // 创建一个List集合
        List<User> userListResult = CollUtil.newArrayList();
        for (User row : userListTemp) {
    
    
            User user = new User();
            user.setName(row.getName());
            user.setAge(row.getAge());
            user.setChineseGrade(row.getChineseGrade());
            user.setMathGrade(row.getMathGrade());
            userListResult.add(user);
        }

        // 求总成绩
        double chineseSumGrade = userListResult.stream().mapToDouble(User::getChineseGrade).sum();
        double mathSumGrade = userListResult.stream().mapToDouble(User::getMathGrade).sum();
        User user = new User();
        user.setName("总成绩");
        user.setChineseGrade(chineseSumGrade);
        user.setMathGrade(mathSumGrade);
        userListResult.add(user);
        // 到这里，导入就结束了哈，你可以将这个userListResult进行入库处理

        /********************* 将数据导出 *********************/
        String excelName = "处理后的用户信息";
        ExcelWriter writer = null;
        ServletOutputStream out = null;
        try {
    
    
            // 设置数据到输入流
            writer = ExcelUtil.getWriter(true);
            writer.write(userListResult, true);
            // 设置响应头
            response.setContentType("application/vnd.openxmlformats-officedocument.spreadsheetml,sheet;charset=utf-8");
            response.setHeader("Content-Disposition", "attachment;filename=" + URLEncoder.encode(excelName, "UTF-8") + ".xlsx");
            out = response.getOutputStream();
            writer.flush(out, true);
        } catch (Exception e) {
    
    
            e.printStackTrace();
            System.out.println("导出出现异常：" + e.getMessage());
        } finally {
    
    
            // 最后关闭输出流和写入流
            if(!ObjectUtils.isEmpty(writer)) writer.close();
            if(!ObjectUtils.isEmpty(out)) out.close();
        }
    }
}

4. PO class

package com.green.testlocalhost.vo;

import cn.hutool.core.annotation.Alias;
import lombok.Data;

/**
 * @Author zdj
 * @Date 2022/11/25 17:02
 * @Version 1.0
 */
@Data
public class User {
    
    
    @Alias("姓名")
    private String name;

    @Alias("年龄")
    private String age;

    @Alias("语文成绩")
    private Double chineseGrade;

    @Alias("数学成绩")
    private Double mathGrade;
}

5, test

Simple and rude, one step in place (I am lazy here, write the import and export in the same method, just record, use, and partners who need it, just refer to it and package it yourself)