一、首先在前端写一个上传组件。

<template><!-- 文件上传 --><el-upload class="upload-demo" drag action="" :on-change="onChange" :auto-upload="false"><el-icon class="el-icon--upload"><upload-filled /></el-icon><div class="el-upload__text">Drop file here or <em>click to upload</em></div></el-upload>
</template><script lang="ts" setup>
import { ref } from "vue";
import { uploadApi } from "@/api/index";
import { ElMessage} from "element-plus";
//定义文件上传的函数
const onChange = (file: any, _uploadFiles: any) => {let reader = new FileReader();reader.readAsDataURL(file.raw);reader.onload = (f) => {callUploadApi(file.name, f.target?.result);};
};
//文件上传的函数
const callUploadApi = (name: any, base64: any) => {uploadApi.uploadExcel.call({ name, base64 }).then((res: any) => {ElMessage.success("上传成功");});
};
</script>

封装一个Api

请求配置：uploadApi.ts

 uploadExcel: {name: "上传文件",url: "/api/uploade/excel",call: async function name(params: any) {return await http.post(this.url, params);},},

二、后端代码实现

准备工作：1、一个与你上传数据相对于的实体类；

                  2、定义一个上传信息对象；

 实体类：为了方便演示我就定义两个字段，以供参考：

@Data
public class Person {private String name;private Integer age;
}

上传信息对象：

@Data
public class UploadInfo {private String name;private String base64;
}

Controller层代码：

/** Copyright (c) 2020, 2024,  All rights reserved.**/
package com.by.upload;import cn.hutool.core.codec.Base64;
import cn.hutool.core.date.StopWatch;
import cn.hutool.core.util.StrUtil;
import cn.hutool.poi.excel.ExcelReader;
import cn.hutool.poi.excel.ExcelUtil;
import cn.hutool.poi.excel.ExcelWriter;
import com.by.dao.PersonMapper;
import com.by.model.FileInfo;
import com.by.model.Upload;
import com.by.service.UploadService;
import org.apache.ibatis.session.ExecutorType;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletResponse;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.util.List;
import java.util.stream.Collectors;/*** <p>Project: wms-root - Upload</p>* <p>Powered by scl On 2024-02-29 19:07:05</p>* <p>描述：<p>** @author 孙臣龙 [1846080280@qq.com]* @version 1.0* @since 17*/
@RestController
@RequestMapping("/api/uploade")
public class UploadExcel {@Autowiredprivate SqlSessionFactory sqlSessionFactory;@Autowiredprivate PersonMapper personMapper;@Autowiredprivate UploadService uploadService;/*** 导入excle* @param uploadInfo* @return* @throws Exception*/@PostMapping("/excel")public String upload(@RequestBody Upload uploadInfo) throws Exception {String name = uploadInfo.getName();String base64 = uploadInfo.getBase64();String[] strArray = StrUtil.splitToArray(base64, "base64,");byte[] bytes = Base64.decode(strArray[1]);//用于创建一个基于字节数组的输入流。它允许你从一个字节数组中读取数据。ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(bytes);// 使用Hutool读取Excel文件ExcelReader reader = ExcelUtil.getReader(byteArrayInputStream);//将读取到的 reader 转化为 List<Man>集合List<Person> persons = reader.readAll(Person.class);//StopWatch类是 Hutool 工具库中的类,用于测量代码执行时间StopWatch stopWatch = new StopWatch();//读取数据的结束时间同时也是写入数据库的开始时间stopWatch.start();//sqlSessionFactory是通过ioc容器注入的  设置其SqlSession的执行器格式ExecutorType.SIMPLE（默认）SqlSession sqlSession = sqlSessionFactory.openSession(ExecutorType.BATCH);PersonMapper mapper = sqlSession.getMapper(PersonMapper.class);//循环将List<Man>中的数据插入数据库 方法一//for (Person person : persons) {//    PoItemMapper.xml.insert(person);//}//方法二：mapper.insertBatch(persons);sqlSession.commit();stopWatch.stop();sqlSession.close();System.out.println("插入数据库最终的结果为：" + stopWatch.getTotalTimeSeconds());return "ok";}/*** 导出Excel* @param response* @throws IOException*/@GetMapping("/write")public void exportExcel(HttpServletResponse response) throws IOException {// 创建Excel写入器   参数 true 表示追加数据，即在已有的 Excel 文件上追加新数据。如果设为 false，则会覆盖已有的数据。List<Person> person = personMapper.selectAll();// 创建ExcelWriter对象ExcelWriter writer = ExcelUtil.getWriter(true);int i = 0;while (true) {List<Person> list = person.stream().skip(i * 100000).limit(100000).parallel().collect(Collectors.toList());if (list.isEmpty()) {break;}writer.setSheet("person" + i);// 写入表头writer.addHeaderAlias("id", "Id");writer.addHeaderAlias("name", "姓名");writer.addHeaderAlias("age", "年龄");// 写入当前批次的数据writer.write(list, true);i++;}//response为HttpServletResponse对象   设置响应的内容类型为Excel文件response.setContentType("application/xlsx;charset=utf-8");//test.xls是弹出下载对话框的文件名，不能为中文，中文请自行编码//设置响应头，告诉浏览器以附件形式下载文件，文件名为test.xlsx。这样设置可以让浏览器弹出文件下载对话框。response.setHeader("Content-Disposition", "attachment;filename="+"test.xlsx");//获取响应输出流，它是用于将响应的数据发送给客户端的流。ServletOutputStream out = response.getOutputStream();//将Excel数据写入输出流。第二个参数为true表示追加写入，即将数据追加到已有的Excel文件中。writer.flush(out, true);writer.close();//关闭输出流out.close();}
}

dao层代码：

/** Copyright (c) 2020, 2024,  All rights reserved.**/
package com.by.dao;import com.by.upload.Person;
import org.apache.ibatis.annotations.Mapper;import java.util.List;/*** <p>Project: wms-root - PersonMapper</p>* <p>Powered by scl On 2024-03-02 10:51:08</p>* <p>描述：<p>** @author 孙臣龙 [1846080280@qq.com]* @version 1.0* @since 17*/
@Mapper
public interface PersonMapper {void insert(Person person);void insertBatch(List<Person> persons);List<Person> selectAll();}

Mapper.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="com.by.dao.PersonMapper"><!--新增数据--><insert id="insert">insert into person(name,age)values (#{name},#{age})</insert><!-- 批量新增数据 --><insert id="insertBatch" >insert into person(name,age)values<foreach collection="persons" item="entity" separator=",">(#{entity.name},#{entity.age})</foreach></insert><select id="selectAll" resultType="com.by.upload.Person">select * from person</select>
</mapper>

 注意：poi的版本号

<!--poi-->
<dependency><groupId>org.apache.poi</groupId><artifactId>poi-ooxml</artifactId><version>5.0.0</version>
</dependency>

三、文件导出。

前端代码： 

<template><a type="success" href="/api/uploade/write" >导出Excle</a>
</template>