<dependency>
      <groupId>com.alibaba</groupId>
      <artifactId>easyexcel</artifactId>
      <version>2.2.7</version>
    </dependency>

@PostMapping("plUpdate")
  public R plUpdate(@RequestParam("filename") MultipartFile file) throws IOException {
    //String Originalfilename = file.getOriginalFilename();
    // String fileName = file.getName();
   // System.out.println("orname="+Originalfilename+";"+"filename"+file.getName());

    // 獲取文件全名
    String fileName = file.getOriginalFilename();
     //設(shè)置文件路徑
    String templatePath = "G:/excel/";
    File dest0 = new File(templatePath);
    File dest = new File(dest0, fileName);
    //文件上傳-覆蓋
    try {
      // 檢測是否存在目錄
      if (!dest0.getParentFile().exists()) {
        dest0.getParentFile().mkdirs();
        //檢測文件是否存在
      }
      if (!dest.exists()) {
        dest.mkdirs();
      }
      file.transferTo(dest);
    } catch (Exception e) {
      return R.error();
    }

    String finameUrl = templatePath+fileName;
    ExcelReader excelReader = null;
    try {
    //TeacherExcel.class對應的是和模板一樣的實體類，
    //eduTeacherService對應持久層的接口
      excelReader = EasyExcel.read(finameUrl, TeacherExcel.class, new DemoDataListener(eduTeacherService)).build();
      ReadSheet readSheet = EasyExcel.readSheet(0).build();
      excelReader.read(readSheet);
    } finally {

      if (excelReader != null) {
        // 這里千萬別忘記關(guān)閉，讀的時候會創(chuàng)建臨時文件，到時磁盤會崩的
        excelReader.finish();
      }
    }
    return R.ok();
  }

package com.atguigu.excel;

import com.alibaba.excel.context.AnalysisContext;
import com.alibaba.excel.event.AnalysisEventListener;
import com.atguigu.eduservice.entity.EduTeacher;
import com.atguigu.eduservice.entity.vo.TeacherExcel;
import com.atguigu.eduservice.service.EduTeacherService;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.util.ArrayList;
import java.util.List;

// 有個很重要的點 DemoDataListener 不能被spring管理，要每次讀取excel都要new,然后里面用到spring可以構(gòu)造方法傳進去
public class DemoDataListener extends AnalysisEventListener<TeacherExcel> {
  private static final Logger LOGGER = LoggerFactory.getLogger(DemoDataListener.class);
  //這里寫持久層的類
  private EduTeacherService eduTeacherService;
  
  /**

   * 如果使用了spring,請使用這個構(gòu)造方法。每次創(chuàng)建Listener的時候需要把spring管理的類傳進來

   *

   * @param eduTeacherService

   */

  public DemoDataListener( EduTeacherService eduTeacherService) {
        //進行持久層的類
    this.eduTeacherService = eduTeacherService;

  }
  

  /**
   * 每隔5條存儲數(shù)據(jù)庫，實際使用中可以3000條，然后清理list ，方便內(nèi)存回收
   */
  private static final int BATCH_COUNT = 5;
  List<TeacherExcel> list = new ArrayList<TeacherExcel>();
  /**
   * 假設(shè)這個是一個DAO，當然有業(yè)務(wù)邏輯這個也可以是一個service。當然如果不用存儲這個對象沒用。
   */
  //private DemoDAO demoDAO;
  public DemoDataListener() {
    // 這里是demo，所以隨便new一個。實際使用如果到了spring,請使用下面的有參構(gòu)造函數(shù)
    //demoDAO = new DemoDAO();
  }
  /**
   * 如果使用了spring,請使用這個構(gòu)造方法。每次創(chuàng)建Listener的時候需要把spring管理的類傳進來
   *
   * @param demoDAO
   */
  /* public DemoDataListener(DemoDAO demoDAO) {
    this.demoDAO = demoDAO;
  }*/
  /**
   * 這個每一條數(shù)據(jù)解析都會來調(diào)用
   *
   * @param data
   *      one row value. Is is same as {@link AnalysisContext#readRowHolder()}
   * @param context
   */
  @Override
  public void invoke(TeacherExcel data, AnalysisContext context) {
    LOGGER.info("解析到一條數(shù)據(jù):{}",data.toString());
    list.add(data);
    // 達到BATCH_COUNT了，需要去存儲一次數(shù)據(jù)庫，防止數(shù)據(jù)幾萬條數(shù)據(jù)在內(nèi)存，容易OOM

  }
  /**
   * 所有數(shù)據(jù)解析完成了 都會來調(diào)用
   *
   * @param context
   */
  @Override
  public void doAfterAllAnalysed(AnalysisContext context) {
    // 這里也要保存數(shù)據(jù)，確保最后遺留的數(shù)據(jù)也存儲到數(shù)據(jù)庫
    saveData();
    LOGGER.info("所有數(shù)據(jù)解析完成！");
  }
  /**
   * 加上存儲數(shù)據(jù)庫
   */
  private void saveData() {
    LOGGER.info("{}條數(shù)據(jù)，開始存儲數(shù)據(jù)庫！", list.size());
    //因為我excel模板的實體和插入數(shù)據(jù)庫實體的類不一樣，所以需要進行轉(zhuǎn)化

    for (int i =0;i<list.size();i++ ){
      EduTeacher teacher = new EduTeacher();
      teacher.setLevel(list.get(i).getLevel());
      teacher.setCareer(list.get(i).getCareer());
      teacher.setName(list.get(i).getName());
      teacher.setSort(list.get(i).getSort());
      teacher.setIntro(list.get(i).getIntro());
      boolean save = eduTeacherService.save(teacher);
      if (save){
        System.out.println("第"+i+"添加成功");
      }
    }
  } 
}

@ExcelProperty(value = “講師簡介”,index = 1)
private String intro;

package com.atguigu.eduservice.config;

import com.alibaba.excel.EasyExcel;
import com.alibaba.excel.support.ExcelTypeEnum;
import com.alibaba.excel.write.metadata.style.WriteCellStyle;
import com.alibaba.excel.write.style.HorizontalCellStyleStrategy;
import org.apache.poi.ss.usermodel.HorizontalAlignment;

import javax.servlet.http.HttpServletResponse;
import java.io.OutputStream;
import java.net.URLEncoder;
import java.util.List;

/**
 * @author linjiazeng
 * @version 1.0
 * @date 2020/12/28 22:29
 **/
public class ExcelUtil {

  /**
   * 導出
   * @param response
   * @param data
   * @param fileName
   * @param sheetName
   * @param clazz
   * @throws Exception
   */
  public static void writeExcel(HttpServletResponse response, List<? extends Object> data, String fileName, String sheetName, Class clazz) throws Exception {
    //表頭樣式
    WriteCellStyle headWriteCellStyle = new WriteCellStyle();
    //設(shè)置表頭居中對齊
    headWriteCellStyle.setHorizontalAlignment(HorizontalAlignment.CENTER);
    //內(nèi)容樣式
    WriteCellStyle contentWriteCellStyle = new WriteCellStyle();
    //設(shè)置內(nèi)容靠左對齊
    contentWriteCellStyle.setHorizontalAlignment(HorizontalAlignment.LEFT);
    HorizontalCellStyleStrategy horizontalCellStyleStrategy = new HorizontalCellStyleStrategy(headWriteCellStyle, contentWriteCellStyle);
    EasyExcel.write(getOutputStream(fileName, response), clazz).excelType(ExcelTypeEnum.XLSX).sheet(sheetName).registerWriteHandler(horizontalCellStyleStrategy).doWrite(data);
  }
  private static OutputStream getOutputStream(String fileName, HttpServletResponse response) throws Exception {
    fileName = URLEncoder.encode(fileName, "UTF-8");
    response.setContentType("application/vnd.ms-excel");
    response.setCharacterEncoding("utf8");
    response.setHeader("Content-Disposition", "attachment;filename=" + fileName + ".xlsx");
    response.addHeader("Access-Control-Expose-Headers", "Content-disposition");

    return response.getOutputStream();
  }
}

 /*下載模板*/
  @GetMapping("/download/template")
  public void downloadTemplate(HttpServletResponse response){
    String fileName = "導入講師模板";
    String sheetName="導入講師模板";
    List<TeacherExcel> teacherExcelList = new ArrayList<>();
    TeacherExcel teacherExcel = new TeacherExcel();
    teacherExcel.setName("ljz");
    teacherExcel.setIntro("清華畢業(yè)，高材生");
    teacherExcel.setCareer("資深講師");
    teacherExcel.setSort(1);
    teacherExcel.setLevel(1);
    teacherExcelList.add(teacherExcel);
    try {
      //TeacherExcel.class對應你的模板類
      //teacherExcelList模板的例子
      //也可以使用這種方式導出你查詢出數(shù)據(jù)excel文件
      ExcelUtil.writeExcel(response,teacherExcelList,fileName,sheetName,TeacherExcel.class);
    } catch (Exception e) {
      System.out.println(e.getCause());

    }
  }