1：导入依赖jar包

 <!-- https://mvnrepository.com/artifact/com.alibaba/easyexcel -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>easyexcel</artifactId>
            <version>2.2.7</version>
        </dependency>

2：需要导出导入的实体类继承BaseRowModel

具体代码:

重点注意（//@Accessors(chain = true)，//@Data：这两个注解不能同时使用，并且实体类的属性要使用驼峰命名）

/**
 *
 * @author MRYIN
 * @since 2021-03-02
 */
//@Data
@EqualsAndHashCode(callSuper = false)
//@Accessors(chain = true)
@ApiModel(value="Task对象", description="")
public class Task extends BaseRowModel implements Serializable {

    private static final long serialVersionUID = 1L;

    @ApiModelProperty(value = "零件编号")
    @TableId(value = "id", type = IdType.ID_WORKER_STR)
    @ExcelProperty(value = "零件编号" , index = 0)
    private String id;

    @ApiModelProperty(value = "装配的单价")
    @ExcelProperty(value = "装配的单价" , index = 1)
    private Integer monovalent;

    @ApiModelProperty(value = "任务负责人")
    @ExcelProperty(value = "任务负责人" , index = 2)
    private String name;

    @ApiModelProperty(value = "装配任务状态")
    @ExcelProperty("装配任务状态")
    private Integer status;

    @ApiModelProperty(value = "接单时间")
    @ExcelProperty("接单时间")
    @TableField(fill = FieldFill.INSERT)
    private Date createTime;

    @ApiModelProperty(value = "计划完成时间")
    @ExcelProperty("计划完成时间")
    private Date finishTime;

    @ApiModelProperty(value = "更新时间")
    @ExcelProperty("更新时间")
    @TableField(fill = FieldFill.INSERT_UPDATE)
    private Date updateTime;

    private Map<Integer, CellStyle> cellStyleMap = new HashMap<Integer,CellStyle>();
    
    `Get、Set`省略、、、、

}

3：编写一个监听类继承AnalysisEventListener并重写其中的方法

具体代码：

/**
 * 监听类，可以自定义
 *
 * @author MRYIN
 * @Created 2021-3-10 22:01:53
 **/
public class ExcelListener extends AnalysisEventListener {

    /**
     * 自定义用于暂时存储data。
     * 可以通过实例获取该值
     */
    private List<Object> datas = new ArrayList<>();

    /**
     * 通过 AnalysisContext 对象还可以获取当前 sheet，当前行等数据
     */
    @Override
    public void invoke(Object object, AnalysisContext context) {
        //数据存储到list，供批量处理，或后续自己业务逻辑处理。
        datas.add(object);
        //根据业务自行 do something
        doSomething();
         /*
         如数据过大，可以进行定量分批处理
         if(datas.size()<=100){
         datas.add(object);
         }else {
         doSomething();
         datas = new ArrayList<Object>();
         }
         */
    }

    /**
     * 根据业务自行实现该方法
     */
    private void doSomething() {
    }

    @Override
    public void doAfterAllAnalysed(AnalysisContext context) {
         /*
         datas.clear();
         解析结束销毁不用的资源
         */
    }

    public List<Object> getDatas() {
        return datas;
    }

    public void setDatas(List<Object> datas) {
        this.datas = datas;
    }
}

4：包含有多种导入导出的工具方法，可自行根据具体要求来选择，其中我只是用到的是导入方法，导出解和LayUI的表格导出使用

具体代码：

/**
 * Excel工具类
 *
 * @@author MRYIN
 *  * @Created 2021-3-10 22:05:53
 **/
public class ExcelUtil {
    /**
     * 读取 Excel(多个 sheet)
     *
     * @param excel 文件
     * @param rowModel 实体类映射，继承 BaseRowModel 类
     * @return Excel 数据 list
     */
    public static List<Object> readExcel(MultipartFile excel, BaseRowModel rowModel) throws ExcelException {
        ExcelListener excelListener = new ExcelListener();
        ExcelReader reader = getReader(excel, excelListener);

        if (reader == null) {
            return null;
        }

        for (Sheet sheet : reader.getSheets()) {
            if (rowModel != null) {
                sheet.setClazz(rowModel.getClass());
            }
            reader.read(sheet);
        }

        return excelListener.getDatas();
    }

    /**
     * 读取某个 sheet 的 Excel
     *
     * @param excel 文件
     * @param rowModel 实体类映射，继承 BaseRowModel 类
     * @param sheetNo sheet 的序号 从1开始
     * @return Excel 数据 list
     */
    public static List<Object> readExcel(MultipartFile excel, BaseRowModel rowModel, int sheetNo) throws ExcelException {
        return readExcel(excel, rowModel, sheetNo, 1);
    }

    /**
     * 读取某个 sheet 的 Excel
     *
     * @param excel 文件
     * @param rowModel 实体类映射，继承 BaseRowModel 类
     * @param sheetNo sheet 的序号 从1开始
     * @param headLineNum 表头行数，默认为1
     * @return Excel 数据 list
     */
    public static List<Object> readExcel(MultipartFile excel, BaseRowModel rowModel, int sheetNo, int headLineNum) throws ExcelException {
        ExcelListener excelListener = new ExcelListener();
        ExcelReader reader = getReader(excel, excelListener);

        if (reader == null) {
            return null;
        }

        reader.read(new Sheet(sheetNo, headLineNum, rowModel.getClass()));

        return excelListener.getDatas();
    }

    /**
     * 导出 Excel ：一个 sheet，带表头
     *
     * @param response HttpServletResponse
     * @param list 数据 list，每个元素为一个 BaseRowModel
     * @param fileName 导出的文件名
     * @param sheetName 导入文件的 sheet 名
     * @param object 映射实体类，Excel 模型
     */
    public static void writeExcel(HttpServletResponse response, List<? extends BaseRowModel> list, String fileName,
                                  String sheetName, BaseRowModel object) throws ExcelException {
        ExcelWriter writer = new ExcelWriter(getOutputStream(fileName, response), ExcelTypeEnum.XLSX);
        Sheet sheet = new Sheet(1, 0, object.getClass());
        sheet.setSheetName(sheetName);

        TableStyle tableStyle = new TableStyle();
        tableStyle.setTableContentBackGroundColor(IndexedColors.WHITE);
        Font font = new Font();
        font.setFontHeightInPoints((short) 9);
        tableStyle.setTableHeadFont(font);
        tableStyle.setTableContentFont(font);
        sheet.setTableStyle(tableStyle);

        writer.write(list, sheet);
        writer.finish();
    }

    /**
     * 导出 Excel ：多个 sheet，带表头
     *
     * @param response HttpServletResponse
     * @param list 数据 list，每个元素为一个 BaseRowModel
     * @param fileName 导出的文件名
     * @param sheetName 导入文件的 sheet 名
     * @param object 映射实体类，Excel 模型
     */
    public static ExcelWriterFactory writeExcelWithSheets(HttpServletResponse response,
                                                          List<? extends BaseRowModel> list, String fileName,
                                                          String sheetName, BaseRowModel object) throws ExcelException {
        ExcelWriterFactory writer = new ExcelWriterFactory(getOutputStream(fileName, response), ExcelTypeEnum.XLSX);
        Sheet sheet = new Sheet(1, 0, object.getClass());
        sheet.setSheetName(sheetName);
        sheet.setTableStyle(getTableStyle());
        writer.write(list, sheet);

        return writer;
    }

    /**
     * 导出融资还款情况表
     *
     * @param response
     * @param list
     * @param fileName
     * @param sheetName
     * @param object
     */
    public static void writeFinanceRepayment(HttpServletResponse response, List<? extends BaseRowModel> list,
                                             String fileName, String sheetName, BaseRowModel object) throws ExcelException {
        ExcelWriter writer = new ExcelWriter(getOutputStream(fileName, response), ExcelTypeEnum.XLSX);
        Sheet sheet = new Sheet(1, 0, object.getClass());
        sheet.setSheetName(sheetName);
        sheet.setTableStyle(getTableStyle());
        writer.write(list, sheet);

        for (int i = 1; i <= list.size(); i += 4) {
            writer.merge(i, i + 3, 0, 0);
            writer.merge(i, i + 3, 1, 1);
        }

        writer.finish();
    }

    /**
     * 导出文件时为Writer生成OutputStream
     */
    private static OutputStream getOutputStream(String fileName, HttpServletResponse response) throws ExcelException {
        //创建本地文件
        fileName = fileName + ".xls";

        try {
            fileName = new String(fileName.getBytes(), "ISO-8859-1");
            response.addHeader("Content-Disposition", "filename=" + fileName);

            return response.getOutputStream();
        } catch (Exception e) {

            throw new ExcelException("导出异常！");
        }
    }

    /**
     * 返回 ExcelReader
     *
     * @param excel 需要解析的 Excel 文件
     * @param excelListener new ExcelListener()
     */
    private static ExcelReader getReader(MultipartFile excel, ExcelListener excelListener) throws ExcelException {
        String filename = excel.getOriginalFilename();

        if (filename == null || (!filename.toLowerCase().endsWith(".xls") && !filename.toLowerCase().endsWith(".xlsx"))) {
            throw new ExcelException("文件格式错误！");
        }
        InputStream inputStream;

        try {
            inputStream = new BufferedInputStream(excel.getInputStream());

            return new ExcelReader(inputStream, null, excelListener, false);
        } catch (IOException e) {
            e.printStackTrace();
        }

        return null;
    }

    /**
     * 资金收支导出 Excel ：一个 sheet，带表头
     *
     * @param response HttpServletResponse
     * @param list 数据 list，每个元素为一个 BaseRowModel
     * @param fileName 导出的文件名
     * @param sheetName 导入文件的 sheet 名
     * @param object 映射实体类，Excel 模型
     */
    public static void exportFundBudgetExcel(HttpServletResponse response, List<? extends BaseRowModel> list,
                                             String fileName, String sheetName, BaseRowModel object) throws IOException, ExcelException {
        ExcelWriter writer = new ExcelWriter(getOutputStream(fileName, response), ExcelTypeEnum.XLSX);
        Sheet sheet = new Sheet(1, 0, object.getClass());
        sheet.setSheetName(sheetName);
        sheet.setTableStyle(getTableStyle());

        writer.write(list, sheet);
        writer.merge(2, 3, 0, 0);
        writer.merge(4, 13, 0, 0);
        writer.merge(14, 14, 0, 1);
        writer.finish();
    }

    /**
     * 读取Excel表格数据，封装成实体
     *
     * @param inputStream
     * @param clazz
     * @param sheetNo
     * @param headLineMun
     * @return
     */
    public static Object readExcel(InputStream inputStream, Class<? extends BaseRowModel> clazz, Integer sheetNo,
                                   Integer headLineMun) {
        if (null == inputStream) {

            throw new NullPointerException("the inputStream is null!");
        }

        ExcelListener listener = new ExcelListener();
        ExcelReader reader = new ExcelReader(inputStream, valueOf(inputStream), null, listener);
        reader.read(new Sheet(sheetNo, headLineMun, clazz));

        return listener.getDatas();
    }

    /**
     * 根据输入流，判断为xls还是xlsx，该方法原本存在于easyexcel 1.1.0 的ExcelTypeEnum中。
     */
    public static ExcelTypeEnum valueOf(InputStream inputStream) {
        try {
            FileMagic fileMagic = FileMagic.valueOf(inputStream);

            if (FileMagic.OLE2.equals(fileMagic)) {
                return ExcelTypeEnum.XLS;
            }

            if (FileMagic.OOXML.equals(fileMagic)) {
                return ExcelTypeEnum.XLSX;
            }

            throw new ExcelException("excelTypeEnum can not null");

        } catch (IOException | ExcelException e) {
            throw new RuntimeException(e);
        }
    }

    /**
     * 设置全局样式
     *
     * @return
     */
    private static TableStyle getTableStyle() {
        TableStyle tableStyle = new TableStyle();

        tableStyle.setTableContentBackGroundColor(IndexedColors.WHITE);
        Font font = new Font();
        font.setBold(true);
        font.setFontHeightInPoints((short) 9);
        tableStyle.setTableHeadFont(font);
        Font fontContent = new Font();
        fontContent.setFontHeightInPoints((short) 9);
        tableStyle.setTableContentFont(fontContent);

        return tableStyle;
    }
}

5：controller控制器

file为前端传递过来的的excel文件，DataGridView为json数据的返回值工具类。具体用于LayUI

注意事项：如果需要对都进来的数据进行保存操作的时候，如果使用的是mybatisplus的语法会报错，提示没有cellStyleMap这个属性。

       解决方法：
          1：`private Map<Integer, CellStyle> cellStyleMap = new HashMap<Integer,CellStyle>();`在实体类上加上这个属性。不过我没                
              有成功。
          2：自己在持久层上写上自己的方法，不用mybatisplus的方法即可。

public DataGridView read(MultipartFile file) throws ExcelException {
        Object objList = ExcelUtil.readExcel(file, new Task(), 1, 1);
        if (objList == null) {
            return new DataGridView(-1, "读取失败");
        }
        List orderList = (List) objList;
        if (orderList == null || orderList.size() <= 0) {
            return new DataGridView(-1, "读取失败");
        }
        orderList.forEach(System.out::println);
        for (Object o : orderList) {
            Task task = (Task) o;
            //System.out.println(task.getId());
            //System.out.println(task.getMonovalent());
            //System.out.println(task.getName());        
            taskService.addTask(task);
        }
        return new DataGridView(0, "读取成功");
    }

原文链接：原文链接

官方文档：官方文档