本文参考：https://liuyanzhao.com/10060.html
先说两个实体类对象。
我这里举例 Student 和 StudentExcel
Student 就是你数据库表的对象
StudentExcel 是你导入进来的Excel对应的字段 ，为啥写他，用来校验数据格式，判空处理
你要把你导入进来的对象 StudentExcel 转换成 你业务对象 Student ，转换方式我下面有工具类，大家可以参考去改一下。

如果你导入的参数有校验，或者不能为null，可以加注解来校验，日期校验注解是我自己写的注解，我一会下面会放大家直接copy就可以用。

目录

• 1.模板copy到项目里
• 2.下载模板
• 3.导入
• 4.导出
• 5.工具类 FileUtil ：
• 6.工具类 ValidatorUtils （导入的时候参数校验）
• 7.校验日期注解

1.模板copy到项目里

这个模板是你自己定义的写好的直接扔到项目里就行，不要直接扔在resources目录下，创一个文件夹（template）放进去。 看图：

pom.xml添加依赖

<dependency><groupId>com.alibaba</groupId><artifactId>easyexcel</artifactId><version>3.0.5</version>
</dependency>

**StudentExcel Excel对象

import lombok.AllArgsConstructor;
import lombok.Builder;
import lombok.Data;
import lombok.NoArgsConstructor;import javax.validation.constraints.NotBlank;
import javax.validation.constraints.Pattern;
import java.io.Serializable;/*** @author ext.libo15* @title: 导入员工花名册* @date 2022/3/2 13:49*/
@Data
@Builder
@NoArgsConstructor
@AllArgsConstructor
@HeadRowHeight(value = 40)
public class StudentExcel implements Serializable {private static final long serialVersionUID = -5144055068797033748L;/*** 姓名*/@ExcelProperty(value = "姓名", index = 0)@ColumnWidth(value = 20)@NotBlank(message="姓名不能为空")private String name;/*** 性别 1：男 ：2女*/@ExcelProperty(value = "性别\r1：男 ：2女", index = 1)@ColumnWidth(value = 20)@NotBlank(message="性别不能为空")private String gender;/*** 出生日期*/@ExcelProperty(value = "出生日期", index = 2)@ColumnWidth(value = 20)@NotBlank(message="出生日期不能为空")@DateTimeStr(format ="yyyy-MM-dd", message = "出生日期格式错误，正确格式为：yyyy-MM-dd")private String birthday;/*** 年龄*/@ExcelProperty(value = "年龄", index = 3)@ColumnWidth(value = 20)@NotBlank(message="年龄不能为空")private String age;/*** 身份证号码*/@ExcelProperty(value = "身份证号码", index = 4)@ColumnWidth(value = 20)@NotBlank(message="身份证号码不能为空")@Pattern(regexp = "^\\d{15}$|^\\d{17}[0-9Xx]$",message = "身份证格式不正确!")//长度18，0-9private String cardNo;/*** 联系电话*/@ExcelProperty(value = "联系电话", index = 5)@ColumnWidth(value = 20)@NotBlank(message="联系电话不能为空")@Pattern(regexp = "^[1][3,4,5,7,8][0-9]{9}$",message = "联系电话格式不正确!")//长度11private String telephone;/*** 是否已婚 1：是  2：否*/@ExcelProperty(value = "是否已婚", index = 6)@ColumnWidth(value = 20)@NotBlank(message="是否已婚不能为空")private String marryStatus;/*** 银行卡号*/@ExcelProperty(value = "银行卡号", index = 8)@ColumnWidth(value = 20)@NotBlank(message="银行卡号不能为空")@Pattern(regexp = "^([1-9]{1})(\\d{14}|\\d{18})$",message = "银行卡号格式不正确!")//长度11private String bankCardNo;

Student 对象（你的业务对象，就是数据库对应的对象）

public class Student implements Serializable {private static final long serialVersionUID = -5144055068797033748L;/*** 姓名*/private String name;/*** 性别 1：男 ：2女*/private int gender;/*** 出生日期*/private Date birthday;/*** 年龄*/private int age;/*** 身份证号码*/private String cardNo;/*** 联系电话*/private String telephone;/*** 是否已婚 1：是  2：否*/private int marryStatus;/*** 银行卡号*/private String bankCardNo;/*** 时间*/private Date dimissionDate;

Controller 代码：

    /*** 导入*/@RequestMapping(value="/import")public void importExcel(HttpServletRequest request, HttpServletResponse response,@RequestBody MultipartFile file) throws Exception {staffManageService.importExcel(file);}/*** 导出*/@RequestMapping(value="/export",method = RequestMethod.POST)public void batchExport(HttpServletResponse response) throws ParseException {staffManageService.export(response,staffRosterVo);}/*** 下载模板** @param* @return* @throws Exception* @author ext.libo15* @date 2022/2/28 17:23*/@GetMapping(value="/download")public void download(HttpServletRequest request, HttpServletResponse response) throws FileNotFoundException {FileUtil.downloadExcel(request,response);}
}

2.下载模板

这里其实 Controller + FileUtil 工具类，下载模板的操作已经做好了。工具类我放最下面了

**

3.导入

**

    /*** 导入* @param file*/@Overridepublic void importExcel(MultipartFile file) throws Exception {List<Student> ExcelList = null;String validate = "";//校验文件大小 100Mboolean size = FileUtil.checkFileSize(file.getSize(), 100, ResponseResultEnum.FILE_UNIT.getMsg());if(size == false){//文件过大啦，只能100M}//excel读取数据staffExcelList = EasyExcel.read(new BufferedInputStream(file.getInputStream())).head(StaffDataExcel.class).sheet().doReadSync();if (ExcelList.size() > 1000) {//最多导入1000条哦}// excel数据校验validate = ValidatorUtils.beanValidate(ExcelList);if(!validate.equals("success")){//参数异常提示  如：姓名不能为空哦~}//把Excel数据转换成你对应的对象集合ListList<Student> studentList = ExcelUtil.excelListConvertList(ExcelList);//拿到数据后就可以 入库操作啦 -----我自己的入库就不给你们写了StudentService.importExcel(studentList );}

4.导出

    /*** 导出* @param response* @param staffRosterVo* @return* @throws ParseException*/@Overridepublic void export(HttpServletResponse response) throws ParseException {String fileName = "导出的文件名称";String sheetName = "导出的 sheetName ";List<Student> list = studentService.findList();List<StaffDataExportExcel> studentExcelList = ExcelUtil.listConvertexcelList(list );try {ExcelUtil.writeExcel(response, studentExcelList , fileName, sheetName, StaffDataExportExcel.class);} catch (Exception e) {e.printStackTrace();}}

5.工具类 FileUtil ：

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.FileInputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URLEncoder;public class FileUtil {/*** 判断文件大小** @param len*            文件长度* @param size*            限制大小* @param unit*            限制单位（B,K,M,G）* @return*/public static boolean checkFileSize(Long len, int size, String unit) {
//        long len = file.length();double fileSize = 0;if ("B".equals(unit.toUpperCase())) {fileSize = (double) len;} else if ("K".equals(unit.toUpperCase())) {fileSize = (double) len / 1024;} else if ("M".equals(unit.toUpperCase())) {fileSize = (double) len / 1048576;} else if ("G".equals(unit.toUpperCase())) {fileSize = (double) len / 1073741824;}if (fileSize > size) {return false;}return true;}public static void downLoadFile(String filePath, String fileName, HttpServletResponse response) {try (InputStream inStream = new FileInputStream(filePath);OutputStream os = response.getOutputStream()) {response.setHeader("Content-Disposition", "attachment; fileName=" + URLEncoder.encode(fileName, "UTF-8"));response.setContentType("application/vnd.openxmlformats-officedocument.spreadsheetml.sheet");response.setCharacterEncoding("utf-8");byte[] buff = new byte[100];int len;while ((len = inStream.read(buff)) > 0) {os.write(buff, 0, len);}os.flush();} catch (Exception e) {throw new BusinessException(ResponseResultEnum.FILE_IMPMOT_SIZE.getCode(), ResponseResultEnum.FILE_IMPMOT_SIZE.getMsg());}}//下载模板public static void downloadExcel(HttpServletRequest request, HttpServletResponse response){//方法一：直接下载路径下的文件模板（这种方式貌似在SpringCloud和Springboot中，打包成JAR包时，无法读取到指定路径下面的文件，不知道记错没，你们可以自己尝试下！！！）try {//文件名称String fileName = "importStaffRoster.xlsx";//设置要下载的文件的名称response.setHeader("Content-disposition", "attachment;fileName=" + fileName);//通知客服文件的MIME类型response.setContentType("application/vnd.ms-excel;charset=UTF-8");//获取文件的路径String filePath = FileUtil.class.getResource("/template/" + fileName).getPath();FileInputStream input = new FileInputStream(filePath);OutputStream out = response.getOutputStream();byte[] b = new byte[2048];int len;while ((len = input.read(b)) != -1) {out.write(b, 0, len);}//修正 Excel在“xxx.xlsx”中发现不可读取的内容。是否恢复此工作薄的内容？如果信任此工作簿的来源，请点击"是"response.setHeader("Content-Length", String.valueOf(input.getChannel().size()));input.close();} catch (Exception ex) {ex.printStackTrace();}}}

6.工具类 ValidatorUtils （导入的时候参数校验）

import cn.hutool.core.lang.Assert;
import org.apache.commons.lang3.ObjectUtils;import javax.validation.ConstraintViolation;
import javax.validation.Valid;
import javax.validation.Validation;
import javax.validation.Validator;
import java.util.*;public class ValidatorUtils {private static final Validator validator = Validation.buildDefaultValidatorFactory().getValidator();public static String beanValidate(@Valid Object obj) throws IllegalArgumentException {if (obj instanceof Collection) {ValidCollection<Object> validCollection = new ValidCollection<>();validCollection.setList((Collection) obj);return validate(validCollection);} else {return validate(obj);}}public static String validate(@Valid Object obj) {try {Map<String, String> validatedMsg = new HashMap<>();Set<ConstraintViolation<Object>> constraintViolations = validator.validate(obj);String validate = "";String message = "";for (ConstraintViolation<Object> c : constraintViolations) {validate = c.getPropertyPath().toString();validate = validate.substring(5,6);int unm = Integer.valueOf(validate) +1;validatedMsg.put( "表格第"+unm+"条 ", c.getMessage());}Assert.isTrue(ObjectUtils.isEmpty(constraintViolations), validatedMsg.toString());} catch (IllegalArgumentException e) {e.printStackTrace();return e.getMessage();}return "success";}private static class ValidCollection<T> {@Validprivate Collection<T> list;public Collection<T> getList() {return list;}public void setList(Collection<T> list) {this.list = list;}}
}

工具类

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.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.List;public class ExcelUtil {/*** 导出* @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 {//表头样式WriteCellStyle headWriteCellStyle = new WriteCellStyle();//设置表头居中对齐headWriteCellStyle.setHorizontalAlignment(HorizontalAlignment.CENTER);//内容样式WriteCellStyle contentWriteCellStyle = new WriteCellStyle();//设置内容靠左对齐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");return response.getOutputStream();}/** Excel转换实体类对象*/public static List<Student> excelListConvertList(List<StudentExcel> studentExcelList) throws ParseException {SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");List<Student> list = new ArrayList<>();for (StudentExcel s : studentExcelList) {Student student = Student.builder().name(staffDataExcel.getname()).age(staffDataExcel.age()).city(staffDataExcel.getCity()).sex(staffDataExcel.getsex().equals("男")?1:2).birthday(sdf.parse(staffDataExcel.getBirthday())).build();list.add(student);}return list ;}/**  导出的List集合 转换 Excel*/public static List<StudentExportExcel> listConvertexcelList(List<Student> student) throws ParseException {SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");List<StudentExcel> list= new ArrayList<>();for (Student s : student) {StudentExcel excel = StudentExcel.builder().name(staffDataExcel.getname()).age(staffDataExcel.age()).city(staffDataExcel.getCity()).sex(staffDataExcel.getsex().equals("男")?1:2).birthday(sdf.parse(staffDataExcel.getBirthday())).build();.build();list.add(excel);}return list;}}

7.校验日期注解

import javax.validation.Constraint;
import javax.validation.Payload;
import java.lang.annotation.*;@Target({ElementType.FIELD, ElementType.PARAMETER})
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Constraint(validatedBy = CheckDateTimeCaseValidator.class)
public @interface DateTimeStr {String message() default "{javax.validation.constraints.DateTimeStr.message}";String format() default "yyyy-MM-dd";Class<?>[] groups() default {};Class<? extends Payload>[] payload() default {};
}