Apache POI是Apache软件基金会的开放源码函式库，POI提供API给Java程序对Microsoft Office格式档案读和写的功能。
一、Excel2003版与Excel2007版对比
1.Excel2003版扩展名.xls；Excel2007版扩展名.xlsx。
2.Excel2003版只能打开.xls后缀的文件；Excel2007版能打开.xlsx和.xls。
3.Excel2003版是二进制格式，存储量少；Excel2007版基于xml压缩的，存储量大，占用空间少，操作效率高。
本次只做Springboot对Excel2007版操作；不执行对数据库操作
二、步骤
1.创建一个新的Springboot项目，我使用前期创建好的hello-rabbit，导入核心依赖
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.2.2.RELEASE</version>
<relativePath/>
</parent>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<optional>true</optional>
</dependency>
<!--spring boot web的依赖-->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<!--Apache Poi 依赖-->
<dependency>
<groupId>org.apache.poi</groupId>
<artifactId>poi</artifactId>
<version>4.0.1</version>
</dependency>
<dependency>
<groupId>org.apache.poi</groupId>
<artifactId>poi-ooxml-schemas</artifactId>
<version>4.0.1</version>
</dependency>
<dependency>
<groupId>org.apache.poi</groupId>
<artifactId>poi-ooxml</artifactId>
<version>4.0.1</version>
</dependency>
2.创建一个实体类Teacher.java，与Excel数据对称
package com.basic.hellorabbit.entity;
import lombok.Data;
/**
* @Description: 老师类
* @Author: Joe
* @CreateDate: 2020/3/20 15:09
*/
@Data
public class Teacher {
private Integer id;
private String name;
private Integer age;
private String sex;
private String subject;
public Teacher() {
}
public Teacher(Integer id, String name, Integer age, String sex, String subject) {
this.id = id;
this.name = name;
this.age = age;
this.sex = sex;
this.subject = subject;
}
}
3.创建一个封装类ExcelDatas.java，用于给工具类整理数据
package com.basic.hellorabbit.entity;
import lombok.Data;
import java.util.List;
/**
* @Description: 数据操作类
* @Author: Joe
* @CreateDate: 2020/3/20 11:12
*/
@Data
public class ExcelDatas {
/**
* 文件名
*/
private String fileName;
/**
* 数据的表头(类属性)
*/
private String[] head;
/**
* 数据集合
*/
private List<Teacher> datas;
}
4.创建一个工具类（创建读取Excel标题，表头，行列数据）ExcelUtil.java，整合数据操作
这个不是很全面，大家可以去封装更丰富的样式
package com.basic.hellorabbit.util;
import com.basic.hellorabbit.entity.ExcelDatas;
import com.basic.hellorabbit.entity.Teacher;
import lombok.extern.slf4j.Slf4j;
import org.apache.poi.hssf.usermodel.HSSFDataFormat;
import org.apache.poi.ss.usermodel.*;
import org.apache.poi.xssf.usermodel.*;
import javax.servlet.http.HttpServletResponse;
import java.io.BufferedOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.lang.reflect.Field;
import java.util.ArrayList;
import java.util.List;
import static org.apache.poi.ss.usermodel.CellType.*;
/**
* @Description: Excel工具类
* @Author: Joe
* @CreateDate: 2020/3/19 20:40
*/
@Slf4j
public class ExcelUtil {
public static void exportExcel(HttpServletResponse response, ExcelDatas data) {
log.info("导出解析开始，fileName:{}",data.getFileName());
try {
//实例化HSSFWorkbook
XSSFWorkbook workbook = new XSSFWorkbook();
//创建一个Excel表单，参数为sheet的名字
XSSFSheet sheet = workbook.createSheet("sheet");
//设置表头
setTitle(workbook, sheet, data.getHead());
//设置单元格并赋值
setData(sheet, data.getDatas());
//设置浏览器下载
setBrowser(response, workbook, data.getFileName());
log.info("导出解析成功!");
} catch (Exception e) {
log.info("导出解析失败!");
e.printStackTrace();
}
}
/**
* 设置标题
* @param workbook
* @param sheet
* @param str
*/
private static void setTitle(XSSFWorkbook workbook, XSSFSheet sheet, String[] str) {
try {
XSSFRow row = sheet.createRow(0);
//设置为居中加粗,格式化时间格式
XSSFCellStyle style = workbook.createCellStyle();
XSSFFont font = workbook.createFont();
font.setBold(true);
style.setFont(font);
style.setDataFormat(HSSFDataFormat.getBuiltinFormat("m/d/yy h:mm"));
//创建表头名称
XSSFCell cell;
for (int j = 0; j < str.length; j++) {
cell = row.createCell(j);
cell.setCellValue(str[j]);
cell.setCellStyle(style);
}
} catch (Exception e) {
log.info("导出时设置表头失败！");
e.printStackTrace();
}
}
/**
* 添加数据
* @param sheet
* @param data
*/
private static void setData(XSSFSheet sheet, List<Teacher> data) {
Teacher teacher=new Teacher();
Field[] fields = teacher.getClass().getDeclaredFields();
try{
int rowNum = 1;
for (int i = 0; i < data.size(); i++) {
XSSFRow row = sheet.createRow(rowNum);
teacher = data.get(i);
for (int j = 0; j < fields.length; j++) {
if (j==0){
row.createCell(j).setCellValue(teacher.getId());
}
if (j==1){
row.createCell(j).setCellValue(teacher.getName());
}
if (j==2){
row.createCell(j).setCellValue(teacher.getAge());
}
if (j==3){
row.createCell(j).setCellValue(teacher.getSex());
}
if (j==4){
row.createCell(j).setCellValue(teacher.getSubject());
}
}
rowNum++;
}
log.info("表格赋值成功！");
}catch (Exception e){
log.info("表格赋值失败！");
e.printStackTrace();
}
}
/**
* 使用浏览器下载
* @param response
* @param workbook
* @param fileName
*/
private static void setBrowser(HttpServletResponse response, XSSFWorkbook workbook, String fileName) {
try {
//清空response
response.reset();
//设置response的Header
response.addHeader("Content-Disposition", "attachment;filename=" + fileName);
OutputStream os = new BufferedOutputStream(response.getOutputStream());
response.setContentType("application/vnd.ms-excel;charset=gb2312");
//将excel写入到输出流中
workbook.write(os);
os.flush();
os.close();
log.info("设置浏览器下载成功！");
} catch (Exception e) {
log.info("设置浏览器下载失败！");
e.printStackTrace();
}
}
/**
* 导入解析
* @param
* @return
*/
public static List<Object[]> importExcel(InputStream inputStream, String fileName) {
log.info("导入解析开始，fileName:{}",fileName);
try {
List<Object[]> list = new ArrayList<>();
//InputStream inputStream = new FileInputStream(fileName);
Workbook workbook = WorkbookFactory.create(inputStream);
Sheet sheet = workbook.getSheetAt(0);
//获取sheet的行数
int rows = sheet.getPhysicalNumberOfRows();
for (int i = 0; i < rows; i++) {
//过滤表头行
if (i == 0) {
continue;
}
//获取当前行的数据
Row row = sheet.getRow(i);
Object[] objects = new Object[row.getPhysicalNumberOfCells()];
int index = 0;
for (Cell cell : row) {
if (cell.getCellType().equals(NUMERIC)) {
objects[index] = (int) cell.getNumericCellValue();
}
if (cell.getCellType().equals(STRING)) {
objects[index] = cell.getStringCellValue();
}
if (cell.getCellType().equals(BOOLEAN)) {
objects[index] = cell.getBooleanCellValue();
}
if (cell.getCellType().equals(ERROR)) {
objects[index] = cell.getErrorCellValue();
}
if (cell.getCellType().equals(BLANK)) {
objects[index] = " ";
}
if (cell.getCellType().equals(FORMULA)) {
objects[index] = cell.getCellFormula();
}
index++;
}
list.add(objects);
}
log.info("导入文件解析成功！");
return list;
}catch (Exception e){
log.info("导入文件解析失败！");
e.printStackTrace();
}
return null;
}
}
5.在/resources/templates下新建excel.html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Excel测试页面</title>
</head>
<body>
<h3>数据导入</h3>
<br>
<hr/>
<form method="post" enctype="multipart/form-data" action="/importExcel">
<p>
导入文件<input type="file" name="file"/>
</p>
<p>
<input type="submit" value="开始导入"/>
</p>
</form>
<br>
<h3>Excel导出表格测试页面</h3>
<br>
<a href="/export">导出表格</a>
<hr/>
</body>
</html>
6.创建一个Controller类ExcelController.java，进行数据导入、导出
package com.basic.hellorabbit.controller;
import com.basic.hellorabbit.entity.ExcelDatas;
import com.basic.hellorabbit.entity.Teacher;
import com.basic.hellorabbit.util.ExcelUtil;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.multipart.MultipartFile;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.List;
/**
* @Description: Excel测试页面
* @Author: Joe
* @CreateDate: 2020/3/20 17:15
*/
@Controller
public class ExcelController {
/**
* 跳转到Excel测试页面
* @return
*/
@RequestMapping(value = "/toexcel",method = RequestMethod.GET)
public String toExcel(){
return "excel";
}
/**
* 数据导出
* @param response
*/
@RequestMapping(value = "/export",method = RequestMethod.GET)
public void ExportExcel(HttpServletResponse response){
List<Teacher> teachers = new ArrayList<>();
teachers.add(new Teacher(1,"韩信",25,"男","刺客"));
teachers.add(new Teacher(1,"钟无艳",25,"女","战士"));
ExcelDatas excelDatas = new ExcelDatas();
excelDatas.setFileName("teachers.xlsx");
String[] strings = {"id","姓名","年纪","性别","科目"};
excelDatas.setHead(strings);
excelDatas.setDatas(teachers);
ExcelUtil.exportExcel(response,excelDatas);
}
/**
* 数据导入
* @param file
*/
@ResponseBody
@RequestMapping(value = "/importExcel",method = RequestMethod.POST)
public String importExcel(MultipartFile file) throws IOException {
InputStream inputStream = file.getInputStream();
String fileName = file.getName();
List<Object[]> list = ExcelUtil.importExcel(inputStream,fileName);
for (int i = 0; i < list.size(); i++) {
Teacher teacher = new Teacher();
teacher.setId((Integer)list.get(i)[0]);
teacher.setName((String) list.get(i)[1]);
teacher.setAge((Integer)list.get(i)[2]);
teacher.setSex((String)list.get(i)[3]);
teacher.setSubject((String) list.get(i)[4]);
System.out.println(teacher.toString());
}
return "导入成功！";
}
}
7.如图Excel表格
