pom.xml 添加Apache POL依赖

<dependency>
<groupId>org.apache.poi</groupId>
<artifactId>poi</artifactId>
<version>3.14</version>
</dependency>

导出excel

导出excel比较重要的api有以下几个，其他的并无难点

创建一个excel文件工作薄；（HSSFWorkbook workbook = new HSSFWorkbook()）
创建一张表；HSSFSheet sheet = workbook.createSheet("统计表")
创建一行；HSSFRow row = sheet.createRow(0)
填充一列数据; row.createCell(0).setCellValue("数据")
设置一个单元格样式；cell.setCellStyle(style)
package com.spring.jianyue.api.controller;

import com.spring.jianyue.api.entity.User;
import com.spring.jianyue.api.entity.vo.ArticleVO;
import com.spring.jianyue.api.service.ArticleService;
import com.spring.jianyue.api.service.UserService;
import org.apache.poi.hssf.usermodel.*;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import javax.servlet.http.HttpServletResponse;
import java.io.FileOutputStream;
import java.io.OutputStream;
import java.net.URLEncoder;
import java.util.List;
@RestController
@RequestMapping(value = "/api/excel")
public class ExcelController {
@Autowired
private ArticleService articleService;

//创建表头
private void createTitle(HSSFWorkbook workbook, HSSFSheet sheet){
HSSFRow row = sheet.createRow(0);
//设置列宽，setColumnWidth的第二个参数要乘以256，这个参数的单位是1/256个字符宽度
sheet.setColumnWidth(1,12256);
sheet.setColumnWidth(3,17256);

//设置为居中加粗
HSSFCellStyle style = workbook.createCellStyle();
HSSFFont font = workbook.createFont();
font.setBold(true);
style.setAlignment(HSSFCellStyle.ALIGN_CENTER);
style.setFont(font);

HSSFCell cell;
cell = row.createCell(0);
cell.setCellValue("ID");
cell.setCellStyle(style);


cell = row.createCell(1);
cell.setCellValue("显示名");
cell.setCellStyle(style);

cell = row.createCell(2);
cell.setCellValue("用户名");
cell.setCellStyle(style);

cell = row.createCell(3);
cell.setCellValue("创建时间");
cell.setCellStyle(style);

}

//生成Article表excel
@GetMapping(value = "/getart")
public String getArticle(HttpServletResponse response) throws Exception{
HSSFWorkbook workbook = new HSSFWorkbook();
HSSFSheet sheet = workbook.createSheet("统计表");
createTitle(workbook,sheet);
List<ArticleVO> rows = articleService.selectAll();

//设置日期格式
HSSFCellStyle style = workbook.createCellStyle();
style.setDataFormat(HSSFDataFormat.getBuiltinFormat("m/d/yy h:mm"));

//新增数据行，并且设置单元格数据
int rowNum=1;
for(ArticleVO articleVO:rows){
    HSSFRow row = sheet.createRow(rowNum);
    row.createCell(0).setCellValue(articleVO.getId());
    row.createCell(1).setCellValue(articleVO.getuId());
    row.createCell(2).setCellValue(articleVO.getTitle());
    row.createCell(3).setCellValue(articleVO.getContent());
    row.createCell(4).setCellValue(articleVO.getNickname());
  //  row.createCell(5).setCellValue(articleVO.getAvatar());
    HSSFCell cell = row.createCell(3);
    cell.setCellValue(articleVO.getCreateTime());
    cell.setCellStyle(style);
    rowNum++;
}

String fileName = "导出excel例子.xls";

//生成excel文件
buildExcelFile(fileName, workbook);

//浏览器下载excel
buildExcelDocument(fileName,workbook,response);

return "download excel";

}

//生成excel文件
protected void buildExcelFile(String filename,HSSFWorkbook workbook) throws Exception{
FileOutputStream fos = new FileOutputStream(filename);
workbook.write(fos);
fos.flush();
fos.close();
}

//浏览器下载excel
protected void buildExcelDocument(String filename,HSSFWorkbook workbook,HttpServletResponse response) throws Exception{
response.setContentType("application/vnd.ms-excel");
response.setHeader("Content-Disposition", "attachment;filename="+ URLEncoder.encode(filename, "utf-8"));
OutputStream outputStream = response.getOutputStream();
workbook.write(outputStream);
outputStream.flush();
outputStream.close();
}