是一个处理微软各种文件格式的开源项目，一般情况下，POI都是用来操作EXCEL文件的 读和写操作
test测试
/*

• 使用POI操作Excel文件

• */
  public class POITest {

  /*

  • 通过POI创建Excel文件并写入文件内容

  • */
    public static void write() throws Exception{
    //在内存中创建一个excel文件
    XSSFWorkbook excel=new XSSFWorkbook();
    //在Excel文件中创建一个sheet页
    XSSFSheet sheet = excel.createSheet(“info”);
    //在sheet中创建行对象，rownum编号从0开始
    XSSFRow row = sheet.createRow(1);
    //创建单元格并写入文件内容
    row.createCell(1).setCellValue(“姓名”);
    row.createCell(2).setCellValue(“城市”);

    //创建一个新行
    row = sheet.createRow(2);
    row.createCell(1).setCellValue(“张三”);
    row.createCell(2).setCellValue(“北京”);

    row = sheet.createRow(3);
    row.createCell(1).setCellValue(“李四”);
    row.createCell(2).setCellValue(“南京”);

    //通过输出流将内存中的Excel文件写入磁盘中
    FileOutputStream out=new FileOutputStream(new File(“/Users/renliaoliao/Desktop/info.xlsx”));
    excel.write(out);

    //关闭资源
    out.close();
    excel.close();
    }

  /*

  • 通过POI读取Excel文件中的内容

  • */
    public static void read() throws Exception{
    //读取磁盘上以及存在的excel文件
    FileInputStream in = new FileInputStream(new File(“/Users/renliaoliao/Desktop/info.xlsx”));
    XSSFWorkbook excel = new XSSFWorkbook(in);
    //将文本文件读取出来 读取第一个sheet页
    XSSFSheet sheet = excel.getSheetAt(0);

    //获取sheet页中最后一行的行号
    int lastRowNum = sheet.getLastRowNum();

    for (int i=1;i<=lastRowNum;i++){
    //获取某一行
    XSSFRow row = sheet.getRow(i);
    //获取单元格对象
    String cellValue1 = row.getCell(1).getStringCellValue();
    String cellValue2 = row.getCell(2).getStringCellValue();
    System.out.println(cellValue1+" "+cellValue2);
    }

    //关闭资源
    in.close();
    excel.close();
    }
    public static void main(String[] args) throws Exception {
    //write();
    read();
    }
    }

导出运营数据表数据
/*
* 导出运营数据报表
* */
@Override
public void expo rtBusinessData(HttpServletResponse response) {
//1.查询数据库 获取运营数据
LocalDate dateBegin = LocalDate.now().minusDays(30);
LocalDate dateEnd = LocalDate.now().minusDays(1);
//查询概览数据
BusinessDataVO businessDataVO = workspaceService.getBusinessData(LocalDateTime.of(dateBegin, LocalTime.MIN), LocalDateTime.of(dateEnd, LocalTime.MAX));

    //2.通过POI将数据写入到Excel文件中InputStream in = this.getClass().getClassLoader().getResourceAsStream("template/运营数据报表模板.xlsx");try {//基于模板文件创建一个新的excel文件XSSFWorkbook excel = new XSSFWorkbook(in);//获取表格标签的sheet页XSSFSheet sheet = excel.getSheet("Sheet1");//填充数据--时间sheet.getRow(1).getCell(1).setCellValue("时间："+dateBegin+"至"+dateEnd);//获取第四行XSSFRow row = sheet.getRow(3);row.getCell(2).setCellValue(businessDataVO.getTurnover());row.getCell(4).setCellValue(businessDataVO.getOrderCompletionRate());row.getCell(6).setCellValue(businessDataVO.getNewUsers());//获得第五行row = sheet.getRow(4);row.getCell(2).setCellValue(businessDataVO.getValidOrderCount());row.getCell(4).setCellValue(businessDataVO.getUnitPrice());//填充明细数据for (int i = 0; i < 30; i++) {LocalDate date = dateBegin.plusDays(i);//查询某一天的营业数据BusinessDataVO businessData = workspaceService.getBusinessData(LocalDateTime.of(date, LocalTime.MIN), LocalDateTime.of(date, LocalTime.MAX));//获得某一行row=sheet.getRow(7+i);row.getCell(1).setCellValue(date.toString());row.getCell(2).setCellValue(businessData.getTurnover());row.getCell(3).setCellValue(businessData.getValidOrderCount());row.getCell(4).setCellValue(businessData.getOrderCompletionRate());row.getCell(5).setCellValue(businessData.getUnitPrice());row.getCell(6).setCellValue(businessData.getNewUsers());}//3.通过输出流将excel文件下载到客户端浏览器ServletOutputStream out = response.getOutputStream();excel.write(out);//关闭资源out.close();excel.close();} catch (IOException e) {throw new RuntimeException(e);}}

}