分批导出到本地文件夹

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

-- 工具方法
/**
 *
 * @param fileName 存入文件夹地址
 * @param exportData 导出数据
 * @param dataVo 导出对象
 * @param sheetName sheet名字
 * @return
 * @throws IOException
 */
public static File exportAliOss(String fileName, List<?> exportData, Class<?> dataVo, String sheetName) throws IOException {
    if (exportData.isEmpty()) {
        log.info("导出数据集合为空" + sheetName + "exportData={}", exportData);
        return null;
    }
    //创建导出文件夹
    File file = new File(fileName);
    if (!file.exists()) {
        file.mkdirs();
    }
    FileOutputStream fileOut = null;
    try {
        //将Excel文件写入文件夹下
        long time = System.currentTimeMillis();
        fileOut = new FileOutputStream(fileName + "/" + time + sheetName + ".xlsx");
        ExcelWriter excelWriter = EasyExcel.write(fileOut).build();
        //分割数据，50万存放一个sheet
        List<? extends List<?>> partition = Lists.partition(exportData, 500000);

        //开始分批查询分次写入
        for (int i = 0; i < partition.size(); i++) {
            //创建Sheet
            WriteSheet sheet = new WriteSheet();
            sheet.setSheetName("Sheet" + i);
            sheet.setSheetNo(i);
            List<?> list = partition.get(i);
            WriteSheet writeSheet = EasyExcel.writerSheet(i, sheetName + (i + 1)).head(dataVo)
                    .registerWriteHandler(new LongestMatchColumnWidthStyleStrategy()).build();
            //写数据
            excelWriter.write(list, writeSheet);
        }
        excelWriter.finish();

        File fileUrl = new File(fileName + "/" + time + sheetName + ".xlsx");
        return fileUrl;
    } catch (Exception exception) {
        log.error("导出写入数据异常 msg={}", exception.getMessage());
    } finally {
        fileOut.close();
    }
    return null;
}