java使用poi-ooxml操作excel

读取excel

InputStream stream = new FileInputStream(file);
Workbook wb = new HSSFWorkbook(stream);
int sheetSize = wb.getNumberOfSheets();
List<List<List>> sheetList = new ArrayList<>();
for (int i = 0; i < sheetSize; i++) {
    List<List> outerList = new ArrayList<>();
    Sheet sheet = wb.getSheetAt(i);
    for (int j = 0; j <= sheet.getLastRowNum(); j++) {
        List<String> list = new ArrayList<>();
        for (int c = 0; c < sheet.getRow(j).getLastCellNum(); c++) {
            Cell cell = sheet.getRow(j).getCell(c);
            String str = cell.getStringCellValue();
            list.add(str);
        }
        outerList.add(list);
    }
    sheetList.add(outerList);
}

写入excel

HSSFWorkbook hssfWorkbook = new HSSFWorkbook();
HSSFSheet sheet = hssfWorkbook.getSheetAt(0);
for (int k = 0 ; k < 数组.size(); k++) {
    HSSFRow hssfRow = sheet.createRow(k);
    hssfRow.createCell(0).setCellValue("..............");
}
File jsonFile = new File("。。。。。。。。。。。");
FileOutputStream out = new FileOutputStream(jsonFile);

hssfWorkbook.write(out);

注意事项：

Excel2003版本：后缀是.xls，对应poi的HSSF系，HSSFWorkbook、HSSFSheet……

Excel2007版本：后缀是.xlsx，对应poi的XSSF系，XSSFWorkbook、XSSFSheet……