最近有個場景，在ftp服務器上，讀取csv文件并入庫，但是客戶提供的一部分文件卻是xls文件，就得搞個將excel轉為csv文件的方法，話不多說直接開干。

方法

    public static void convertExcelToCSV(String excelFilePath, String csvFilePath) throws IOException {FileInputStream inputStream = new FileInputStream(excelFilePath);Workbook workbook = getWorkbook(inputStream, excelFilePath);inputStream.close();FileWriter writer = new FileWriter(csvFilePath);for (int sheetIndex = 0; sheetIndex < workbook.getNumberOfSheets(); sheetIndex++) {Sheet sheet = workbook.getSheetAt(sheetIndex);Iterator<Row> rowIterator = sheet.iterator();while (rowIterator.hasNext()) {Row row = rowIterator.next();Iterator<Cell> cellIterator = row.cellIterator();StringBuilder stringBuilder = new StringBuilder();while (cellIterator.hasNext()) {Cell cell = cellIterator.next();stringBuilder.append(getCellValue(cell));if (cellIterator.hasNext()) {stringBuilder.append(",");}}writer.write(stringBuilder.toString() + "\n");}if (sheetIndex < workbook.getNumberOfSheets() - 1) {writer.write("\n"); // 在不同工作表之間添加一個空行}}writer.flush();writer.close();workbook.close();}private static Workbook getWorkbook(FileInputStream inputStream, String excelFilePath) throws IOException {Workbook workbook = null;if (excelFilePath.endsWith("xlsx")) {workbook = new XSSFWorkbook(inputStream);} else if (excelFilePath.endsWith("xls")) {workbook = new HSSFWorkbook(inputStream);} else {throw new IllegalArgumentException("The specified file is not an Excel file");}return workbook;}private static String getCellValue(Cell cell) {//DataFormatter formatter = new DataFormatter();String formatPattern = "yyyy-MM-dd HH:mm:ss"; // 自定義日期時間格式//FormulaEvaluator evaluator = cell.getSheet().getWorkbook().getCreationHelper().createFormulaEvaluator();switch (cell.getCellType()) {case STRING:return cell.getRichStringCellValue().getString();case NUMERIC:if (DateUtil.isCellDateFormatted(cell)) {Date date = cell.getDateCellValue();DateFormat dateFormat = new SimpleDateFormat(formatPattern);return dateFormat.format(date);} else {return Double.toString(cell.getNumericCellValue());}case BOOLEAN:return Boolean.toString(cell.getBooleanCellValue());case FORMULA:return cell.getCellFormula();default:return "";}}

測試

    public static void main(String[] args) {String excelFilePath = "D:\\我是excel文件.xlsx";String csvFilePath = "D:\\我是csv文件.csv";try {convertExcelToCSV(excelFilePath, csvFilePath);System.out.println("Excel file converted to CSV successfully!");} catch (IOException e) {e.printStackTrace();}}

以上為整合保留時間格式需求的全部代碼，親測非常好用！