java - 使用 Apache POI 在 java 中读取 excel (xlsx) 文件(得到奇怪的数字)

Question

我必须为学校项目打开一个测试日期。该测试日期是一个 excel(xlsx) 文件，其中包含数字、字母、日期和时间。但是使用下面的代码它读取excel文件，但我得到奇怪的数字，例如42538.0和1.153481443E9。日期之后。

public class Page4_Controller implements Initializable {

    @FXML
    private Button button1;

    public void Button1Action(ActionEvent event) throws IOException {
        //Initialize excel file
        FileChooser fc = new FileChooser();
        fc.getExtensionFilters().addAll(
                new ExtensionFilter("Excel Files", "*.xlsx"));
        File selectedFile = fc.showOpenDialog(null);

        // Read file
        readXLSXFile(selectedFile.getAbsolutePath());
    }

    public static void readXLSXFile(String excelFilePath) throws IOException {
        FileInputStream fys = new FileInputStream(new File(excelFilePath));

        //Create workbook instance that refers to .xlsx file
        XSSFWorkbook wb = new XSSFWorkbook(fys);

        //Create a sheet object to retrive the sheet
        XSSFSheet sheet = wb.getSheetAt(0);

        //That is for evalueate the cell type
        FormulaEvaluator forlulaEvaluator = wb.getCreationHelper().createFormulaEvaluator();
        DataFormatter df = new DataFormatter();

        //Default data for database (comes later)
        //String airport = sheet.getRow(1).getCell(1).getStringCellValue();
        //Date date = sheet.getRow(2).getCell(1).getDateCellValue();

        for (Row row : sheet) {
            for (Cell cell : row) {
                switch (forlulaEvaluator.evaluateInCell(cell).getCellType()) {
                    //If cell is a numeric format
                    case Cell.CELL_TYPE_NUMERIC:
                        System.out.print(cell.getNumericCellValue() + "\t");
                        System.out.print(df.formatCellValue(cell) + "\t");
                        break;
                    //If cell is a string format
                    case Cell.CELL_TYPE_STRING:
                        System.out.print(cell.getRichStringCellValue() + "\t");
                        break;
                }

            }
            System.out.println();
        }
    }

    @Override
    public void initialize(URL location, ResourceBundle resources) {
    }

}

Answer 1

日期在 Excel 内部存储为 double 值，并且 DataFormatter.formatCellValue(Cell cell) 以字符串形式返回单元格的格式化值，无论单元格类型如何。因此，当您调用 df.formatCellValue(cell) 时，您将以字符串形式返回单元格的 double 值。

要将单元格值打印为日期，代码如下:

switch (cell.getCellType()) {
    // ...
    case CellType.NUMERIC:
        // Check if a cell contains a date. Since dates are stored internally in Excel as double values we infer it is a date if it is formatted as such.
        if (DateUtil.isCellDateFormatted(cell)) {
            // Get the value of the cell as a date. Returns a java.util.Date.
            System.out.println(cell.getDateCellValue());
        } else {
            System.out.println(cell.getNumericCellValue());
        }
    // ...
}

来源:

• https://poi.apache.org/spreadsheet/quick-guide.html#CellContents
• https://poi.apache.org/apidocs/org/apache/poi/ss/usermodel/DataFormatter.html
• https://poi.apache.org/apidocs/org/apache/poi/ss/usermodel/Cell.html
• https://poi.apache.org/apidocs/org/apache/poi/ss/usermodel/DateUtil.html

编辑

仅包含时间的 Excel 单元格的日期部分固定为 1899 年 12 月 31 日。您可以使用此信息来检查单元格是时间还是日期:提取年份，如果是 1899 年，则它是时间单元格。

SimpleDateFormat timeFormat = new SimpleDateFormat("HH:mm");
SimpleDateFormat yearFormat = new SimpleDateFormat("yyyy");
SimpleDateFormat dateFormat = new SimpleDateFormat("dd-MM-yyyy");

switch (cell.getCellType()) {

  case CellType.NUMERIC:
    if (DateUtil.isCellDateFormatted(cell)) {
        Date dateCellValue = cell.getDateCellValue();
        String year = yearFormat.format(dateCellValue);
        if (year.equals("1899")) 
          System.out.println(timeFormat.format(dateCellValue));
        else
          System.out.println(dateFormat.format(dateCellValue));
    } else {
        System.out.println(cell.getNumericCellValue());
    }

}