Java 读取 Excel 文件：解析 3124.xlsx 并转换数据格式

以下是读取Excel文件并转换数据格式的示例代码：

import java.io.FileInputStream;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;

import org.apache.poi.ss.usermodel.*;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;

public class ExcelReader {

    public static void main(String[] args) {
        String filePath = "C:\\Users\\25346\\Desktop\\3124.xlsx";

        List<CardAttenDence> cardAttenDenceList = readExcel(filePath);
        for (CardAttenDence cardAttenDence : cardAttenDenceList) {
            System.out.println("CardID: " + cardAttenDence.getCardID());
            System.out.println("AttenDatatime: " + cardAttenDence.getAttenDatatime());
            System.out.println();
        }
    }

    public static List<CardAttenDence> readExcel(String filePath) {
        List<CardAttenDence> cardAttenDenceList = new ArrayList<>();

        try (FileInputStream fis = new FileInputStream(filePath);
             Workbook workbook = new XSSFWorkbook(fis)) {

            Sheet sheet = workbook.getSheetAt(0);

            Row headerRow = sheet.getRow(0);
            int cardIDColumnIndex = -1;
            int attenDatatimeColumnIndex = -1;

            for (Cell cell : headerRow) {
                String columnName = cell.getStringCellValue().trim();
                if (columnName.equalsIgnoreCase("CardID")) {
                    cardIDColumnIndex = cell.getColumnIndex();
                } else if (columnName.equalsIgnoreCase("AttenDatatime")) {
                    attenDatatimeColumnIndex = cell.getColumnIndex();
                }
            }

            if (cardIDColumnIndex == -1 || attenDatatimeColumnIndex == -1) {
                throw new IllegalArgumentException("Invalid column name");
            }

            for (int i = 1; i <= sheet.getLastRowNum(); i++) {
                Row row = sheet.getRow(i);

                Cell cardIDCell = row.getCell(cardIDColumnIndex);
                Cell attenDatatimeCell = row.getCell(attenDatatimeColumnIndex);

                String cardID = readCellValueAsString(cardIDCell);
                String attenDatatime = readCellValueAsString(attenDatatimeCell);

                cardAttenDenceList.add(new CardAttenDence(cardID, attenDatatime));
            }

        } catch (IOException e) {
            e.printStackTrace();
        }

        return cardAttenDenceList;
    }

    public static String readCellValueAsString(Cell cell) {
        if (cell == null) {
            return "";
        }

        if (cell.getCellType() == CellType.STRING) {
            return cell.getStringCellValue().trim();
        } else if (cell.getCellType() == CellType.NUMERIC) {
            if (DateUtil.isCellDateFormatted(cell)) {
                Date date = cell.getDateCellValue();
                SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
                return formatter.format(date);
            } else {
                return String.valueOf((int) cell.getNumericCellValue());
            }
        } else {
            return "";
        }
    }

}

class CardAttenDence {
    private String cardID;
    private String attenDatatime;

    public CardAttenDence(String cardID, String attenDatatime) {
        this.cardID = cardID;
        this.attenDatatime = attenDatatime;
    }

    public String getCardID() {
        return cardID;
    }

    public String getAttenDatatime() {
        return attenDatatime;
    }
}

请注意，此示例假定您已经添加了 Apache POI 库以处理 Excel 文件。