要实现Java中的Excel导入导出功能，可以使用Apache POI库。

下面是一个简单的示例：

1. 导入Excel文件：

import org.apache.poi.ss.usermodel.*;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;
import java.io.FileInputStream;
import java.io.IOException;
public class ExcelImportExample {
    public static void main(String[] args) {
        String filePath = "data.xlsx";
        try (FileInputStream fis = new FileInputStream(filePath);
             Workbook workbook = new XSSFWorkbook(fis)) {
            Sheet sheet = workbook.getSheetAt(0);
            for (Row row : sheet) {
                for (Cell cell : row) {
                    CellType cellType = cell.getCellType();
                    if (cellType == CellType.STRING) {
                        System.out.print(cell.getStringCellValue() + "\t");
                    } else if (cellType == CellType.NUMERIC) {
                        System.out.print(cell.getNumericCellValue() + "\t");
                    } else if (cellType == CellType.BOOLEAN) {
                        System.out.print(cell.getBooleanCellValue() + "\t");
                    }
                }
                System.out.println();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

2. 导出Excel文件：

import org.apache.poi.ss.usermodel.*;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;
import java.io.FileOutputStream;
import java.io.IOException;
public class ExcelExportExample {
    public static void main(String[] args) {
        String filePath = "data.xlsx";
        try (Workbook workbook = new XSSFWorkbook();
             FileOutputStream fos = new FileOutputStream(filePath)) {
            Sheet sheet = workbook.createSheet("Sheet 1");
            Row headerRow = sheet.createRow(0);
            headerRow.createCell(0).setCellValue("Name");
            headerRow.createCell(1).setCellValue("Age");
            headerRow.createCell(2).setCellValue("Gender");
            Row dataRow1 = sheet.createRow(1);
            dataRow1.createCell(0).setCellValue("John");