我需要一段java excel导入导出的代码

好的，以下是Java中使用Apache POI库进行Excel导入导出的代码示例：

导入：

try {
    FileInputStream file = new FileInputStream(new File("path/to/excel.xlsx"));
    XSSFWorkbook workbook = new XSSFWorkbook(file);
    XSSFSheet sheet = workbook.getSheetAt(0);
    Iterator<Row> rowIterator = sheet.iterator();
    while (rowIterator.hasNext()) {
        Row row = rowIterator.next();
        Iterator<Cell> cellIterator = row.cellIterator();
        while (cellIterator.hasNext()) {
            Cell cell = cellIterator.next();
            switch (cell.getCellType()) {
                case STRING:
                    System.out.print(cell.getStringCellValue() + "\t");
                    break;
                case NUMERIC:
                    System.out.print(cell.getNumericCellValue() + "\t");
                    break;
                case BOOLEAN:
                    System.out.print(cell.getBooleanCellValue() + "\t");
                    break;
                default:
            }
        }
        System.out.println();
    }
    file.close();
} catch (Exception e) {
    e.printStackTrace();
}

导出：

XSSFWorkbook workbook = new XSSFWorkbook();
XSSFSheet sheet = workbook.createSheet("Sheet1");
Map<String, Object[]> data = new TreeMap<String, Object[]>();
data.put("1", new Object[]{"ID", "NAME", "LASTNAME"});
data.put("2", new Object[]{1, "John", "Doe"});
data.put("3", new Object[]{2, "Jane", "Doe"});
data.put("4", new Object[]{3, "Jack", "Doe"});
data.put("5", new Object[]{4, "Jill", "Doe"});
Set<String> keyset = data.keySet();
int rownum = 0;
for (String key : keyset) {
    Row row = sheet.createRow(rownum++);
    Object[] objArr = data.get(key);
    int cellnum = 0;
    for (Object obj : objArr) {
        Cell cell = row.createCell(cellnum++);
        if (obj instanceof String)
            cell.setCellValue((String) obj);
        else if (obj instanceof Integer)
            cell.setCellValue((Integer) obj);
    }
}
try {
    FileOutputStream out = new FileOutputStream(new File("path/to/excel.xlsx"));
    workbook.write(out);
    out.close();
    System.out.println("Excel written successfully..");
} catch (Exception e) {
    e.printStackTrace();
}