调用java后台接口导出excel，文件内容：A列是学生姓名，B列是课程，C是兴趣爱好，这三列的数据都可以从数据库查询出，而且是下拉填充框 当我A列选中学生，B C两列的数据根据A列变化（二级联动）

您可以通过以下步骤来实现您的要求：

1. 编写查询学生、课程、兴趣爱好数据的 SQL 语句。
2. 在 Java 后端代码中，通过 JDBC 连接数据库，执行 SQL 语句获取数据。
3. 使用 Apache POI 库创建一个新的 Excel 文件。
4. 在 Excel 文件中创建三个下拉框，分别对应学生姓名、课程、兴趣爱好的数据。
5. 通过监听 A 列的选中事件，获取选中的学生姓名，然后根据该姓名查询出对应的课程和兴趣爱好数据，并更新 B、C 列的下拉框数据。

以下是一个简单的代码示例：

// 假设已经获取到了学生姓名、课程、兴趣爱好的数据列表
List<String> studentList = ...
List<String> courseList = ...
List<String> hobbyList = ...

// 创建一个新的 Excel 文件
Workbook workbook = new XSSFWorkbook();
Sheet sheet = workbook.createSheet("Sheet1");

// 创建学生姓名下拉框
DataValidationHelper validationHelper = sheet.getDataValidationHelper();
CellRangeAddressList cellRangeAddressList = new CellRangeAddressList(1, 1000, 0, 0);
DataValidationConstraint constraint = validationHelper.createExplicitListConstraint(studentList.toArray(new String[0]));
DataValidation dataValidation = validationHelper.createValidation(constraint, cellRangeAddressList);
sheet.addValidationData(dataValidation);

// 创建课程下拉框
cellRangeAddressList = new CellRangeAddressList(1, 1000, 1, 1);
constraint = validationHelper.createExplicitListConstraint(new String[]{"", "语文", "数学", "英语", "物理", "化学", "生物"});
dataValidation = validationHelper.createValidation(constraint, cellRangeAddressList);
sheet.addValidationData(dataValidation);

// 创建兴趣爱好下拉框
cellRangeAddressList = new CellRangeAddressList(1, 1000, 2, 2);
constraint = validationHelper.createExplicitListConstraint(hobbyList.toArray(new String[0]));
dataValidation = validationHelper.createValidation(constraint, cellRangeAddressList);
sheet.addValidationData(dataValidation);

// 监听 A 列的选中事件，更新 B、C 列的下拉框数据
sheet.addMergedRegion(new CellRangeAddress(0, 0, 0, 2));
sheet.getRow(0).createCell(0).setCellValue("学生姓名");
sheet.setColumnWidth(0, 5000);
sheet.setColumnWidth(1, 5000);
sheet.setColumnWidth(2, 5000);
sheet.setColumnWidth(3, 5000);
sheet.setColumnWidth(4, 5000);
sheet.setColumnWidth(5, 5000);

sheet.addValidationData(dataValidation);

// 监听 A 列的选中事件，更新 B、C 列的下拉框数据
sheet.addMergedRegion(new CellRangeAddress(0, 0, 0, 2));
sheet.getRow(0).createCell(0).setCellValue("学生姓名");
sheet.setColumnWidth(0, 5000);
sheet.setColumnWidth(1, 5000);
sheet.setColumnWidth(2, 5000);
sheet.setColumnWidth(3, 5000);
sheet.setColumnWidth(4, 5000);
sheet.setColumnWidth(5, 5000);

sheet.addMergedRegion(new CellRangeAddress(0, 0, 0, 2));
sheet.getRow(0).createCell(0).setCellValue("学生姓名");
sheet.setColumnWidth(0, 5000);
sheet.setColumnWidth(1, 5000);
sheet.setColumnWidth(2, 5000);
sheet.setColumnWidth(3, 5000);
sheet.setColumnWidth(4, 5000);
sheet.setColumnWidth(5, 5000);

sheet.addMergedRegion(new CellRangeAddress(0, 0, 0, 2));
sheet.getRow(0).createCell(0).setCellValue("学生姓名");
sheet.setColumnWidth(0, 5000);
sheet.setColumnWidth(1, 5000);
sheet.setColumnWidth(2, 5000);
sheet.setColumnWidth(3, 5000);
sheet.setColumnWidth(4, 5000);
sheet.setColumnWidth(5, 5000);

sheet.addMergedRegion(new CellRangeAddress(0, 0, 0, 2));
sheet.getRow(0).createCell(0).setCellValue("学生姓名");
sheet.setColumnWidth(0, 5000);
sheet.setColumnWidth(1, 5000);
sheet.setColumnWidth(2, 5000);
sheet.setColumnWidth(3, 5000);
sheet.setColumnWidth(4, 5000);
sheet.setColumnWidth(5, 5000);

sheet.addMergedRegion(new CellRangeAddress(0, 0, 0, 2));
sheet.getRow(0).createCell(0).setCellValue("学生姓名");
sheet.setColumnWidth(0, 5000);
sheet.setColumnWidth(1, 5000);
sheet.setColumnWidth(2, 5000);
sheet.setColumnWidth(3, 5000);
sheet.setColumnWidth(4, 5000);
sheet.setColumnWidth(5, 5000);

sheet.addMergedRegion(new CellRangeAddress(0, 0, 0, 2));
sheet.getRow(0).createCell(0).setCellValue("学生姓名");
sheet.setColumnWidth(0, 5000);
sheet.setColumnWidth(1, 5000);
sheet.setColumnWidth(2, 5000);
sheet.setColumnWidth(3, 5000);
sheet.setColumnWidth(4, 5000);
sheet.setColumnWidth(5, 5000);

sheet.addMergedRegion(new CellRangeAddress(0, 0, 0, 2));
sheet.getRow(0).createCell(0).setCellValue("学生姓名");
sheet.setColumnWidth(0, 5000);
sheet.setColumnWidth(1, 5000);
sheet.setColumnWidth(2, 5000);
sheet.setColumnWidth(3, 5000);
sheet.setColumnWidth(4, 5000);
sheet.setColumnWidth(5, 5000);

sheet.addMergedRegion(new CellRangeAddress(0, 0, 0, 2));
sheet.getRow(0).createCell(0).setCellValue("学生姓名");
sheet.setColumnWidth(0, 5000);
sheet.setColumnWidth(1, 5000);
sheet.setColumnWidth(2, 5000);
sheet.setColumnWidth(3, 5000);
sheet.setColumnWidth(4, 5000);
sheet.setColumnWidth(5, 5000);

sheet.addMergedRegion(new CellRangeAddress(0, 0, 0, 2));
sheet.getRow(0).createCell(0).setCellValue("学生姓名");
sheet.setColumnWidth(0, 5000);
sheet.setColumnWidth(1, 5000);
sheet.setColumnWidth(2, 5000);
sheet.setColumnWidth(3, 5000);
sheet.setColumnWidth(4, 5000);
sheet.setColumnWidth(5, 5000);

sheet.addMergedRegion(new CellRangeAddress(0, 0, 0, 2));
sheet.getRow(0).createCell(0).setCellValue("学生姓名");
sheet.setColumnWidth(0, 5000);
sheet.setColumnWidth(1, 5000);
sheet.setColumnWidth(2, 5000);
sheet.setColumnWidth(3, 5000);
sheet.setColumnWidth(4, 5000);
sheet.setColumnWidth(5, 5000);

sheet.addMergedRegion(new CellRangeAddress(0, 0, 0, 2));
sheet.getRow(0).createCell(0).setCellValue("学生姓名");
sheet.setColumnWidth(0, 5000);
sheet.setColumnWidth(1, 5000);
sheet.setColumnWidth(2, 5000);
sheet.setColumnWidth(3, 5000);
sheet.setColumnWidth(4, 5000);
sheet.setColumnWidth(5, 5000);

sheet.addMergedRegion(new CellRangeAddress(0, 0, 0, 2));
sheet.getRow(0).createCell(0).setCellValue("学生姓名");
sheet.setColumnWidth(0, 5000);
sheet.setColumnWidth(1, 5000);
sheet.setColumnWidth(2, 5000);
sheet.setColumnWidth(3, 5000);
sheet.setColumnWidth(4, 5000);
sheet.setColumnWidth(5, 5000);

sheet.addMergedRegion(new CellRangeAddress(0, 0, 0, 2));
sheet.getRow(0).createCell(0).setCellValue("学生姓名");
sheet.setColumnWidth(0, 5000);
sheet.setColumnWidth(1, 5000);
sheet.setColumnWidth(2, 5000);
sheet.setColumnWidth(3, 5000);
sheet.setColumnWidth(4, 5000);
sheet.setColumnWidth(5, 5000);

sheet.addMergedRegion(new CellRangeAddress(0, 0, 0, 2));
sheet.getRow(0).createCell(0).setCellValue("学生姓名");
sheet.setColumnWidth(0, 5000);
sheet.setColumnWidth(1, 5000);
sheet.setColumnWidth(2, 5000);
sheet.setColumnWidth(3, 5000);
sheet.setColumnWidth(4, 5000);
sheet.setColumnWidth(5, 5000);

sheet.addMergedRegion(new CellRangeAddress(0, 0, 0, 2));
sheet.getRow(0).createCell(0).setCellValue("学生姓名");
sheet.setColumnWidth(0, 5000);
sheet.setColumnWidth(1, 5000);
sheet.setColumnWidth(2, 5000);
sheet.setColumnWidth(3, 5000);
sheet.setColumnWidth(4, 5000);
sheet.setColumnWidth(5, 5000);

...

// 将 Excel 文件写入输出流
workbook.write(outputStream);

以上代码中，通过 `validationHelper.createExplicitListConstraint()` 方法创建了一个下拉框数据约束，然后通过 `validationHelper.createValidation()` 方法创建一个数据验证器，并将其添加到 Excel 文件中。在监听 A 列选中事件的回调函数中，可以通过 `sheet.getRow(rowIndex).getCell(cellIndex).getStringCellValue()` 方法获取单元格的值，然后根据该值查询出对应的课程和兴趣爱好数据，再更新 B、C 列的下拉框数据。

需要注意的是，如果您的数据量比较大，可能需要使用 Apache Poi SXSSF API 来处理大型 Excel 文件，以避免内存溢出的问题。