导出文件夹内的数据

我正在使用以下代码导出数据。

public void onClick(View v) {
    File sd = Environment.getExternalStorageDirectory();
    String csvFile = "expensesData.xls";
    File directory = new File(sd.getAbsolutePath());
    //create directory if not exist
    if (!directory.isDirectory()) {
        directory.mkdirs();
    }
    try {

        //file path
        File file = new File(directory, csvFile);
        WorkbookSettings wbSettings = new WorkbookSettings();
        WritableWorkbook workbook;
        workbook = Workbook.createWorkbook(file, wbSettings);
        //Excel sheet name. 0 represents first sheet
        WritableSheet sheet = workbook.createSheet("userList", 0);
        // column and row
        sheet.addCell(new Label(0, 0, "Type"));
        sheet.addCell(new Label(1, 0, "Amount"));
        Cursor cursor = db.rawQuery("SELECT expenses_type,amount" +
                "FROM expenses_diary", null);
        if (cursor.moveToFirst()) {
            do {
                String ex_type = cursor.getString(cursor.getColumnIndex("expenses_type"));
                String ex_amount = cursor.getString(cursor.getColumnIndex("amount"));
                int i = cursor.getPosition() + 1;
                sheet.addCell(new Label(0, i, ex_type));
                sheet.addCell(new Label(1, i, ex_amount));
            } while (cursor.moveToNext());
        }
        cursor.close();
        workbook.write();
        workbook.close();
        showToast("Exporting...");
        showToast("Data Exported - expensesData.xls");
    } catch (WriteException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
   }
});

导出的文件存储在内部存储的根目录中，但我想将该文件存储在文件夹中。（例如，当前在/expensesData.xls，但是我想要）ExpensesApp/expensesData.xls。

我认为这很简单，但是是android中的新功能，所以我不知道。