writing excel file with encryption in grails

Question

I have written a logic to download file in grails. For writing xls file i'm using ApachePOI. I wants to encrypt file with password and data should be encrypted after download completed. I have gone through ApachePOI encryption doc(https://poi.apache.org/encryption.html). but I didn't get any relevant information.

Answer 1

I managed to solve above problem. Insted of ".xls", now using ".xlsx". Dummy solution is as follow:

def encryptedFile(){
String fileName = "${name_of_xlsx_file}.xlsx"
response.setContentType('application/vnd.ms-excel')
response.setHeader("Content-disposition", "attachment; filename=${fileName}")
//Biff8EncryptionKey.setCurrentUserPassword("****");
XSSFWorkbook workbook = new XSSFWorkbook();
XSSFSheet sheet = workbook.createSheet("sheet_no_1");
XSSFRow rowhead = sheet.createRow((short) 0)
rowhead.createCell(0).setCellValue("Created On")
rowhead.createCell(1).setCellValue("Email")
rowhead.createCell(2).setCellValue("First Name")
rowhead.createCell(3).setCellValue("Last Name")
rowhead.createCell(4).setCellValue("Send Newsletter")
rowhead.createCell(5).setCellValue("Code")
{
 // worksheet writing logic goes here.....
}
ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
workbook.write(byteArrayOutputStream);
byteArrayOutputStream.close();
ByteArrayInputStream byteArrayInputStream = new 
ByteArrayInputStream(byteArrayOutputStream.toByteArray());
String password="password_to_set"
encrypt(byteArrayInputStream, response.outputStream, password);
byteArrayInputStream.close();   
}   
public static void encrypt(InputStream input, OutputStream output, String password)
throws IOException {
try {
POIFSFileSystem fs = new POIFSFileSystem();
EncryptionInfo info = new EncryptionInfo(EncryptionMode.agile);
Encryptor enc = info.getEncryptor();
enc.confirmPassword(password)
OPCPackage opc = OPCPackage.open(input);
OutputStream os = enc.getDataStream(fs);
opc.save(os);
opc.close();
fs.writeFilesystem(output);
output.close();
} catch (GeneralSecurityException e) {
throw new RuntimeException(e);
} catch (InvalidFormatException e) {
throw new RuntimeException(e);
}
}