Create a password protected excel file using apache poi?

I've often found with POI that to do more complex stuff, a useful approach is to create the spreadsheet in Excel with the advanced features (e.g. macros), then use POI to read the spreadsheet, populate it and write it out. POI will normally maintain the spreadsheet features and add the data.

I've not tried this for passwords, but I suspect it's worth an experiment.

See the busy developer's guide for more info.

It's an old question but if anyone still needs it-

Create a password protected excel file or use an existing template and make it password protected. This will give the users a "read only" access though. Here's an example where I have an excel file that has a password "secret"-

import java.io.BufferedInputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import org.apache.poi.hssf.record.crypto.Biff8EncryptionKey;
import org.apache.poi.hssf.usermodel.HSSFRow;
import org.apache.poi.hssf.usermodel.HSSFSheet;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.poifs.filesystem.POIFSFileSystem;
import org.apache.poi.ss.usermodel.Cell;

public class ProtectedExcelFile { 

    public static void main(final String... args) throws Exception {     

        String fname = "C:\\Documents and Settings\\sadutta\\Desktop\\sample.xls";

        FileInputStream fileInput = null;       
        BufferedInputStream bufferInput = null;      
        POIFSFileSystem poiFileSystem = null;    
        FileOutputStream fileOut = null;

        try {           

            fileInput = new FileInputStream(fname);         
            bufferInput = new BufferedInputStream(fileInput);            
            poiFileSystem = new POIFSFileSystem(bufferInput);            

            Biff8EncryptionKey.setCurrentUserPassword("secret");            
            HSSFWorkbook workbook = new HSSFWorkbook(poiFileSystem, true);            
            HSSFSheet sheet = workbook.getSheetAt(0);           

            HSSFRow row = sheet.createRow(0);
            Cell cell = row.createCell(0);

            cell.setCellValue("THIS WORKS!"); 

            fileOut = new FileOutputStream(fname);
            workbook.writeProtectWorkbook(Biff8EncryptionKey.getCurrentUserPassword(), "");
            workbook.write(fileOut);



        } catch (Exception ex) {

            System.out.println(ex.getMessage());      

        } finally {         

              try {            

                  bufferInput.close();     

              } catch (IOException ex) {

                  System.out.println(ex.getMessage());     

              }    

              try {            

                  fileOut.close();     

              } catch (IOException ex) {

                  System.out.println(ex.getMessage());     

              } 
        }       

    }
}

The same way you should be able to write or modify the existing template that you have. After you are done, overwrite the template. If your template should be used many times, you may want to copy the template to some other location and then use the code to modify it.