I want to Create a password protected excel file using Apache POI, and then give to for download to Servlet.getOutputStream()

问题

I don't have permission to save files to the filesystem. All the examples I could find online are using filesystem.

I want to create workbook in memory as below:

HSSFWorkbook workbook = new HSSFWorkbook();

Write data to workbook... Make the workbook password protected.?

Then write the workbook to output stream as below:

workbook.write(servlet.getOutputStream());

回答1:

I was able to get the following to work with an HttpServlet and HSSFWorkbook .xls file - WorkbookServlet.java:

package com.joshden;

import java.io.IOException;
import java.io.OutputStream;

import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.poi.hssf.record.crypto.Biff8EncryptionKey;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.ss.usermodel.Workbook;

@WebServlet("/workbook")
public class WorkbookServlet extends HttpServlet {
    private static final long serialVersionUID = 4087954595439224462L;
    private static final String password = "foobar1";

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException {
        response.setContentType("application/vnd.ms-excel");
        response.addHeader("Content-Disposition", "attachment; filename=password_protected.xls");
        createAndWriteEncryptedWorkbook(response.getOutputStream());
    }

    private void createAndWriteEncryptedWorkbook(OutputStream requestOutputStream) throws IOException {
        HSSFWorkbook workbook = new HSSFWorkbook();
        populateWorkbook(workbook);
        Biff8EncryptionKey.setCurrentUserPassword(password);
        workbook.write(requestOutputStream);
        workbook.close();
    }

    private void populateWorkbook(Workbook workbook) {
        workbook.createSheet("TestSheet");
        // TODO create other sheets, populate cell values
    }

}

With requests to /workbook, the servlet creates the HSSF workbook in memory with a sheet named TestSheet. The password is set to "foobar1". It prompts the browser to download it as a file with the name password_protected.xls.

Also see Apache POI - Encryption support. Encryption for the binary formats (HSSF) has only been available since Apache POI 3.16. At the time of this writing, 3.16 hasn't been released yet, and I used 3.16-beta1 in my example.

The encyprtion support guide also has info for creating encrypted (password protected) .xlsx (XSSF) files. Here's an example I created that will prompt the file to be named password_protected.xlsx:

package com.joshden;

import java.io.IOException;
import java.io.OutputStream;
import java.security.GeneralSecurityException;

import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.poi.openxml4j.opc.OPCPackage;
import org.apache.poi.poifs.crypt.EncryptionInfo;
import org.apache.poi.poifs.crypt.EncryptionMode;
import org.apache.poi.poifs.crypt.Encryptor;
import org.apache.poi.poifs.filesystem.POIFSFileSystem;
import org.apache.poi.ss.usermodel.Workbook;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;

@WebServlet("/workbook")
public class WorkbookServlet extends HttpServlet {
    private static final long serialVersionUID = 4087954595439224462L;
    private static final String password = "foobar1";

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException {
        response.setContentType("application/vnd.openxmlformats-officedocument.spreadsheetml.sheet");
        response.addHeader("Content-Disposition", "attachment; filename=password_protected.xlsx");
        createAndWriteEncryptedWorkbook(response.getOutputStream());
    }

    private void createAndWriteEncryptedWorkbook(OutputStream requestOutputStream) throws IOException {
        XSSFWorkbook workbook = new XSSFWorkbook();
        OPCPackage opc = workbook.getPackage();
        populateWorkbook(workbook);

        try {
            POIFSFileSystem fileSystem = new POIFSFileSystem();
            opc.save(getEncryptingOutputStream(fileSystem, password));
            fileSystem.writeFilesystem(requestOutputStream);
        }
        finally {
            workbook.close();
        }
    }

    private void populateWorkbook(Workbook workbook) {
        workbook.createSheet("TestSheet");
        // TODO create other sheets, populate cell values
    }

    private OutputStream getEncryptingOutputStream(POIFSFileSystem fileSystem, String password) throws IOException {
        EncryptionInfo encryptionInfo = new EncryptionInfo(EncryptionMode.agile);
        Encryptor encryptor = encryptionInfo.getEncryptor();
        encryptor.confirmPassword(password);

        try {
            return encryptor.getDataStream(fileSystem);
        } 
        catch (GeneralSecurityException e) {
            // TODO handle this better
            throw new RuntimeException(e);
        }
    }

}

来源：https://stackoverflow.com/questions/41354454/i-want-to-create-a-password-protected-excel-file-using-apache-poi-and-then-give

标签

java

apache-poi