POIでファイルにパスワード

App.java

package sample.poi;

import java.io.FileOutputStream;
import java.io.OutputStream;

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;

public class App {
	public static void main(String[] args) throws Exception {
		POIFSFileSystem fs = new POIFSFileSystem();
		EncryptionInfo info = new EncryptionInfo(fs, EncryptionMode.agile);

		Encryptor enc = info.getEncryptor();
		enc.confirmPassword("foobaa");

		OPCPackage opc = OPCPackage.open("/path/to/file");
		OutputStream os = enc.getDataStream(fs);
		opc.save(os);
		opc.close();

		FileOutputStream fos = new FileOutputStream("/path/to/encfile");
		fs.writeFilesystem(fos);
		fos.close();
	}
}