使用Java从p7s文件中提取内容

Question

我使用此代码将文件提取到p7s文件中。

 try{


                byte[] buffer = new byte[(int) novo.length()];
                DataInputStream in = new DataInputStream(new FileInputStream(novo));
                in.readFully(buffer);
                in.close();

                //Corresponding class of signed_data is CMSSignedData
                CMSSignedData signature = new CMSSignedData(buffer);
                Store cs = signature.getCertificates();
                SignerInformationStore signers = signature.getSignerInfos();
                Collection c = signers.getSigners();
                Iterator it = c.iterator();

                //the following array will contain the content of xml document
                byte[] data = null;

                while (it.hasNext()) {
                    SignerInformation signer = (SignerInformation) it.next();
//                    Collection certCollection = cs.getMatches(signer.getSID());
//                    Iterator certIt = certCollection.iterator();
//                    X509CertificateHolder cert = (X509CertificateHolder) certIt.next();

                    CMSProcessable sc = signature.getSignedContent();
                    data = (byte[]) sc.getContent();
                }
                FileUtils.writeByteArrayToFile(new File(recuperarPasta(numeroProtocolo, especialidade, Diretorio.PROTOCOLO, null, tipoProtocolo) + numeroProtocolo +".PDF"), data);
            }catch (Exception e ){
                throw new IOException(e.getMessage());
            }

但是对于大文件，我有一个堆空间，如何使用输出流提取文件？

tks