Пример кода

gistfile1.txt

public static void writeTransactionToXml(Context context, Transaction transaction, List<Document> documents) {
        boolean fileCreatedNow = false;
        String date = transaction.getDate();
        String customerName = transaction.getCustomerName();


        if (!FUtils.isFileExists(context, FileProvider.TRANSACTION_HISTORY)) {
            fileCreatedNow = true;
        }

        File encryptedFolder = context.getDir(FileProvider.ENCRYPTED_DATA, Context.MODE_PRIVATE);
        File[] files = encryptedFolder.listFiles((dir, name) -> name.equals(FileProvider.TRANSACTION_HISTORY));

        File transactionFile;

        if (fileCreatedNow) {
            transactionFile = new File(encryptedFolder, FileProvider.TRANSACTION_HISTORY);
            try {
                boolean createdTransaction = transactionFile.createNewFile();
                Log.i(TAG, String.valueOf(createdTransaction));
            } catch (IOException e) {
                Log.e(XmlUtils.TAG, "Creating transactionFile", e);
            }
        } else {
            transactionFile = files[0];
        }

        AESLocalStorageUtils aesLocalStorageUtils = new AESLocalStorageUtils();

        byte[] fileBytes = FUtils.readFile(transactionFile);

        if (!fileCreatedNow)
            fileBytes = aesLocalStorageUtils.decrypt(fileBytes);

        try (FileOutputStream fileOutputStream = new FileOutputStream(transactionFile, false)) {
            fileOutputStream.write(fileBytes);
        } catch (IOException e) {
            Log.e(XmlUtils.class.getSimpleName(), AESLocalStorageUtils.EXCEPTION_DURING_DECRYPT, e);
        }


        try (RandomAccessFile raf = new RandomAccessFile(transactionFile, "rw")) {
            XmlSerializer xmlSerializer = Xml.newSerializer();
            StringWriter writer = new StringWriter();
            xmlSerializer.setOutput(writer);
            if (fileCreatedNow) {
                xmlSerializer.startDocument("UTF-8", true);
                xmlSerializer.startTag(null, TRANSACTIONS);
            }
            xmlSerializer.startTag(null, TRANSACTION);
            //process customer name tag
            xmlSerializer.startTag(null, CUSTOMER_NAME);
            xmlSerializer.text(customerName);
            xmlSerializer.endTag(null, CUSTOMER_NAME);
            //process date tag
            xmlSerializer.startTag(null, DATE);
            xmlSerializer.text(date);
            xmlSerializer.endTag(null, DATE);

            //process Documents Tag
            xmlSerializer.startTag(null, DOCUMENTS);

            for (Document document : documents) {
                xmlSerializer.startTag(null, DOCUMENT);
                for (Map.Entry<String, String> mrz : document.getXmlPersonData().getMrz().entrySet()) {
                    xmlSerializer.startTag(null, mrz.getKey());
                    xmlSerializer.text(mrz.getValue());
                    xmlSerializer.endTag(null, mrz.getKey());
                }
                xmlSerializer.startTag(null, FACE_FROM_DOC_IMAGE);
                processImageBase64(xmlSerializer, document.getFacePhotoFromDocument());
                xmlSerializer.endTag(null, FACE_FROM_DOC_IMAGE);

                xmlSerializer.startTag(null, FIRST_DOC_IMAGE);
                processImageBase64(xmlSerializer, document.getFirstDocumentPhoto());
                xmlSerializer.endTag(null, FIRST_DOC_IMAGE);

                xmlSerializer.startTag(null, SECOND_DOC_IMAGE);
                processImageBase64(xmlSerializer, document.getSecondDocumentPhoto());
                xmlSerializer.endTag(null, SECOND_DOC_IMAGE);

                xmlSerializer.endTag(null, DOCUMENT);
            }

            xmlSerializer.endTag(null, DOCUMENTS);

            xmlSerializer.endTag(null, TRANSACTION);

            xmlSerializer.endDocument();
            xmlSerializer.flush();
            String dataWrite = writer.toString();
            if (!fileCreatedNow) {
                raf.seek(raf.length() - TRANSACTION_END_TAG_LENGTH);
            }
            raf.write(dataWrite.getBytes());
            if (!fileCreatedNow) {
                raf.writeBytes(TRANSACTIONS_END);
            }


            fileBytes = aesLocalStorageUtils.encrypt(FUtils.readFile(transactionFile));

            try (FileOutputStream fileOutputStream = new FileOutputStream(transactionFile, false)) {
                fileOutputStream.write(fileBytes);
            } catch (IOException er) {
                Log.e(XmlUtils.class.getSimpleName(), AESLocalStorageUtils.EXCEPTION_DURING_DECRYPT, er);
            }


        } catch (FileNotFoundException e) {
            Log.e(TAG, "FileNotFound", e);
        } catch (IllegalArgumentException e) {
            Log.e(TAG, "IllegalArgument", e);
        } catch (IllegalStateException e) {
            Log.e(TAG, "IllegalState", e);
        } catch (IOException e) {
            Log.e(TAG, "IOException", e);
        }
    }