如何在 Flutter 中使用密码保护 PDF？

Question

我在 Flutter 中开发了一项将个人联系人和数据导出为 PDF 的功能，我想在将数据导出到他/她的电子邮件时使用用户设置的密码或 PIN 码来保护该数据。一切都已设置并且工作正常，但我找不到为导出的 PDF 设置密码的方法。 这是我的小部件代码，我使用的是 PDF 包 3.8.1。

import 'package:pdf/widgets.dart' as pw;
import 'package:pdf/widgets.dart' show Font;
import 'package:pdf/widgets.dart' as pwFonts;
import 'package:open_file/open_file.dart';
import 'package:path_provider/path_provider.dart';

class PdfApi {
static Future<File> generateCenteredText() async{
final pdf = pw.Document();
pdf.addPage(My PDF Content here...);
return saveDocument(name: 'Personal Records.pdf', pdf: pdf);
}

static Future<File> saveDocument({
    required String name,
    required pw.Document pdf,
  }) async {
    final bytes = await pdf.save();
    final dir = await getApplicationDocumentsDirectory();
    final file = File('${dir.path}/$name');
    await file.writeAsBytes(bytes);
     // secure the File with a PASSWORD or PIN code HERE....
    return file;
  }

}

我想要一种方法，在通过电子邮件发送文件之前，在 Flutter 中使用密码来加密/保护文件。

Answer 1

要使用来自syncfusion_flutter_pdf和pdf的包在Flutter中使用密码加密PDF，请按照以下步骤操作：

使用pdf包生成pdf并使用syncfusion_flutter_pdf设置密码 用于 pdf。

import 'package:path_provider/path_provider.dart';
import 'package:pdf/pdf.dart';
import 'package:pdf/widgets.dart' as pw;
import 'package:open_file/open_file.dart';
import 'package:syncfusion_flutter_pdf/pdf.dart' as syncfusionPdf;

 //Generate Uint8List of your pdf created using pdf package
 final pdfBytes = await pdf.save();
 await securePdfWithPassword(pdfBytes);


 //Use the Below functions to set password by passing your generated pdf 
 //file to this function in Uint8List format

 Future<void> securePdfWithPassword(List<int> pdfBytes) async {
  //Load the existing PDF document.
  syncfusionPdf.PdfDocument document = syncfusionPdf.PdfDocument(
   inputBytes: pdfBytes,
  );
  document.security.userPassword = 'your_user_password';
  document.security.ownerPassword = 'your_owner_password';
  //Set the encryption algorithm.
  document.security.algorithm = 
  syncfusionPdf.PdfEncryptionAlgorithm.aesx256Bit;
  document.security.permissions.addAll([
    syncfusionPdf.PdfPermissionsFlags.print,
    syncfusionPdf.PdfPermissionsFlags.copyContent
  ]);
  List<int> securedBytes = await document.save();
  document.dispose();
  //Save the file and launch/download.
  saveAndLaunchFile(securedBytes, 'genrated_pdf.pdf');
 }

//Save secured pdf and launch it
Future<void> saveAndLaunchFile(List<int> bytes, String fileName) async {
  Directory directory = await getApplicationSupportDirectory();
  String path = directory.path;
  File file = File('$path/$fileName');
  await file.writeAsBytes(bytes, flush: true);
  //Open the secured Pdf File
  OpenFile.open('$path/$fileName');
 }