尝试使用Flutter从Firebase下载PDF

如何解决尝试使用Flutter从Firebase下载PDF

我正在学习如何使用Flutter，并且在此.app中，我试图从firebase final imgUrl = manuais.data()['documento'];下载PDF文件，这是我用来从Firebase数据库获取链接的最终imgURL。>

这是错误：

I/flutter (12444): error is
I/flutter (12444): FileSystemException: Cannot open file,path = '/storage/emulated/0/Download/newtask1.pdf' (OS Error: Operation not permitted,errno = 1)

这是代码

import 'dart:typed_data';
import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:dio/dio.dart';
import 'package:ext_storage/ext_storage.dart';
import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:esys_flutter_share/esys_flutter_share.dart';
import 'dart:io';
import 'package:flutter_cached_pdfview/flutter_cached_pdfview.dart';
import 'package:permission_handler/permission_handler.dart';





class Home extends StatefulWidget {
  @override
  _HomeState createState() => _HomeState();
}

class _HomeState extends State<Home> {

  int _currentIndex = 0;






  final tabs = [

    //TAB DE MANUAIS
    Center(
        child: (Scaffold(
            body: StreamBuilder(
                stream: FirebaseFirestore.instance.collection('manuais').snapshots(),builder: (context,snapshot) {
                  if (snapshot.data == null) return CircularProgressIndicator();

                  return Container(
                    padding: EdgeInsets.all(16),child: ListView.builder(
                        itemCount: snapshot.data.documents.length,itemBuilder: (context,index) {
                          DocumentSnapshot manuais =
                          snapshot.data.documents[index];

                          final imgUrl = manuais.data()['documento'];

                          var dio = Dio();

                          return Card(
                            color: Colors.grey[250],child: Container(
                              padding: EdgeInsets.all(10),child: Column(
                                crossAxisAlignment: CrossAxisAlignment.start,children: <Widget>[

                                  Image.network(manuais.data()['logo'].toString(),width: 32,),Center(
                                    child: Text(
                                      (manuais.data()['nome'].toString()),maxLines: 1,overflow: TextOverflow.ellipsis,style: TextStyle(fontSize: 16),ButtonBar(
                                    children: <Widget>[



                                      //BOTAO DE DOWNLOAD
                                      FlatButton(
                                          child: const Text('Download'),onPressed:  () async {
                                            String path =
                                            await ExtStorage.getExternalStoragePublicDirectory(
                                              ExtStorage.DIRECTORY_DOWNLOADS);
                                            String fullPath = '$path/newtask1.pdf';
                                            download2(dio,imgUrl,fullPath);
                                        },FlatButton(
                                          child: const Text('Compartilhar'),onPressed: () async {
                                              if (snapshot.data == null) return CircularProgressIndicator();

                                              var request = await HttpClient().getUrl(Uri.parse(manuais.data()['documento']));
                                              var response = await request.close();Uint8List bytes = await consolidateHttpClientResponseBytes(response);
                                              await Share.file(
                                                  'ESYS AMLOG','Manual.pdf',bytes,'image/jpg');
                                            }),],);
                        }),);
                })))),//TAB DE PRODUCAO
    Center(
        child: (Scaffold(
            body: StreamBuilder(
                stream: FirebaseFirestore.instance.collection('producao').snapshots(),index) {
                          DocumentSnapshot producao =
                          snapshot.data.documents[index];

                          return Card(
                            color: Colors.grey[250],children: <Widget>[
                                  Center(
                                    child: Image.network(producao.data()['img'].toString(),width: 260,Text(
                                    (producao.data()['data'].toString()),style: TextStyle(fontSize: 22),Text(
                                    (producao.data()['detail'].toString()),ButtonBar(
                                    children: <Widget>[

                                      FlatButton(
                                          child: const Text('DETALHES'),onPressed: () {}),FlatButton(
                                          child: const Text('COMPARTILHAR'),onPressed: () async {
                                            if (snapshot.data == null) return CircularProgressIndicator();

                                            var request = await HttpClient().getUrl(Uri.parse(producao.data()['img']));
                                            var response = await request.close();Uint8List bytes = await consolidateHttpClientResponseBytes(response);
                                            await Share.file(
                                                'ESYS AMLOG','amlog.jpg','image/jpg');
                                          }),Center(child: Text('Documentos')),];

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('Área do Cliente')),body: tabs[_currentIndex],bottomNavigationBar: BottomNavigationBar(
        currentIndex: _currentIndex,type: BottomNavigationBarType.shifting,iconSize: 28,items: [
          BottomNavigationBarItem(
              icon: Icon(Icons.picture_as_pdf),title: Text('Manuais'),backgroundColor: Colors.indigo),BottomNavigationBarItem(
              icon: Icon(Icons.build),title: Text('Produção'),BottomNavigationBarItem(
            icon: Icon(Icons.folder),title: Text('Documentos'),backgroundColor: Colors.indigo,)
        ],onTap: (index) {
          setState(() {
            _currentIndex = index;
          });
        },);
  }
}

void initState(){
  getPermission();
}
void getPermission() async{
  print('getPermission');
  await PermissionHandler().requestPermissions([PermissionGroup.storage]);

}

Future download2(Dio dio,String url,String savePath) async {
  try{
    var showDownloadProgress;
    Response response = await dio.get(
      url,onReceiveProgress: showDownloadProgress,options: Options(
        responseType: ResponseType.bytes,followRedirects: false,validateStatus: (status) {
          return status < 500;
        }),);

    File file = File(savePath);
    var raf = file.openSync(mode: FileMode.write);
    raf.writeStringSync(response.data);
    await raf.close();
  } catch (e) {
    print('error is');
    print(e);

  }




}
```

解决方法

final taskId = await FlutterDownloader.enqueue(
  url: 'your download link',savedDir: 'directory/your/folder',showNotification: true,// show download progress in status bar (for Android)
  openFileFromNotification: true,// click on notification to open downloaded file (for Android)
);

,

因为您使用了我的包裹flutter_cached_pdfview

您不需要自己下载pdf文件

该软件包可以下载文件，对其进行缓存并查看

 PDF().cachedFromUrl('your download link'),