在Flutter中下载文件

Question

我正在制作一个Flutter应用程序，首先我展示了有关PDF文件的所有信息，并包括来自Restful API的文件URL。一切都运转良好，但当用户单击它时，我想下载此文件。我尝试了以下方法：

 onTap: () async {
                                // downloadFile(snapshot.data[index].file);
                                Dio dio = new Dio();
                                Directory dir =
                                    await getApplicationDocumentsDirectory();
                                String path = dir.path;
                                await dio.download(
                                    snapshot.data[index].file, path);
                              },

snapshot.data[index].file，path是来自API的正确路径或文件，但它无法正常工作，并在此代码中给出了一个错误（path）。

await getApplicationDocumentsDirectory();
String path = dir.path;

this is my error log:

E/flutter (26482): [ERROR:flutter/shell/common/shell.cc(188)] Dart Error: Unhandled exception:
E/flutter (26482): FileSystemException: Cannot open file, path = '/data/data/com.example.mis/app_flutter' (OS Error: Is a
directory, errno = 21)
E/flutter (26482): #0      _File.throwIfError (dart:io/file_impl.dart:647:7)
E/flutter (26482): #1      _File.openSync (dart:io/file_impl.dart:491:5)
E/flutter (26482): #2      Dio.download (package:dio/src/dio.dart:212:20)
E/flutter (26482): <asynchronous suspension>
E/flutter (26482): #3      MaterialsState.build.<anonymous closure>.<anonymous closure>.<anonymous closure>
(package:mis/courses/materials.dart:121:47)
E/flutter (26482): <asynchronous suspension>
E/flutter (26482): #4      _InkResponseState._handleTap (package:flutter/src/material/ink_well.dart:507:14)
E/flutter (26482): #5      _InkResponseState.build.<anonymous closure> (package:flutter/src/material/ink_well.dart:562:30)
E/flutter (26482): #6      GestureRecognizer.invokeCallback (package:flutter/src/gestures/recognizer.dart:102:24)
E/flutter (26482): #7      TapGestureRecognizer._checkUp (package:flutter/src/gestures/tap.dart:242:9)
E/flutter (26482): #8      TapGestureRecognizer.acceptGesture (package:flutter/src/gestures/tap.dart:204:7)
E/flutter (26482): #9      GestureArenaManager.sweep (package:flutter/src/gestures/arena.dart:156:27)
E/flutter (26482): #10     _WidgetsFlutterBinding&BindingBase&GestureBinding.handleEvent
(package:flutter/src/gestures/binding.dart:184:20)
E/flutter (26482): #11     _WidgetsFlutterBinding&BindingBase&GestureBinding.dispatchEvent
(package:flutter/src/gestures/binding.dart:158:22)
E/flutter (26482): #12     _WidgetsFlutterBinding&BindingBase&GestureBinding._handlePointerEvent
(package:flutter/src/gestures/binding.dart:138:7)
E/flutter (26482): #13     _WidgetsFlutterBinding&BindingBase&GestureBinding._flushPointerEventQueue
(package:flutter/src/gestures/binding.dart:101:7)
E/flutter (26482): #14     _WidgetsFlutterBinding&BindingBase&GestureBinding._handlePointerDataPacket
(package:flutter/src/gestures/binding.dart:85:7)
E/flutter (26482): #15     _invoke1 (dart:ui/hooks.dart:159:13)
E/flutter (26482): #16     _dispatchPointerDataPacket (dart:ui/hooks.dart:113:5)

有没有其他下载文件的方法？或者仅仅是打开它？非常感谢。

- Osama Mohammed

---

请发布错误日志。是的，还有另一种方法，您可以使用[flutter_downloader]插件，该插件专门用于创建和管理下载任务。支持iOS和Android。 https://pub.dartlang.org/packages/flutter_downloader - a0x2

谢谢，我会尝试，我会在帖子中添加错误。 - Osama Mohammed

https://dev59.com/bVMH5IYBdhLWcg3w1j71#57997334 - Amit Prajapati

Answer 1

万一其他人需要，这里提供解决方法。
问题在于你没有将文件路径作为参数传递，而是传递了一个目录。

await dio.download(snapshot.data[index].file, path+'/fileName.pdf');  

那应该解决问题了。

- nonybrighto

Answer 2

在Flutter中使用文件支持插件https://pub.dev/packages/file_support

Future<File> downloadFile async{
File file =await FileSupport(url:"http://test.com/.mp4");
 return file;
}

- Parmeet Singh

Answer 3

你可以使用这个包 flutter cache manager。

使用以下代码获取文件：

 String url = 'https://fileUrl';
File file = await DefaultCacheManager().getSingleFile(url);

然后您可以使用 'file' 来做您想做的事情。

- Ahmed El Rhaouti