Flutter Dio 包下载路径

Question

My main goal is to download a file from a link and then save it to the phone's internal storage so that it'll be accessible through the phone's file manager. I'm currently trying out Dio package by running the example code given in the package's repo. Upon running the program, I ran into a path problem. When I used ./example/flutter.png as the download path, I/flutter (10109): FileSystemException: Cannot open file, path = './example/flutter.png' (OS Error: No such file or directory, errno = 2) shows up. And when I used (await getApplicationDocumentsDirectory()).path which produces a String with the value of: /data/user/0/com.example.downloadexample/app_flutter as the path, no error showed up, but the file wasn't there. I tried different variation of the latter path, but with no success. Can someone help me with this problem?

Many thanks in advance.

Answer 1

I use http package, not the Dio, the code:

Future<String> fetchNetFileToDoc(String url, String filename) async {
  final path = await getApplicationDocumentsDirectory();
  File docFile = File('$path/$filename');
    if(await docFile.exists()){
    print( '${docFile.path} exits');
    return docFile.path;
  }

  http.Response response = await http.get(url);
  // todo - check status
  await docFile.writeAsBytes(response.bodyBytes, flush: true);
  return docFile.path;
}

if I invoke this method, like: fetchNetFileToDoc('http://a.com/a.mp3', 'a.mp3') it shows the same error:

FileSystemException: Cannot open file, path= 'Direcotry: '/data/user/0/com.example.master_lu/app_flutter'/a.mp3' (OS Error: No such file or directory, errno = 2)

But if I use getTemporaryDirectory(), change code to this:

Future<String> fetchNetFileToTemp(String url, String filename) async {
  Directory tempDir = await getTemporaryDirectory();
  String tempPath = tempDir.path;
  File tempFile = File('$tempPath/$filename');
  if(await tempFile.exists()){
    print( '${tempFile.path} exits');
    return tempFile.path;
  }

  http.Response response = await http.get(url);
  // todo - check status
  await tempFile.writeAsBytes(response.bodyBytes, flush: true);
  return tempFile.path;
}

That's ok, it works with the internal storage. Save the file into the data/user/0/com.example.master_lu/cache/a.mp3 The master_lu is the name of my project.

The latest=> I sovle my problem, await getApplicationDocumentsDirectory return Future<Directory>

so, here is the right code:

Future<String> fetchNetFileToDoc(String url, String filename) async {
  final docDir = await getApplicationDocumentsDirectory();
  String docPath = docDir.path;
  File docFile = File('$docPath/$filename');
    if(await docFile.exists()){
    print( '${docFile.path} exits');
    return docFile.path;
  }

  http.Response response = await http.get(url);
  // todo - check status
  await docFile.writeAsBytes(response.bodyBytes, flush: true);
  return docFile.path;
}