安装应用程序时创建文件夹

Question

如何在设备存储中创建文件夹以保存文件？

这是将文件下载到设备中的代码：

import 'package:flutter_downloader/flutter_downloader.dart';

onTap: () async { //ListTile attribute
   Directory appDocDir = await getApplicationDocumentsDirectory();                
   String appDocPath = appDocDir.path;
   final taskId = await FlutterDownloader.enqueue(
     url: 'http://myapp/${attach[index]}',
     savedDir: '/sdcard/myapp',
     showNotification: true, // show download progress in status bar (for Android)
     clickToOpenDownloadedFile: true, // click on notification to open downloaded file (for Android)
   );
},

Answer 1

从我看到的结果来看，您没有在任何地方使用appDocDir和appDocPath，因为您将文件保存在/sdcard/myapp中。

请检查您是否在询问并授予存储许可，并且也无法像您一样将文件存储在sdcard中。可以使用预定义目录（例如，文档，图片等），也可以使用以storage/emulated/0

开头的设备根目录。

Answer 2

您可以在启动应用程序时创建目录。 在第一个屏幕的initState()方法中，执行逻辑。

例如。

createDir() async {
  Directory baseDir = await getExternalStorageDirectory(); //only for Android
  // Directory baseDir = await getApplicationDocumentsDirectory(); //works for both iOS and Android
  String dirToBeCreated = "<your_dir_name>";
  String finalDir = join(baseDir, dirToBeCreated);
  var dir = Directory(finalDir);
  bool dirExists = await dir.exists();
  if(!dirExists){
     dir.create(/*recursive=true*/); //pass recursive as true if directory is recursive
  }
  //Now you can use this directory for saving file, etc.
  //In case you are using external storage, make sure you have storage permissions.
}

@override
initState(){
  createDir(); //call your method here
  super.initState();
}

您需要导入以下库：

import 'dart:io';
import 'package:path/path.dart';
import 'package:path_provider/path_provider.dart';

Answer 3

var A = {
  hello : function() {
    console.log('hello');
  }
}
var B = {}
B.prototype = A;
var C = {}
C.prototype = B;
C.hello();

Answer 4

这是在用户内部存储中创建文件夹的示例代码，希望它对您有帮助

import 'dart:io' as Io;



Future _downloadImage() async {
try {
    // request runtime permission
    final permissionHandler = PermissionHandler();
    final status = await permissionHandler
        .checkPermissionStatus(PermissionGroup.storage);
    if (status != PermissionStatus.granted) {
      final requestRes = await permissionHandler
          .requestPermissions([PermissionGroup.storage]);
      if (requestRes[PermissionGroup.storage] != PermissionStatus.granted) {
        _showSnackBar('Permission denined. Go to setting to granted!');
        return _done();
      }
    }
  }
  var testdir =
  await new Io.Directory('/storage/emulated/0/MyApp').create(recursive: true);
  final filePath =
      path.join(testdir.path, Filename + '.png');
  print(filePath);
  final file = File(filePath);
  if (file.existsSync()) {
    file.deleteSync();
  }
 //save image to storage
  var request = await HttpClient().getUrl(Uri.parse(imageUrl));
  var response = await request.close();
  final Uint8List bytes = await consolidateHttpClientResponseBytes(response);
  final saveFileResult =
      saveImage({'filePath': filePath, 'bytes': bytes});
 _showSnackBar(
    saveFileResult
        ? 'Image downloaded successfully'
        : 'Failed to download image',
  );
} on PlatformException catch (e) {
  _showSnackBar(e.message);
} catch (e, s) {
  _showSnackBar('An error occurred');
  debugPrint('Download image: $e, $s');
}
return _done();
 }

Answer 5

首先您需要导入

1）导入'dart：io';

第二步，您需要在异步/等待功能中为指定路径创建目录

2）例如： 等待新目录（'/storage/emulated/0/yourFolder').create(recursive：true）;