Question

我如何将字节数组（以 JSON 中的字符串形式发送）转换为 .csv 文件。

到目前为止我所做的是

将 JSON 接收转换为 unit8list

并使用 .csv 文件创建一个新文件并将内容写入 file.writeAsBytes(bytes)

我正在获取 .csv 文件，但数据是在单单元格中写入的（作为在收到的 JSON 响应中收到的字符串）

// response from json
DownloadResponse  value = DownloadResponse.fromJson(jsonDecode(response.body));

List<int> bytes = utf8.encode(value.object);
   Uint8List bytes8 = Uint8List.fromList(bytes);
   print("-------------- List<int> ------------");

   print(bytes);
   print("-------------- END List<int> ------------");

   print("\n\n-------------- List<Unit8> ------------");

   print(bytes8);

   print("\n\n-------------- END List<Unit8> ------------");

print("location supply!!");
   File file = new File('/storage/emulated/0/Download/${currentFile.fileName}');
   File filety = new File('/storage/emulated/0/Download/file2.csv');


   print("creating file");
   var file2 = await file.writeAsBytes(bytes);
   var file3 = await filety.writeAsBytes(bytes8);

   var parent = file2.parent;
   var parent2 = file2.parent;
   print("parant: $parent");
   print("parant2: $parent2");

main.dart

import 'dart:async';
import 'dart:convert';
import 'dart:io';
import 'dart:typed_data';
import 'package:ext_storage/ext_storage.dart';
import 'package:flutter/material.dart';
import 'package:path_provider/path_provider.dart';
import 'package:path/path.dart' as path;
import 'package:permission_handler/permission_handler.dart';

void main() {
 runApp(
   MaterialApp(
     title: 'Reading and Writing Files',
     home: MyApp(),
   ),
 );
}

class MyApp extends StatefulWidget {
 @override
 _AppState createState() => _AppState();
}

class _AppState extends State<MyApp> {
 String data;
 String byteStr = "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";

 Future<File> moveFile(File sourceFile, String newPath) async {
   try {
     /// prefer using rename as it is probably faster
     /// if same directory path
     return await sourceFile.rename(newPath);
   } catch (e) {
     /// if rename fails, copy the source file
     final newFile = await sourceFile.copy(newPath);
     return newFile;
   }
 }

 Future<String> get _localPath async {
   final directory = await getApplicationDocumentsDirectory();
   print(directory.path);
   return directory.path;
 }

 Future<String> dirpath() async {
   var path = await ExtStorage.getExternalStoragePublicDirectory(ExtStorage.DIRECTORY_DOWNLOADS);
   print("download: "+path);
   return path;
 }

 Future<File> get _localFile async {
   final path = await _localPath;
    final extpath = await dirpath();

   File src = File('$path/counter.txt');
   String desc = '$extpath/counter.txt';

   var status = await Permission.storage.status;
   if (!status.isGranted) {
     await Permission.storage.request();

     var file =  await moveFile(src,desc);
     print("file::: ${file.path}");
   }

   // Permission.storage.request();

   File('$extpath/counter.txt');

   return File('$path/counter.txt');
 }

 Future<String> readContent() async {
   try {
     final file = await _localFile;
     // Read the file
     String contents = await file.readAsString();
     // Returning the contents of the file
     return contents;
   } catch (e) {
     // If encountering an error, return
     return 'Error!';
   }
 }

 Future<File> writeContent() async {
   final file = await _localFile;
   // Write the file
   return file.writeAsString('Hello Folk');
 }

 @override
 void initState() {
   super.initState();
    askedPermission();
 }

 @override
 Widget build(BuildContext context) {
   return Scaffold(
     appBar: AppBar(title: Text('Reading and Writing data')),
     body: Center(

       child: Column(
         children: [
           Text(
             'Data read from a file: \n $data',
           ),
           SizedBox(height: 20,),
           FlatButton(onPressed: (){
             setState(()  {

                // write();
               writeCsv();

             });
           }, child: Text("write")),

         ],
       ))
   );
 }

 Future<void> askedPermission() async {
   var status = await Permission.storage.status;
   print("start Status $status");
   if (!status.isGranted) {
     await Permission.storage.request();
     status = await Permission.storage.status;

       if(status.isGranted){

         print("location supply!!");
         File file = new File('/storage/emulated/0/Download/file.text');
         print("creating file");
         var file2 = await file.writeAsString("dhddhhd");

         var parent = file2.parent;
         print("parant: $parent");

        /* writeContent();
         readContent().then((String value) {
           setState(() {
             data = value;
           });
         });*/
       }
       else{
         print("No Permission to write File !!");
       }

   }
   print("end Status $status");
 }

 Future<void> write() async {

   print("location supply!!");
   File file = new File('/storage/emulated/0/Download/file.text');
   print("creating file");
   var file2 = await file.writeAsString("dhddhhd");

   var parent = file2.parent;
   print("parant: $parent");
 }

 Future<void> writeCsv() async {

   List<int> bytes = utf8.encode(byteStr);
   Uint8List bytes8 = Uint8List.fromList(bytes);
   print("-------------- List<int> ------------");

   print(bytes);
   print("-------------- END List<int> ------------");

   print("\n\n-------------- List<Unit8> ------------");

   print(bytes8);

   print("\n\n-------------- END List<Unit8> ------------");

   print("location supply!!");
   File file = new File('/storage/emulated/0/Download/file.csv');
   File filety = new File('/storage/emulated/0/Download/file2.csv');

   print("creating file");
   var file2 = await file.writeAsBytes(bytes);
   var file3 = await filety.writeAsBytes(bytes8);

   var parent = file2.parent;
   print("parant: $parent");
 }
}

Answer 1

我可以通过使用 base64 解码来创建 CSV 文件。如果有人需要，请在此处留下答案。

var decode = base64.decode(JsonResponseString);
    var csvStr = utf8.decode(decode);
    print(csvStr.toString());

    print("creating file...");
    File file =
        new File('/storage/emulated/0/Download/${currentFile.fileName}.csv');

    file.writeAsString(csvStr);

如何在颤振中将字节数组转换为 .csv 文件

1 个答案: