线性进度指标在下载文件时无法管理其状态

Question

我是Flutter的新手，目前正在开发一个从给定链接下载文件的Flutter应用程序。问题是，当只有一个链接应用程序正常运行时，但是当一个以上的链接到达文件未下载时。我在JSON文件中接收链接数据，然后解析JSON并在ListView.builder中使用这些链接。我尝试了很多，但找不到解决方案。这是屏幕的代码。主要问题是我认为状态不能很好地管理。

dsharing.json文件包含文件的名称和链接

import 'dart:convert';
import 'package:dio/dio.dart';
import 'package:flutter/material.dart';
import 'package:http/http.dart';
import '../services/services.dart';

class ReceiveScreen extends StatefulWidget {
 const ReceiveScreen({Key? key, }) : super(key: key);

@override
State<ReceiveScreen> createState() => _ReceiveScreenState();
 }

 class _ReceiveScreenState extends State<ReceiveScreen> {

 Map<int, double> progress = {};
 int received = 0;
 int total = 0;
 var _url = "http://192.168.1.100:50500";

 List<Receiver> receivers = [];
 @override
 initState()
 {
   super.initState();

 }

 @override
 void dispose() {
  super.dispose();
 }


@override
Widget build(BuildContext context) {
  return Scaffold(
  appBar: AppBar(
    title: const Text("Receive Files"),
  ) ,
    body: Column(
      children: [

        ElevatedButton(
            onPressed: ()async
            {
              await getUrls();
            },
            child: const Text("Get Response")
        ),

        Text(rsponse),
        FutureBuilder(
          future: getUrls(),
            builder: (context, AsyncSnapshot<Files>  snapshot)
                {
                  if(!snapshot.hasData)
                    {
                      return const Center(child:  CircularProgressIndicator());
                    }
                    Files files = snapshot.data!;
                  return ListView.builder(
                    itemCount: files.names!.length,
                    shrinkWrap: true,
                      itemBuilder: (context, index)
                      {
                        
                        return Column(
                        children: [
                          ElevatedButton(
                              onPressed: () async
                              {
                                final path = "/storage/emulated/0/Download/${files.names![index]}";
                                await Dio().download(
                                    files.urls![index],
                                    path,
                                    onReceiveProgress: (received, total)
                                    {
                                      progress[index] = received/total;
                                    }
                                );
                              },
                              child: Text("${files.names![index] } Download")
                          ),
                          LinearProgressIndicator(
                            value: progress[index],
                            minHeight: 20,
                          )
                        ],
                        );
                      }
                  );
                }
        )

     
      ],
    )
);
 }
 String rsponse = "";
 fetchDataApi() async
 {
   var response = await get(Uri.parse("$_url/dsharing.json"));

   if(response.statusCode == 200)
    {
     return jsonDecode(response.body);
    }
   }

 Future<Files> getUrls() async
 {
   var data = await fetchDataApi();
    return Files.fromJson(data, _url);
  }



  }



class Files
{
  final List? names;
  final List? urls;

  Files({ this.names, this.urls});

  factory Files.fromJson(Map map, String url)
  {
   var fileNames = [];
   String name = map['name'];
   if(name.contains(":"))
    {
     int index = name.indexOf(":") + 1;
     name = name.substring(index + 1, name.length);
     var x = name.replaceAll(" ", '^*&');
     fileNames = x.split("^*&").toList();
    }
   else
     {
      fileNames.add(name);
     }
     var x = map['data'].toString().split("|dsharing|").toList();
     var fileUrls = x.map((i) => url + "?/q="+ i).toList();
      return Files(
      names: fileNames,
      urls: fileUrls
    );
   }


 }