使用RefreshIndicator用后端的新数据重建小部件UI？

Question

我目前正在尝试使用“拉动刷新”在Flutter中实现刷新功能。 “拉动刷新”将要做的是从后端检索任何新任务，并使用它来更新UI。虽然我可以使用onRefresh字段来使用REST API（方法为fetchTasks）来获取更新的任务，但是我不确定如何更新/重建UI来显示此信息。新任务。特别是，如何在不更改buildListViewWidget方法中看到的FutureBuilder的使用的情况下实现这一目标。任何帮助将不胜感激！代码的关键部分如下所示

main.dart

final GlobalKey<RefreshIndicatorState> _refreshIndicatorKey =
      new GlobalKey<RefreshIndicatorState>();

  Future<Null> refreshList() {}

  @override
  Widget build(BuildContext context) {
    // Widget that holds the title section
    return MaterialApp(
        title: 'learning',
        home: Scaffold(
            appBar: AppBar(
              title: Text('Todo list'),
            ),
            body: RefreshIndicator(
                key: _refreshIndicatorKey,
                onRefresh: fetchTask,
                child: ListView(
                  children: [
                    Image.asset(
                      'images/lake.jpg',
                      width: 600.0,
                      height: 240.0,
                      fit: BoxFit.cover,
                    ),
                    buildListViewWidget(),
                    Row(
                        mainAxisAlignment: MainAxisAlignment.spaceEvenly,
                        children: <Widget>[
                          Flexible(
                              child: Padding(
                                  padding: const EdgeInsets.fromLTRB(
                                      32.0, 0.0, 0.0, 16.0),
                                  child: TextField(
                                    controller: myController,
                                    decoration: InputDecoration(
                                      border: InputBorder.none,
                                      hintText: 'Please enter a todo task',
                                    ),
                                  ))),
                          Padding(
                              padding: const EdgeInsets.fromLTRB(
                                  0.0, 0.0, 32.0, 16.0),
                              child: RaisedButton(
                                child: const Text('Submit'),
                                color: Colors.red,
                                highlightColor: Colors.blue,
                                elevation: 4.0,
                                onPressed: () {
                                  String temp = myController.text;
                                  myController.clear();
                                  Map map = {'task': temp};
                                  apiRequest(post_url, map);
                                },
                              ))
                        ]),
                  ],
                )
            )
        )
    );
  }

  FutureBuilder<List<Task>> buildListViewWidget() {
    return new FutureBuilder<List<Task>>(
        future: fetchTask(),
        builder: (context, snapshot) {
          if (snapshot.hasData) {
            print("Data is present");
            return new ListGenerator(todoList: snapshot.data);
          } else if (snapshot.hasError) {
            return Text("${snapshot.error}");
          }

          // By default, show a loading spinner
          return Center(child: CircularProgressIndicator());
        });
  }

list_generator.dart

import 'package:flutter/material.dart';
import 'task.dart';

class ListGenerator extends StatefulWidget {
  final List<Task> todoList;

  ListGenerator({Key key, this.todoList}) : super(key: key);

  @override
  _ListGeneratorState createState() => _ListGeneratorState();
}

class _ListGeneratorState extends State<ListGenerator> {

  final _biggerFont = const TextStyle(fontSize: 18.0);

  Widget build(BuildContext context) {

    Widget _buildTodoList() {
      return ListView.separated(
          physics: const ScrollPhysics(),
          itemCount: widget.todoList == null ? 0 : widget.todoList.length,
          separatorBuilder: (BuildContext, int index) => Divider(),
          shrinkWrap: true,
          padding: const EdgeInsets.all(32.0),
          itemBuilder: (context, i) {
            return ListTile(
              title: Text(
                  widget.todoList[i].getTask(),
                  style: _biggerFont
              ),
              trailing: new Icon(
                  Icons.delete,
                  color: Colors.grey
              ),
            );
          }
      );
    }

    return _buildTodoList();
  }

}

task_methods.dart

import 'task.dart';
import 'package:http/http.dart' as http;
import 'package:flutter/foundation.dart';
import 'dart:convert';
import 'package:flutter/material.dart';
import 'list_generator.dart';

Future<List<Task>> fetchTask() async {
  final response =
  await http.get(BACKEND_URL);

  if (response.statusCode == 200) {
    print(response.body);
    // If the call to the server was successful, parse the JSON
    return compute(parseData, response.body);
  } else {
    // If that call was not successful, throw an error.
    throw Exception('Failed to load post');
  }
}

List<Task> parseData(String response) {
  final parsed = json.decode(response);

  return (parsed["data"] as List).map<Task>((json) =>
  new Task.fromJson(json)).toList();
}