Question

我有一个需要拉动刷新功能的应用程序，因此我将 StreamBuilder窗口小部件放置在 RefreshIndicator窗口小部件中，但是我不知道如何手动刷新触发 onRefreshed 事件时，将其添加到StreamBuilder。

Answer 1

将stream作为state variable并在上拉刷新时重置将解决此问题。

在下面的代码中，我将在按下按钮时重置流。希望对您有帮助。

import 'dart:async';

import 'package:flutter/material.dart';

void main() => runApp(new MyApp());

class MyApp extends StatefulWidget {
  @override
  State<StatefulWidget> createState() {
    return new _MyAppState();
  }
}

class _MyAppState extends State<MyApp> {
  var stream; // state variable

  @override
  void initState() {
    super.initState();
    stream = newStream(); // initial stream
  }

  Stream<String> newStream() =>
      Stream.periodic(Duration(seconds: 1), (i) => "$i");

  @override
  Widget build(BuildContext context) {
    var streamBuilder = StreamBuilder(
        initialData: "0",
        stream: stream,
        builder: (context, snapshot) {
          return new Text(snapshot.data);
        });
    return MaterialApp(
        title: 'Trial',
        home: Scaffold(
            appBar: AppBar(title: Text('Stream builder')),
            body: Column(
              children: <Widget>[
                streamBuilder,
                FlatButton(
                    onPressed: () {
                      setState(() {
                        stream = newStream(); //refresh/reset the stream
                      });
                    },
                    child: Text("Reset"))
              ],
            )));
  }
}

Answer 2

可以使用RefreshIndicatorState。show方法轻松完成此操作：

class _MyAppState extends State<MyApp> {
  final refreshIndicatorKey = GlobalKey<RefreshIndicatorState>();

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Trial',
      home: Scaffold(
        appBar: AppBar(title: Text('Stream builder')),
        body: Column(
          children: <Widget>[
            StreamBuilder(
              stream: <stream>, // Stream is here
              builder: (context, snapshot) {
                return 
                  RefreshIndicator(
                    key: refreshIndicatorKey,     // Specify a key declared above!
                    onRefresh() => <future>       // Refresh callback is here
                    child: ListView.builder(...), // List view is built here
                  );
              },
            ),
            FlatButton(
              child: Text('Reload'),
              onPressed: () {
                // Show refresh indicator and run refresh callback
                refreshIndicatorKey.currentState.show(); 
              }
            ),
          ],
        ),
      );
    }
  }
}

如何手动刷新或重新加载Flutter Firestore StreamBuilder？

2 个答案: