Question

是否有一个StreamBuilder允许我收听多个流？像这样：

   body: MultiStreamBuilder(
        streams: [bloc.state.stream, bloc.kind.stream],
        builder: (context) {

我不需要Flutter StreamBuilder中的快照，因为我可以从团体中读取

Answer 1

只要其中一个流得到更新，这就会更新UI（调用构建）。我不使用snapshot.data，因为我直接从bloc读取数据，并且snapshot.data仅包含布尔值，而不包含流的实际数据。

class _RemoteDebuggingScreenState extends State<RemoteDebuggingScreen> {
  @override
  Widget build(BuildContext context) {
    RemoteDebugBlog bloc = BlocProvider.of(context).remoteDebugBloc;

    return Scaffold(
      body: StreamBuilder(
        stream: Observable.combineLatest2(bloc.state.stream, bloc.kind.stream,
            (b1, b2) => b1 != null || b2 != null),
        builder: (context, snapshot) {
          if (!snapshot.hasData) return Container();

          return Column(...

有关combineLatest的一些精美图片的更多信息，请查看以下内容： https://www.burkharts.net/apps/blog/rxdart-magical-transformations-of-streams/

现在了解了以上内容，我将其移至了一个小部件中：

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

class DoubleStreamBuilder extends StatelessWidget {
  @override
  DoubleStreamBuilder(
      {@required this.stream1, @required this.stream2, @required this.builder});

  final Stream stream1;
  final Stream stream2;
  final Widget Function(BuildContext) builder;

  Widget build(BuildContext context) => StreamBuilder(
      stream: Observable.combineLatest2(
          stream1, stream2, (b1, b2) => b1 != null || b2 != null),
      builder: (context, snapshot) => builder(context));
}

Answer 2

是的。

https://pub.dev/packages/multiple_stream_builder

// Pass multiple streams into a single StreamBuilder
Widget build(BuildContext context) {
  return StreamBuilder3<int, int, int>(
    streams: Tuple3(stream1, stream2, stream3),
    initialData: Tuple3(0, 0, 0),
    builder: (context, snapshots) {
      return Text(
        'stream1: ${snapshots.item1.data} - stream2: ${snapshots.item2.data} - stream3: ${snapshots.item3.data}',
      );
    },
  );
}

是否有Flutter StreamBuilder可以让我收听多个流？

2 个答案: