在ConnectionState.done之后使用多个流重新启动StreamBuilder [英] Restart StreamBuilder with multiple streams after ConnectionState.done

问题描述

当您要在StreamBuilder中使用多个流时，重新启动StreamBuilder以使用下一个流时，有什么好方法？

What's a good way when you want to use multiple streams in a StreamBuilder, to restart StreamBuilder to use the next stream?

现在，我正在通过在标志（_streamCompleted）上使用setState检查流是否已完成。

Right now, I am checking if the stream is completed by using setState on a flag (_streamCompleted).

但是我想知道在ConnectionState.done被触发后是否可以重用StreamBuilder。

But I was wondering if it's possible to reuse the StreamBuilder after ConnectionState.done is fired.

 Stream donwloadStream = response.stream.map(processDownload);

...

StreamBuilder(
    stream: _streamIndex == null ? null : streams[_streamIndex].stream,
    builder: (context, snapshot) {

      if (ConnectionState.done) {
        // How do I switch to the next stream here ???
      }

这是我检查是否完成的方式：

This is how I am checking if completed:

double processDownload(List<int> chunk) {
    bytes.addAll(chunk);
    cnt = bytes.length;
    double progress = cnt / streams[_streamIndex].contentLength;

    if (cnt / streams[_streamIndex].contentLength == 1) {
      setState(() {           
          _streamCompleted = true;
          _streamIndex++;
      });
    }
     return progress;
 }

我也尝试过使用CombineLatestStream，但无法获取流要开始触发，ConnectionState为空。

I have also tried using CombineLatestStream, but couldn't get the streams to start firing, ConnectionState is none.

StreamBuilder(
            stream: _combinedStreams == null ? null : _combinedStreams,

    setState(() {
      _combinedStreams =
          CombineLatestStream.list([streams[0].stream, streams[1].stream, streams[2].stream])
              .asBroadcastStream();
    });

  _combinedStreams.listen((event) {});

推荐答案

只需使用两个流生成器。

Just use two stream builder.

StreamBuilder(
    stream: _streamIndex == null ? null : streams[_streamIndex].stream,
    builder: (context, snapshot) {
      if (ConnectionState.done) {
        StreamBuilder(
            stream: _stream2 == null ? null : streams2.stream,
            builder: (context, snapshot2) {...

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