Flutter:访问流程标准输出和流到StreamBuilder小部件

Question

我希望能够使用await Process.start()启动一个进程，并能够在进程执行期间访问标准输出，并将输出发送到StreamBuilder小部件。

StreamBuilder小部件

StreamBuilder(
stream: snapshot.data,
builder: (BuildContext context, AsyncSnapshot stream) {
print('Connection State: ${stream.connectionState}');
switch (stream.connectionState) {
case ConnectionState.done:
return SingleChildScrollView(
controller: controller,
reverse: true,
child: Text(
executionOutput,
));
default:
executionOutput += 'n${stream.data}';
return SingleChildScrollView(
controller: controller,
reverse: true,
child: Text(
executionOutput,
));

这是我的流代码，我想检查每秒钟的标准输出，直到进程结束

Stream getOutput() async* {
var p = await Process.start('python.exe', ['streamData.py']);
while (true) {
await Future.delayed(Duration(seconds: 1));
yield p.stdout.transform(utf8.decoder).toString();
}
}

Answer 1

使用yield*将流委托给另一个流

import 'dart:convert';
import 'dart:io';
void main(List<String> args) {
getOutput().listen(print);
}
Stream getOutput() async* {
var p = await Process.start('tail', ['-f', '/path/to/log']);
yield* p.stdout.transform(utf8.decoder);
}