Flutter：如何把ssh变成树莓派

Question

So I'm trying to do a very simple thing (in theory). I want to communicate with my Raspberry Pi and I want to make it into an app. I was looking at flutter packages and there's one that allows you to ssh. So I thought I'd just ssh into my Pi and run a script but I get an error which I have no idea what it means. Thanks for the help in advance: Here's my code and the error:

import 'dart:async';
import 'package:flutter/services.dart';
import 'package:flutter/material.dart';
import 'package:ssh/ssh.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Lights',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        children: <Widget>[
          Center(
            child: RaisedButton(
              onPressed: lightsOff,
              child: Text("Lights Off"),
            ),
          ),
        ],
      ),
    );
  }

  Future<void> lightsOff() async {
    final pi = new SSHClient(
      host: "IP_ADDRESS",
      port: 22,
      username: "pi",
      passwordOrKey: "raspberry",
    );

    String result;
    try {
      result = await pi.connect();
      if (result == "session_connected")
        result = await pi.execute("sudo python /home/pi/Desktop/scripts/lightOff.py");
    } on PlatformException catch (e) {
      print('Error: ${e.code}\nError Message: ${e.message}');
    }
  }
}

Error:

flutter: ══╡ EXCEPTION CAUGHT BY SERVICES LIBRARY ╞══════════════════════════════════════════════════════════
flutter: The following MissingPluginException was thrown while activating platform stream on channel
flutter: shell_sftp:
flutter: MissingPluginException(No implementation found for method listen on channel shell_sftp)
flutter:
flutter: When the exception was thrown, this was the stack:
flutter: #0      MethodChannel.invokeMethod (package:flutter/src/services/platform_channel.dart:291:7)
flutter: <asynchronous suspension>
flutter: #1      EventChannel.receiveBroadcastStream.<anonymous closure> (package:flutter/src/services/platform_channel.dart:437:29)
flutter: <asynchronous suspension>
flutter: #9      new SSHClient (package:ssh/ssh.dart:40:40)
flutter: #10     _MyHomePageState.lightsOff (package:lights/main.dart:48:20)
flutter: <asynchronous suspension>
flutter: #11     _InkResponseState._handleTap (package:flutter/src/material/ink_well.dart:507:14)
flutter: #12     _InkResponseState.build.<anonymous closure> (package:flutter/src/material/ink_well.dart:562:30)
flutter: #13     GestureRecognizer.invokeCallback (package:flutter/src/gestures/recognizer.dart:102:24)
flutter: #14     TapGestureRecognizer._checkUp (package:flutter/src/gestures/tap.dart:242:9)
flutter: #15     TapGestureRecognizer.handlePrimaryPointer (package:flutter/src/gestures/tap.dart:175:7)
flutter: #16     PrimaryPointerGestureRecognizer.handleEvent (package:flutter/src/gestures/recognizer.dart:315:9)
flutter: #17     PointerRouter._dispatch (package:flutter/src/gestures/pointer_router.dart:73:12)
flutter: #18     PointerRouter.route (package:flutter/src/gestures/pointer_router.dart:101:11)
flutter: #19     _WidgetsFlutterBinding&BindingBase&GestureBinding.handleEvent (package:flutter/src/gestures/binding.dart:180:19)
flutter: #20     _WidgetsFlutterBinding&BindingBase&GestureBinding.dispatchEvent (package:flutter/src/gestures/binding.dart:158:22)
flutter: #21     _WidgetsFlutterBinding&BindingBase&GestureBinding._handlePointerEvent (package:flutter/src/gestures/binding.dart:138:7)
flutter: #22     _WidgetsFlutterBinding&BindingBase&GestureBinding._flushPointerEventQueue (package:flutter/src/gestures/binding.dart:101:7)
flutter: #23     _WidgetsFlutterBinding&BindingBase&GestureBinding._handlePointerDataPacket (package:flutter/src/gestures/binding.dart:85:7)
flutter: #24     _invoke1 (dart:ui/hooks.dart:168:13)
flutter: #25     _dispatchPointerDataPacket (dart:ui/hooks.dart:122:5)
flutter: (elided 7 frames from package dart:async)
flutter: ════════════════════════════════════════════════════════════════════════════════════════════════════
[VERBOSE-2:shell.cc(184)] Dart Error: Unhandled exception:
MissingPluginException(No implementation found for method connectToHost on channel ssh)
#0      MethodChannel.invokeMethod (package:flutter/src/services/platform_channel.dart:291:7)
<asynchronous suspension>
#1      SSHClient.connect (package:ssh/ssh.dart:63:33)
<asynchronous suspension>
#2      _MyHomePageState.lightsOff (package:lights/main.dart:57:25)
#3      _AsyncAwaitCompleter.start (dart:async/runtime/libasync_patch.dart:49:6)
#4      _MyHomePageState.lightsOff (package:lights/main.dart:47:25)
#5      _InkResponseState._handleTap (package:flutter/src/material/ink_well.dart:507:14)
#6      _InkResponseState.build.<anonymous closure> (package:flutter/src/material/ink_well.dart:562:30)
#7      GestureRecognizer.invokeCallback (package:flutter/src/gestures/recognizer.dart:102:24)
#8      TapGestureRecognizer._checkUp (package:flutter/src/gestures/tap.dart:242:9)
#9      TapGestureRecognizer.handlePrimaryPointer (package:flutter/src/gesture<…>

Answer 1

The exception is thrown when you try to Hot Reload or Hot Restart after just adding new package to your pubspec.yaml.

Try to stop the running project(app) and then freshly run it again. So that the added package(which contains the implementations) also pushed to the device.