java - Flutter stomp 客户端无法与 spring stomp 客户端连接

Question

我是 Flutter 新手。我正在尝试连接到使用 stomp 的 spring websocket，但连接失败。我正在使用 stomp_dart_client 0.3.3。 Spring服务器工作正常。我可以在浏览器上看到消息。

这是我的 spring 实现:

Spring 配置类:

@Override
public void configureMessageBroker(MessageBrokerRegistry config) {
    config.enableSimpleBroker("/topic");
    config.setApplicationDestinationPrefixes("/app");
}

@Override
public void registerStompEndpoints(StompEndpointRegistry registry) {
    registry.addEndpoint("/gs-guide-websocket").withSockJS();
}

Spring Controller :

@MessageMapping("/hello")
@SendTo("/topic/greetings")
public Greeting greeting(HelloMessage message) throws Exception {
    Thread.sleep(1000); // simulated delay
    return new Greeting("Hello, " + HtmlUtils.htmlEscape(message.getName()) + "!");
}

flutter 实现:

StompClient stompClient = StompClient(
        config: StompConfig(
          url: 'ws://10.0.2.2:7000',
          onConnect:(ss, dd)=> ss.subscribe (
            destination: '/topic/greetings/gs-guide-websocket',
            callback: (StompFrame frame) {
              print(frame.body);
            },
          ),
          onWebSocketError: (dynamic error) => print(error.toString()),
          onStompError: (d) => print("stomp error"),
          onDisconnect: (d)=> print("disconnect"),
        ));

   stompClient.activate();

   stompClient.subscribe (
        destination: '/topic/greetings',
        callback: (StompFrame frame) {
          print(frame.body);
          List<dynamic> result = json.decode(frame.body);
          return result;
        },
    );

这是错误:

E/flutter (30825): [ERROR:flutter/shell/common/shell.cc(213)] Dart Error: Unhandled exception:
E/flutter (30825): NoSuchMethodError: The method 'subscribe' was called on null.
E/flutter (30825): Receiver: null
E/flutter (30825): Tried calling: subscribe(callback: Closure: (StompFrame) => List<dynamic>, destination: "/topic/greetings", headers: null)
E/flutter (30825): #0      Object.noSuchMethod (dart:core-patch/object_patch.dart:53:5)
E/flutter (30825): #1      StompClient.subscribe (package:stomp_dart_client/stomp.dart:74:21)
E/flutter (30825): #2      _MyHomePageState._receivedMessage (package:tutorial_projecect/main.dart:154:16)
E/flutter (30825): #3      _MyHomePageState.build (package:tutorial_projecect/main.dart:90:41)
E/flutter (30825): #4      StatefulElement.build (package:flutter/src/widgets/framework.dart:4619:28)
E/flutter (30825): #5      ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:4502:15)
E/flutter (30825): #6      StatefulElement.performRebuild (package:flutter/src/widgets/framework.dart:4675:11)
E/flutter (30825): #7      Element.rebuild (package:flutter/src/widgets/framework.dart:4218:5)
E/flutter (30825): #8      StatefulElement.update (package:flutter/src/widgets/framework.dart:4707:5)
E/flutter (30825): #9      Element.updateChild (package:flutter/src/widgets/framework.dart:3201:15)
E/flutter (30825): #10     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:5837:14)
E/flutter (30825): #11     Element.updateChild (package:flutter/src/widgets/framework.dart:3201:15)
E/flutter (30825): #12     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:4527:16)
E/flutter (30825): #13     Element.rebuild (package:flutter/src/widgets/framework.dart:4218:5)
E/flutter (30825): #14     StatelessElement.update (package:flutter/src/widgets/framework.dart:4583:5)
E/flutter (30825): #15     Element.updateChild (package:flutter/src/widgets/framework.dart:3201:15)
E/flutter (30825): #16     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:5837:14)
E/flutter (30825): #17     Element.updateChild (package:flutter/src/widgets/framework.dart:3201:15)
E/flutter (30825): #18     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:5837:14)
E/flutter (30825): #19     Element.updateChild (package:flutter/src/widgets/framework.dart:3201:15)
E/flutter (30825): #20     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:4527:16)
E/flutter (30825): #21     StatefulElement.performRebuild (package:flutter/src/widgets/framework.dart:4675:11)
E/flutter (30825): #22     Element.rebuild (package:flutter/src/widgets/framework.dart:4218:5)
E/flutter (30825): #23     StatefulElement.update (package:flutter/src/widgets/framework.dart:4707:5)
E/flutter (30825): #24     Element.updateChild (package:flutter/src/widgets/framework.dart:3201:15)
E/flutter (30825): #25     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:5837:14)
E/flutter (30825): #26     Element.updateChild (package:flutter/src/widgets/framework.dart:3201:15)
E/flutter (30825): #27     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:5837:14)
E/flutter (30825): #28     Element.updateChild (package:flutter/src/widgets/framework.dart:3201:15)
E/flutter (30825): #29     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:4527:16)
E/flutter (30825): #30     StatefulElement.performRebuild (package:flutter/src/widgets/framework.dart:4675:11)
E/flutter (30825): #31     Element.rebuild (package:flutter/src/widgets/framework.dart:4218:5)
E/flutter (30825): #32     StatefulElement.update (package:flutter/src/widgets/framework.dart:4707:5)
E/flutter (30825): #33     Element.updateChild (package:flutter/src/widgets/framework.dart:3201:15)
E/flutter (30825): #34     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:4527:16)
E/flutter (30825): #35     Element.rebuild (package:flutter/src/widgets/framework.dart:4218:5)
E/flutter (30825): #36     StatelessElement.update (package:flutter/src/widgets/framework.dart:4583:5)
E/flutter (30825): #37     Element.updateChild (package:flutter/src/widgets/framework.dart:3201:15)
E/flutter (30825): #38     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:4527:16)
E/flutter (30825): #39     StatefulElement.performRebuild (package:flutter/src/widgets/framework.dart:4675:11)
E/flutter (30825): #40     Element.rebuild (package:flutter/src/widgets/framework.dart:4218:5)
E/flutter (30825): #41     StatefulElement.update (package:flutter/src/widgets/framework.dart:4707:5)
E/flutter (30825): #42     Element.updateChild (package:flutter/src/widgets/framework.dart:3201:15)
E/flutter (30825): #43     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:5837:14)
E/flutter (30825): #44     Element.updateCh

Answer 1

将其拉回到提到 stomp_dart_client 的原始帖子，我努力在互联网和 Stack Overflow 上找到这方面的工作示例，所以这是我的解决方案，可能会有所帮助。

我正在使用带有 Web STOMP 插件的 RabbitMQ:https://www.rabbitmq.com/web-stomp.html ，将 JSON 数据包发布到名为“ping”的队列上。 stomp_dart_client 的示例和文档不清楚如何连接到安全 session ，我通过在 header 中添加身份验证来解决这个问题:

import 'dart:convert';

import 'package:stomp_dart_client/stomp.dart';
import 'package:stomp_dart_client/stomp_config.dart';
import 'package:stomp_dart_client/stomp_frame.dart';

dynamic onConnect(StompClient client, StompFrame frame) {
  client.subscribe(
      destination: 'ping',
      callback: (StompFrame frame) {
        var jsonData = json.decode(frame.body);
        print(jsonData);
      });
}

final stompClient = StompClient(
    config: StompConfig(
        url: 'ws://x.x.x.x:15674/ws',
        onConnect: onConnect,
        onWebSocketError: (dynamic error) => print(error.toString()),
        stompConnectHeaders: {
      'login': 'someuserlogin',
      'passcode': 'somepassword'
    },
));

void main() {
  stompClient.activate();
}