Flutter Web 和移动端基于 MQTT 证书的身份验证答案

【问题标题】：MQTT certificate-based authentication in flutter web and mobileFlutter Web 和移动端基于 MQTT 证书的身份验证
【发布时间】：2020-04-28 19:28:57
【问题描述】：

我正在尝试在 Flutter 项目中使用 MQTT 来测试原型。我正在使用自定义的基于证书的身份验证。

我正在使用mqtt_client 包。在连接 SecurityContext 之前在网络中给出此错误 不支持的操作：默认 SecurityContext getter

下面是我的示例代码

  try {
      SecurityContext securityContext =
          SecurityContext(withTrustedRoots: false);
      securityContext.setTrustedCertificatesBytes(caCertificate);
      securityContext.useCertificateChainBytes(caCertificate);
      securityContext.setClientAuthoritiesBytes(clientCertificate,
          password: String.fromCharCodes(privateKey));
    } catch (e) {
      print(e);
    }

    _client = MqttClient('m.test.com', _identifier);
    _client.port = 8883;
    _client.keepAlivePeriod = 20;
    _client.onDisconnected = onDisconnected;
    _client.secure = true;
    //_client.securityContext = securityContext;
    _client.onBadCertificate = ((X509Certificate cert) => false);
    _client.logging(on: true);```

【问题讨论】：

标签： flutter mqtt flutter-web

【解决方案1】：

这对我有用，但我不明白（动态 a）在做什么......也许有人可以更详细地解释它？

void initializeMQTTClient() async {
    _client = MqttServerClient(_host, _identifier);
    _client.port = 8883; //1883
    _client.keepAlivePeriod = 20;
    _client.onDisconnected = onDisconnected;
    _client.secure = true; // false
    _client.logging(on: true);
    _client.securityContext = SecurityContext.defaultContext;
    // _client.useWebSocket = false;
    /// Add the successful connection callback
    _client.onConnected = onConnected;
    _client.onSubscribed = onSubscribed;
    _client.onBadCertificate = (dynamic a) => true;

【讨论】：