尝试连接 MQTT 时机器不在网络上？

问题描述

您好，我的应用程序中的开发人员执行两项操作，一项是以编程方式提供SSID 和密码 来连接特定的wifi，另一项是与MQTT。两种操作都可以单独正常工作，但是当第一次以编程方式连接到 WIFI 之后，如果我尝试连接 MQTT，它会抛出 异常。 >

MqttException (0) - java.net.socketException: socket Failed: ENONET (Machine is not on the network)
1608792187.259 31589-31589/com.asiczen.azlock W/System.err:     at org.eclipse.paho.client.mqttv3.internal.ExceptionHelper.createMqttException(ExceptionHelper.java:38)
1608792187.259 31589-31589/com.asiczen.azlock W/System.err:     at org.eclipse.paho.client.mqttv3.internal.ClientComms$ConnectBG.run(ClientComms.java:690)
1608792187.259 31589-31589/com.asiczen.azlock W/System.err:     at java.lang.Thread.run(Thread.java:919)

这是我的 Wifi 连接。

private void connectToBrideAboveQ(String networkSSID,String networkPass){
        WifiNetworkSpecifier.Builder builder = new WifiNetworkSpecifier.Builder();
        builder.setSsid(networkSSID);
        builder.setWpa2Passphrase(networkPass);

        WifiNetworkSpecifier wifiNetworkSpecifier = builder.build();

        NetworkRequest.Builder networkRequestBuilder = new NetworkRequest.Builder();
        networkRequestBuilder.addTransportType(NetworkCapabilities.TRANSPORT_WIFI);
        networkRequestBuilder.removeCapability(NetworkCapabilities.NET_CAPABILITY_INTERNET);
        networkRequestBuilder.setNetworkSpecifier(wifiNetworkSpecifier);

        NetworkRequest networkRequest = networkRequestBuilder.build();
        cm = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);

        networkCallback = new ConnectivityManager.NetworkCallback(){
            @Override
            public void onAvailable(@NonNull Network network) {
                super.onAvailable(network);
                Toast.makeText(MainActivity.this,"Connected",Toast.LENGTH_SHORT).show();
                Log.d(TAG,"onAvailable: "+network);
                cm.bindProcesstoNetwork(network);
            }
        };
        cm.requestNetwork(networkRequest,networkCallback);

    }

这里是 mqtt 连接代码

mqttConnectOptions = new MqttConnectOptions();
mqttConnectOptions.setCleanSession(true);
mqttClient = new MqttAndroidClient(this,url,id);
        mqttClient.setCallback(new MqttCallback() {
            @Override
            public void connectionLost(Throwable throwable) {
                doConnectTask = true;
                Log.d(TAG,"MQTT connectionLost: ");
            }

            @Override
            public void messageArrived(String s,MqttMessage mqttMessage) throws Exception {

            }

            @Override
            public void deliveryComplete(IMqttDeliveryToken iMqttDeliveryToken) {

            }
        });

mqttClient.connect(mqttConnectOptions,null,new IMqttActionListener() {
                    @Override
                    public void onSuccess(IMqttToken iMqttToken) {
                        Log.d(TAG,"MQTT CONNECTED: ");
                    }

                    @Override
                    public void onFailure(IMqttToken iMqttToken,Throwable throwable) {
                        doConnectTask = true;
                        //setNewMqttClient();
                        throwable.printstacktrace();
                        Log.d(TAG,"MQTT FAILER onFailure: ");
                    }
                });

提前致谢

解决方法

最后我在连接到 MQTT 之前解决了这个问题，只需调用 cm.bindProcessToNetwork(null); 这解决了我的问题。