Azure IoTHub DeviceMessage，消息正文上的路由筛选器不起作用

Question

我正在按照https://docs.microsoft.com/en-us/azure/iot-hub/iot-hub-monitoring-notifications-with-azure-logic-apps中所述的说明使用Azure Logic Apps创建IoT远程监视和通知。

遥测模拟器（使用com.microsoft.azure.sdk.iot的Java-> iot-device-client-> 1.14.0版本）

public class SimulatedDevice {
    // The device connection string to authenticate the device with your IoT hub.
    // Using the Azure CLI:
    // az iot hub device-identity show-connection-string --hub-name {YourIoTHubName}
    // --device-id MyJavaDevice --output table
    private static String connString = "#ConnectionString";

    private static IotHubClientProtocol protocol = IotHubClientProtocol.AMQPS;
    private static DeviceClient client;

    // Specify the telemetry to send to your IoT hub.
    private static class TelemetryDataPoint {
        public double temperature;
        public double humidity;
        public String isTrue = "true";

        // Serialize object to JSON format.
        public String serialize() {
            Gson gson = new Gson();
            return gson.toJson(this);
        }
    }

    // Print the acknowledgement received from IoT Hub for the telemetry message
    // sent.
    private static class EventCallback implements IotHubEventCallback {
        public void execute(IotHubStatusCode status, Object context) {
            System.out.println("IoT Hub responded to message with status: " + status.name());

            if (context != null) {
                synchronized (context) {
                    context.notify();
                }
            }
        }
    }

    private static class MessageSender implements Runnable {
        public void run() {
            try {
                // Initialize the simulated telemetry.
                double minTemperature = 20;
                double minHumidity = 60;
                Random rand = new Random();
                int i = 0;

                while (i < 100000) {
                    // Simulate telemetry.
                    double currentTemperature = minTemperature + rand.nextDouble() * 15;
                    double currentHumidity = minHumidity + rand.nextDouble() * 20;
                    TelemetryDataPoint telemetryDataPoint = new TelemetryDataPoint();
                    telemetryDataPoint.temperature = currentTemperature;
                    telemetryDataPoint.humidity = currentHumidity;

                    // Add the telemetry to the message body as JSON.
                    String msgStr = telemetryDataPoint.serialize();

                    byte[] bodyClone = msgStr.getBytes(StandardCharsets.UTF_8);
                    Message msg = new Message(bodyClone);

                    // Add a custom application property to the message.
                    // An IoT hub can filter on these properties without access to the message body.
                    msg.setProperty("temperatureAlert", (currentTemperature > 30) ? "true" : "false");
                    msg.setMessageType(MessageType.DEVICE_TELEMETRY);

                    System.out.println("Sending message string: " + msgStr);
                    System.out.println("Sending message: " + msg);

                    Object lockobj = new Object();

                    // Send the message.
                    EventCallback callback = new EventCallback();
                    client.sendEventAsync(msg, callback, lockobj);

                    synchronized (lockobj) {
                        lockobj.wait();
                    }
                    Thread.sleep(1000);
                }
            } catch (InterruptedException e) {
                System.out.println("Finished.");
            }
        }
    }

    public static void main(String[] args) throws IOException, URISyntaxException {

        // Connect to the IoT hub.
        client = new DeviceClient(connString, protocol);
        client.open();

        // Create new thread and start sending messages
        MessageSender sender = new MessageSender();
        ExecutorService executor = Executors.newFixedThreadPool(1);
        executor.execute(sender);

        // Stop the application.
        System.out.println("Press ENTER to exit.");
        System.in.read();
        executor.shutdownNow();
        client.closeNow();
    }
}

对于QueryString-temperatureAlert =“ true”-一切正常。但是对于查询字符串-$ body.temperature> 30-那么我没有收到任何消息。

Answer 1

为了让IoT中心知道消息是否可以基于其主体内容进行路由，消息必须包含描述其内容和主体编码的特定标头。特别是，消息必须同时具有以下两个标头才能在消息正文上进行路由：

1. “ application / json”的内容类型
2. 内容编码必须符合以下条件之一：
   • “ utf-8”
   • “ utf-16”
   • “ utf-32”

在下面的两行下面添加以下语法以创建Message对象：

msg.setContentEncoding("utf-8");
msg.setContentType("application/json");