python mqtt的訂閱與發布

寫測試代碼時用到的，借助了網上許多教程也踩了很多坑。

class MQTTClient(object):
    def __init__(self, host, port):
        # Initialize MQTT client.
        self._client = mqtt.Client()  #create MQTT client
        self.host = host
        self.port = port
        #self.topic = topic
        #self.obj_id = obj_id
        self.on_message = None
        self.msg_topic = None
        self.msg_payload = None
        self._client.on_connect = self._on_connect
        #self._client.on_disconnect = self._mqtt_disconnect
        self._client.on_message = self._on_message
        self._connected = False
        self._client.on_publish = self._on_publish
    
    def connect(self, username, password):
        self._client.username_pw_set(username, password)
        self._client.connect(self.host, self.port, 60)

    def _on_connect(self, client, userdata, flags, rc):
        logging.info("Client on_connect called.")
        logging.info("Connected with result code "+str(rc))
        self._client.subscribe("compass/event/monitor/e100.zxy.car9")
        #self._client.on_message = self._on_message

    def is_connected(self):
        return self._connected

    def _on_message(self, client, userdata, msg):
        #logging.info("Client on_message called.")
        #print(msg.topic+" "+str(msg.payload))
        self.msg_topic = msg.topic
        self.msg_payload = str(msg.payload)
        self.on_message(self, msg.topic, str(msg.payload))

    def _on_publish(self, client, userdata, result):
        #logging.info("data published")
        pass

    '''
    def _on_subscribe(self, client, userdata, result):
        #logging.info("data published")
        pass
    '''
    def loop(self, timeout_sec=0.5):
        #self._client.loop_forever()
        self._client.loop(timeout=timeout_sec)
    '''
    def on_subscribe(self, topic, obj_id, qos):
        self._client.subscribe("compass/event/monitor/e100.zxy.car9", qos)
        print "@@@@@@@2"
        self._client.on_message = self._on_message
        print  "######"
    '''
    def on_publish(self, topic, msg, qos):
        self._client.publish(topic, payload=str(msg), qos=qos)

訂閱調用：

client = MQTTClient(MQTT_HOST, MQTT_PORT)
client.connect(MQTT_USER, MQTT_PASS)
start = time.time()
while (time.time() - start) < self.TIMEOUT_SEC:
    client.loop()
    if client.msg_topic != None and client.msg_payload != None:
        if eval(client.msg_payload)["type"] == "dcu_connection":
            break
發布調用：

client = MQTTClient(MQTT_HOST, MQTT_PORT)
client.connect(MQTT_USER, MQTT_PASS)

client.on_publish("/" + CLOUD_BACKEND + "/tracking", rsu_msg, 1)