flask blueprint中只用flask插件，以flask-mqtt为例

在Flask Blueprint中使用Flask插件，以Flask-MQTT为例，可以按照以下步骤：

1. 安装Flask-MQTT插件

pip install Flask-MQTT

2. 在Flask应用中初始化Flask-MQTT插件

from flask import Flask
from flask_mqtt import Mqtt

app = Flask(__name__)
app.config['MQTT_BROKER_URL'] = 'localhost'
app.config['MQTT_BROKER_PORT'] = 1883
app.config['MQTT_USERNAME'] = ''
app.config['MQTT_PASSWORD'] = ''
app.config['MQTT_KEEPALIVE'] = 5
app.config['MQTT_TLS_ENABLED'] = False

mqtt = Mqtt(app)

3. 创建Flask Blueprint并注册路由

from flask import Blueprint

mqtt_bp = Blueprint('mqtt', __name__, url_prefix='/mqtt')

@mqtt_bp.route('/publish')
def publish():
    mqtt.publish('test_topic', 'Hello, World!')
    return 'Message published'

@mqtt_bp.route('/subscribe')
def subscribe():
    def handle_message(client, userdata, message):
        print(message.topic, message.payload.decode())
    mqtt.subscribe('test_topic')
    mqtt.on_message(handle_message)
    return 'Subscribed to test_topic'

4. 注册Flask Blueprint到Flask应用中

app.register_blueprint(mqtt_bp)

现在，你可以通过访问`/mqtt/publish`和`/mqtt/subscribe`路由来发布和订阅MQTT消息。