最近因需要用python写一个微服务来用MQTT给硬件传输图片，其中python用的是flask框架，大概流程如下：

协议为：

需要将图片数据封装成多个消息进行传输，每个消息传输的数据字节数为1400Byte。
消息(MQTT Payload) 格式：Web服务器-------->BASE：

反馈：BASE---------> Web服务器:

如果Web服务器发送完一个“数据传输消息”后，5S内没有收到MQTT“反馈消息”或者收到的反馈中显示“数据包不完整”，则重发该“数据传输消息”。

程序流程图

根据上面的协议，可以得到如下的流程图：

代码如下：

# encoding:utf-8from flask import Flask, jsonifyfrom flask_restful import Api, Resource, reqparsefrom PIL import Imagefrom io import BytesIOimport requestsimport os, logging, timeimport paho.mqtt.client as mqttimport structfrom flask_cors import *# 日志配置信息logging.basicConfig( level=logging.INFO, format='%(asctime)s - %(name)s - %(levelname)s - %(message)s （runing by %(funcName)s',)class Mqtt(object): def __init__(self, img_data, size): self.MQTTHOST = '*******' self.MQTTPORT = "******" # 订阅和发送的主题 self.topic_from_base = 'mqttTestSub' self.topic_to_base = 'mqttTestPub' self.client_id = time.strftime('%Y%m%d%H%M%S', time.localtime(time.time())) self.client = mqtt.Client(self.client_id) # 完成链接后的回掉函数 self.client.on_connect = self.on_connect # 图片大小 self.size = size # 用于跳出死循环，结束任务 self.finished = None # 包的编号 self.index = 0 # 将收到的图片数据按大小分成列表 self.image_data_list = [img_data[x:x + 1400] for x in range(0, self.size, 1400)] # 记录发布后的数据，用于监控时延 self.pub_time = 0 self.header_to_base = 0xffffeeee self.header_from_base = 0xeeeeffff # 功能标识 self.function_begin = 0x01 self.function_doing = 0x02 self.function_finished = 0x03 # 包的完整和非完整状态 self.whole_package = 0x01 self.bad_package = 0x00 # 头信息的格式,小端模式 self.format_to_base = "<Lbhh" self.format_from_base = "<Lbhb" # 如果重发包时，用于检查是否重发第一个包 self.first = True # 如果重发包时，用于检查是否重发最后一个包 self.last = False self.begin_data = 'image.jpg;' + str(self.size) # 链接mqtt服务器函数 def on_mqtt_connect(self): self.client.connect(self.MQTTHOST, self.MQTTPORT, 60) self.client.loop_start() # 链接完成后的回调函数 def on_connect(self, client, userdata, flags, rc): logging.info("+++ Connected with result code {} +++".format(str(rc))) self.client.subscribe(self.topic_from_base) # 订阅函数 def subscribe(self): self.client.subscribe(self.topic_from_base, 1) # 消息到来处理函数 self.client.on_message = self.on_message # 接收到信息后的回调函数 def on_message(self, client, userdata, msg): # 如果接受第一个包则不需要重发第一个 self.first = False # 将接受到的包进行解压，得到一个元组 base_tuple = struct.unpack(self.format_from_base, msg.payload) logging.info("+++ imageData's letgth is {}, base_tupe is {} +++".format(self.size, base_tuple)) logging.info("+++ package_number is {}, package_status_from_base is {} +++" .format(base_tuple[2], base_tuple[3])) # 检查接受到信息的头部是否正确 if base_tuple[0] == self.header_from_base: logging.info("+++ function_from_base is {} +++".format(base_tuple[1])) # 是否完成传输，如果完成则退出 if base_tuple[1] == self.function_finished: logging.info("+++ finish work +++") self.finished = 1 self.client.disconnect() else: # 是否是最后一个包 if self.index == len(self.image_data_list) - 1: self.publish('finished', self.function_finished) self.last = True logging.info("+++ finished_data_to_base is finished+++") else: # 如果接收到的包不是 0x03则进行传送数据 if base_tuple[1] == self.function_begin or base_tuple[1] == self.function_doing: logging.info("+++ package_number is {}, package_status_from_base is {} +++" .format(base_tuple[2],base_tuple[3])) # 如果数据的反馈中，包的状态是1则继续发下一个包 if base_tuple[3] == self.whole_package: self.publish(self.index, self.function_doing) logging.info("+++ data_to_base is finished+++") self.index += 1 # 如果数据的反馈中，包的状态是0则重发数据包 elif base_tuple[3] == self.bad_package: re_package_number = base_tuple[2] self.publish(re_package_number-1, self.function_doing) logging.info("+++ re_data_to_base is finished+++") else: logging.info("+++ package_status_from_base is not 0 or 1 +++") self.client.disconnect() else: logging.info("+++ function_identifier is illegal +++") self.client.disconnect() else: logging.info("+++ header_from_base is illegal +++") self.client.disconnect() # 数据发送函数 def publish(self, index, fuc): # 看是否是最后一个包 if index == 'finished': length = 0 package_number = 0 data = b'' else: length = len(self.image_data_list[index]) package_number = index data = self.image_data_list[index] # 打包数据头信息 buffer = struct.pack( self.format_to_base, self.header_to_base, fuc, package_number, length ) to_base_data = buffer + data # mqtt发送 self.client.publish( self.topic_to_base, to_base_data ) self.pub_time = time.time() # 发送第一个包函数 def publish_begin(self): buffer = struct.pack( self.format_to_base, self.header_to_base, self.function_begin, 0, len(self.begin_data.encode('utf-8')), ) begin_data = buffer + self.begin_data.encode('utf-8') self.client.publish(self.topic_to_base, begin_data) # 控制函数 def control(self): self.on_mqtt_connect() self.publish_begin() begin_time = time.time() self.pub_time = time.time() self.subscribe() while True: time.sleep(1) # 超过5秒重传 date = time.time() - self.pub_time if date > 5: # 是否重传第一个包 if self.first == True: self.publish_begin() logging.info('+++ this is timeout first_data +++') # 是否重传最后一个包 elif self.last == True: self.publish('finished', self.function_finished) logging.info('+++ this is timeout last_data +++') else: self.publish(self.index-1, self.function_doing) logging.info('+++ this is timeout middle_data +++') if self.finished == 1: logging.info('+++ all works is finished+++') break print(str(time.time()-begin_time) + 'begin_time - end_time')app = Flask(__name__)api = Api(app)CORS(app, supports_credentials=True)# 接受参数parser = reqparse.RequestParser()parser.add_argument('url', help='mqttImage url', location='args', type=str)class GetImage(Resource): # 得到参数并从图床下载到本地 def get(self): args = parser.parse_args() url = args.get('url') response = requests.get(url) # 获取图片 image = Image.open(BytesIO(response.content)) # 存取图片 add = os.path.join(os.path.abspath(''), 'image.jpg') image.save(add) # 得到图片大小 size = os.path.getsize(add) f = open(add, 'rb') imageData = f.read() f.close() # 进行mqtt传输 mqtt = Mqtt(imageData, size) mqtt.control() # 删除文件 os.remove(add) logging.info('*** the result of control is {} ***'.format(1)) return jsonify({ "imageData": 1 })api.add_resource(GetImage, '/image')if __name__ == '__main__': app.run(debug=True, host='0.0.0.0')

总结

以上所述是小编给大家介绍的python使用MQTT给硬件传输图片的实现方法,希望对大家有所帮助，如果大家有任何疑问请给我留言，小编会及时回复大家的。在此也非常感谢大家对网站的支持！
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