简介

kafka是最近几年很流行的消息队列中间件。在大数据以及后端服务领域有很广泛的应用。废话不多说，接下来直接上代码介绍python如何向kafka发送数据以及订阅数据。

消息发布

Kafka的消息是 " 发布--订阅" 模式的。 接下来先介绍向kakfa发布消息。先安装python的kafka连接模块。pip install kafka-python.

import time
from kafka import KafkaProducer


class KafkaMsgProducer:
    def __init__(self, server):
        self._server = server
        self.producer = None

    def connect(self):
        if self.producer is None:
            producer = KafkaProducer(bootstrap_servers=self._server)
            self.producer = producer

    def close(self):
        if self.producer is not None:
            self.producer.close()
            self.producer = None

    def send(self, topic, msg):
        if self.producer is not None:
            if not isinstance(msg, bytes):
                msg = msg.encode("utf-8")  # 将str类型转换为bytes类型
            self.producer.send(topic=topic, value=msg)


def run():
    producer = KafkaMsgProducer("localhost:9092")
    producer.connect()  # 建立连接
    topic = "YanChampion-Test"

    print("Start sending msg to kafka!")

    for msg in "Hello! This is YanChampion speaking!".split():
        producer.send(topic=topic, msg=msg)   # 向kafka 指定topic发送数据
        time.sleep(1)


if __name__ == '__main__':
    run()    # 运行发布消息程序

以上代码即可以向kafka指定topic发布消息了。注意，为了测试，先不运行producer.py

消息订阅

 import time
from kafka import KafkaProducer


class KafkaMsgProducer:
    def __init__(self, server):
        self._server = server
        self.producer = None

    def connect(self):
        if self.producer is None:
            producer = KafkaProducer(bootstrap_servers=self._server)
            self.producer = producer

    def close(self):
        if self.producer is not None:
            self.producer.close()
            self.producer = None

    def send(self, topic, msg):
        if self.producer is not None:
            if not isinstance(msg, bytes):
                msg = msg.encode("utf-8")  # 将str类型转换为bytes类型
            self.producer.send(topic=topic, value=msg)


def run():
    producer = KafkaMsgProducer("localhost:9092")
    producer.connect()  # 建立连接
    topic = "YanChampion-Test"

    print("Start sending msg to kafka!")

    for msg in " 111 222 333 444".split():
        producer.send(topic=topic, msg=msg)   # 向kafka 指定topic发送数据
        time.sleep(1)


if __name__ == '__main__':
    run()    # 运行程序

以上代码即可完成消息的订阅。

测试

因为kafka是 发布-定于模式。所以，一个topic可以有多个consumer订阅，并且，每个consumer都可以收到同一条消息。那么让我们先来运行两个consumer.py文件。
打开不同的终端
python3 consumer.py
接下来再运行producer.py
python3 producer.py

通过观察，最终可以看到，两个运行了consumer.py 的终端 都可以收到消息

[root@yanchampion kafka-demo]# python3 consumer.py 
收到消息： b'111'
收到消息： b'222'
收到消息： b'333'
收到消息： b'444'