Python脚本消费kafka数据

kafka简介（摘自百度百科）

一、简介：
详见：https://blog.csdn.net/Beyond_F4/article/details/80310507

二、安装
详见博客：https://blog.csdn.net/beyond_f4/article/details/80095689              

三、按照官网的样例，先跑一个应用
1、生产者:
from kafka import KafkaProducer

producer = KafkaProducer(bootstrap_servers=['172.21.10.136:9092'])  #此处ip可以是多个['0.0.0.1:9092','0.0.0.2:9092','0.0.0.3:9092' ]

for i in range(3):
    msg = "msg%d" % i
    producer.send('test', msg)
producer.close()

2、消费者(简单demo):
from kafka import KafkaConsumer

consumer = KafkaConsumer('test',
                         bootstrap_servers=['172.21.10.136:9092'])
                         
for message in consumer:
    print ("%s:%d:%d: key=%s value=%s" % (message.topic, message.partition,
                                          message.offset, message.key,
                                          message.value))


启动后生产者、消费者可以正常消费。

3、消费者(消费群组)
from kafka import KafkaConsumer

consumer = KafkaConsumer('test',
                         group_id='my-group',
                         bootstrap_servers=['172.21.10.136:9092'])
                         
for message in consumer:
    print ("%s:%d:%d: key=%s value=%s" % (message.topic, message.partition,
                                          message.offset, message.key,
                                          message.value))
                                          
启动多个消费者，只有其中可以可以消费到，满足要求，消费组可以横向扩展提高处理能力

4、消费者(读取目前最早可读的消息)
from kafka import KafkaConsumer

consumer = KafkaConsumer('test',
                         auto_offset_reset='earliest',
                         bootstrap_servers=['172.21.10.136:9092'])
                         
for message in consumer:
    print ("%s:%d:%d: key=%s value=%s" % (message.topic, message.partition,
                                          message.offset, message.key,
                                          message.value))
                                         
auto_offset_reset:重置偏移量，earliest移到最早的可用消息，latest最新的消息，默认为latest
源码定义:{'smallest': 'earliest', 'largest': 'latest'}

5、消费者(手动设置偏移量)
from kafka import KafkaConsumer
from kafka.structs import TopicPartition

consumer = KafkaConsumer('test',
                         bootstrap_servers=['172.21.10.136:9092'])

print consumer.partitions_for_topic("test")  #获取test主题的分区信息
print consumer.topics()  #获取主题列表
print consumer.subscription()  #获取当前消费者订阅的主题
print consumer.assignment()  #获取当前消费者topic、分区信息
print consumer.beginning_offsets(consumer.assignment()) #获取当前消费者可消费的偏移量
consumer.seek(TopicPartition(topic=u'test', partition=0), 5)  #重置偏移量，从第5个偏移量消费
for message in consumer:
    print ("%s:%d:%d: key=%s value=%s" % (message.topic, message.partition,
                                          message.offset, message.key,
                                          message.value))
                                          
6、消费者(订阅多个主题)
from kafka import KafkaConsumer
from kafka.structs import TopicPartition

consumer = KafkaConsumer(bootstrap_servers=['172.21.10.136:9092'])
consumer.subscribe(topics=('test','test0'))  #订阅要消费的主题
print consumer.topics()
print consumer.position(TopicPartition(topic=u'test', partition=0)) #获取当前主题的最新偏移量
for message in consumer:
    print ("%s:%d:%d: key=%s value=%s" % (message.topic, message.partition,
                                          message.offset, message.key,
                                          message.value))
                                          
7、消费者(手动拉取消息)
from kafka import KafkaConsumer
import time

consumer = KafkaConsumer(bootstrap_servers=['172.21.10.136:9092'])
consumer.subscribe(topics=('test','test0'))
while True:
    msg = consumer.poll(timeout_ms=5)   #从kafka获取消息
    print msg
    time.sleep(1)
    
8、消费者(消息挂起与恢复)
from kafka import KafkaConsumer
from kafka.structs import TopicPartition
import time

consumer = KafkaConsumer(bootstrap_servers=['172.21.10.136:9092'])
consumer.subscribe(topics=('test'))
consumer.topics()
consumer.pause(TopicPartition(topic=u'test', partition=0))
num = 0
while True:
    print num
    print consumer.paused()   #获取当前挂起的消费者
    msg = consumer.poll(timeout_ms=5)
    print msg
    time.sleep(2)
    num = num + 1
    if num == 10:
        print "resume..."
        consumer.resume(TopicPartition(topic=u'test', partition=0))
        print "resume......"
        
pause执行后，consumer不能读取，直到调用resume后恢复。

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