org.apache.kafka.clients.consumer.KafkaConsumer(一)
*AclientthatconsumesrecordsfromaKafkacluster.*kafka客户端从kafka集群消费消息(获取消息)*ThisclienttransparentlyhandlesthefailureofKafkabrokers,andtransparentlyadaptsastopicpartitionsitfetchesmigratewithinthecluster.