ZkUtils

    这个是Kafka跟ZK交互的工具类，Kafka在ZK上注册了以下的节点：

val ConsumersPath ="/consumers"//这个路径用于消费者的client.id存储对应消费的offset的路径.

val ClusterIdPath ="/cluster/id"     // clusterid号

val BrokerIdsPath ="/brokers/ids"//这个路径用于存储所有的broker id的路径.

val BrokerTopicsPath ="/brokers/topics"//用于存储每个broker对应的topics的信息,

val ControllerPath ="/controller"   //broker leader

val ControllerEpochPath ="/controller_epoch" //周期

val ReassignPartitionsPath ="/admin/reassign_partitions" //分区的重分配

val DeleteTopicsPath ="/admin/delete_topics"//用于存储删除的topic的信息.

val PreferredReplicaLeaderElectionPath ="/admin/preferred_replica_election"

val BrokerSequenceIdPath ="/brokers/seqid" 

val IsrChangeNotificationPath ="/isr_change_notification"//这个用于在kafka的副本broker发生变化时用于通知的存储路径.

val EntityConfigPath ="/config"

val EntityConfigChangesPath ="/config/changes"