ZooKeeper第三方客户端CuratorFramework简介

结论：在使用CuratorFramework的监听机制时，

    如果使用NodeCache，对于多级路径，即使不创建该路径，设置监听后CuratorFramework会主动创建从第一级路径到倒数第二级的路径，比如要监听路径 "/a/b/c" 的NodeCache，CuratorFramework会自动替你创建路径 "/a/b"；

    如果使用PathChildrenCache，对于多级路径，即使不创建该路径，设置监听后CuratorFramework会主动创建整个完整路径，比如要监听路径 "/A/B/C" 的PathChildrenCache，CuratorFramework会自动替你创建路径 "/A/B/C"。

测试代码：

启动程序前，ZooKeeper的节点情况：

[zk: localhost:2181(CONNECTED) 2] ls /

[cluster, brokers, zookeeper, admin, isr_change_notification, log_dir_event_notification, controller_epoch, name, ha, consumers, latest_producer_id_block, config]

节点中并不包含"/A"和"/a"这两个。

启动程序后，ZooKeeper的节点情况：

[zk: localhost:2181(CONNECTED) 3] ls /

[cluster, a, A, brokers, zookeeper, admin, isr_change_notification, log_dir_event_notification, controller_epoch, name, ha, consumers, latest_producer_id_block, config]

再查看其具体路径：

[zk: localhost:2181(CONNECTED) 4] get /a/b

cZxid = 0x125b

ctime = Sun Sep 09 12:43:02 GMT+08:00 2018

mZxid = 0x125b

mtime = Sun Sep 09 12:43:02 GMT+08:00 2018

pZxid = 0x125b

cversion = 0

dataVersion = 0

aclVersion = 0

ephemeralOwner = 0x0

dataLength = 0

numChildren = 0

[zk: localhost:2181(CONNECTED) 5] get /a/b/c

Node does not exist: /a/b/c

[zk: localhost:2181(CONNECTED) 6] get /A/B/C

cZxid = 0x125e

ctime = Sun Sep 09 12:43:02 GMT+08:00 2018

mZxid = 0x125e

mtime = Sun Sep 09 12:43:02 GMT+08:00 2018

pZxid = 0x125e

cversion = 0

dataVersion = 0

aclVersion = 0

ephemeralOwner = 0x0

dataLength = 0

numChildren = 0

可以看出，确实和结论一样。