## 四 ZooKeeper常用命令行操作 - 通过./zkCli.sh 打开zk的客户端进入命令行后台 - ls/ls2 列出当前节点下的子节点 ls2还会列出当前节点的状态 ``` shell [zk: localhost:2181(CONNECTED) 5] ls2 / [cluster, controller_epoch, brokers, zookeeper, admin, isr_change_notification, consumers, log_dir_event_notification, latest_producer_id_block, config] cZxid = 0x0 ctime = Thu Jan 01 08:00:00 CST 1970 mZxid = 0x0 mtime = Thu Jan 01 08:00:00 CST 1970 pZxid = 0x4e cversion = 14 dataVersion = 0 aclVersion = 0 ephemeralOwner = 0x0 dataLength = 0 numChildren = 10 ``` - get 与 stat命令 - stat 列出节点状态 ls2相当于 ls + stat ``` shell [zk: localhost:2181(CONNECTED) 6] stat / cZxid = 0x0 ctime = Thu Jan 01 08:00:00 CST 1970 mZxid = 0x0 mtime = Thu Jan 01 08:00:00 CST 1970 pZxid = 0x4e cversion = 14 dataVersion = 0 aclVersion = 0 ephemeralOwner = 0x0 dataLength = 0 numChildren = 10 ``` - get命令 获取节点内容和节点状态 ``` shell [zk: localhost:2181(CONNECTED) 8] get /zookeeper cZxid = 0x0 #该节点创建（Create）时的id ctime = Thu Jan 01 08:00:00 CST 1970 mZxid = 0x0 #该节点修改（Modify）后的id mtime = Thu Jan 01 08:00:00 CST 1970 pZxid = 0x0 #子节点列表最后一次被修改的事务id cversion = -1 #子节点的版本号 dataVersion = 0 #当前节点数据的版本号 节点数据改变时这个值会变化 aclVersion = 0 # 权限版本, 权限发生变化时版本号回发生变化 ephemeralOwner = 0x0 dataLength = 0 #数据长度 numChildren = 1 #子节点数量 ``` ### 4.2 zk特性 session的基本原理与create命令使用 - 客户端与服务端之间的链接存在Session(会话) - 每个会话可以设置一个超时时间 - 心跳机制: 客户端向服务端的ping包请求 - 心跳结束, session则过期 - Session过期, 则临时节点znode会被抛弃 - create命令 ``` shell [zk: localhost:2181(CONNECTED) 10] create /itheima itheima-data #创建永久节点 Created /itheima [zk: localhost:2181(CONNECTED) 11] get /itheima itheima-data cZxid = 0x50 ctime = Sat Dec 29 17:17:53 CST 2018 mZxid = 0x50 mtime = Sat Dec 29 17:17:53 CST 2018 pZxid = 0x50 cversion = 0 dataVersion = 0 aclVersion = 0 ephemeralOwner = 0x0 dataLength = 12 numChildren = 0 ``` - 创建临时节点 &session过期临时节点删除 ```shell [zk: localhost:2181(CONNECTED) 12] create -e /itheima/tmp itheima-data Created /itheima/tmp [zk: localhost:2181(CONNECTED) 13] get /itheima itheima-data cZxid = 0x50 ctime = Sat Dec 29 17:17:53 CST 2018 mZxid = 0x50 mtime = Sat Dec 29 17:17:53 CST 2018 pZxid = 0x51 cversion = 1 dataVersion = 0 aclVersion = 0 ephemeralOwner = 0x0 dataLength = 12 numChildren = 1 ``` - 创建顺序节点 ``` shell [zk: localhost:2181(CONNECTED) 1] ls /itheima [] [zk: localhost:2181(CONNECTED) 2] create -s /itheima/sec seq Created /itheima/sec0000000001 [zk: localhost:2181(CONNECTED) 3] create -s /itheima/sec seq Created /itheima/sec0000000002 [zk: localhost:2181(CONNECTED) 4] ls /itheima [sec0000000001, sec0000000002] ``` ### 4.3 set/delete 命令 - set命令: ``` shell set path data [version] # set 路径 数据 [版本号] []内为可选参数 ``` - 不传入版本号 ``` shell [zk: localhost:2181(CONNECTED) 17] get /itheima itheima-data1 cZxid = 0x5b ctime = Sat Dec 29 17:45:26 CST 2018 mZxid = 0x66 mtime = Sat Dec 29 18:00:12 CST 2018 pZxid = 0x65 cversion = 5 dataVersion = 1 aclVersion = 0 ephemeralOwner = 0x0 dataLength = 13 numChildren = 3 [zk: localhost:2181(CONNECTED) 18] set /itheima itheima-data2 cZxid = 0x5b ctime = Sat Dec 29 17:45:26 CST 2018 mZxid = 0x67 mtime = Sat Dec 29 18:02:15 CST 2018 pZxid = 0x65 cversion = 5 dataVersion = 2 aclVersion = 0 ephemeralOwner = 0x0 dataLength = 13 numChildren = 3 [zk: localhost:2181(CONNECTED) 19] get /itheima itheima-data2 cZxid = 0x5b ctime = Sat Dec 29 17:45:26 CST 2018 mZxid = 0x67 mtime = Sat Dec 29 18:02:15 CST 2018 pZxid = 0x65 cversion = 5 dataVersion = 2 aclVersion = 0 ephemeralOwner = 0x0 dataLength = 13 numChildren = 3 ``` - 不传入版本号可能会有并发修改问题 可以通过指定版本号类似加锁功能 ```shell [zk: localhost:2181(CONNECTED) 22] set /itheima itheima-data3 1 version No is not valid : /itheima #版本不匹配 修改失败 当前版本2 [zk: localhost:2181(CONNECTED) 23] set /itheima itheima-data3 2 cZxid = 0x5b ctime = Sat Dec 29 17:45:26 CST 2018 mZxid = 0x69 mtime = Sat Dec 29 18:29:21 CST 2018 pZxid = 0x65 cversion = 5 dataVersion = 3 aclVersion = 0 ephemeralOwner = 0x0 dataLength = 13 numChildren = 3 [zk: localhost:2181(CONNECTED) 24] get /itheima itheima-data3 cZxid = 0x5b ctime = Sat Dec 29 17:45:26 CST 2018 mZxid = 0x69 mtime = Sat Dec 29 18:29:21 CST 2018 pZxid = 0x65 cversion = 5 dataVersion = 3 aclVersion = 0 ephemeralOwner = 0x0 dataLength = 13 numChildren = 3 ``` - delete 命令: delete path [version] ``` shell [zk: localhost:2181(CONNECTED) 25] ls /itheima [sec0000000003, sec0000000001, sec0000000002] [zk: localhost:2181(CONNECTED) 27] delete /itheima/sec000000000 sec0000000003 sec0000000001 sec0000000002 [zk: localhost:2181(CONNECTED) 27] delete /itheima/sec0000000001 [zk: localhost:2181(CONNECTED) 28] ls /itheima [sec0000000003, sec0000000002] [zk: localhost:2181(CONNECTED) 29] set /itheima/sec000000000 sec0000000003 sec0000000002 [zk: localhost:2181(CONNECTED) 29] set /itheima/sec0000000002 test2 cZxid = 0x64 ctime = Sat Dec 29 17:49:38 CST 2018 mZxid = 0x6b mtime = Sat Dec 29 18:54:33 CST 2018 pZxid = 0x64 cversion = 0 dataVersion = 1 aclVersion = 0 ephemeralOwner = 0x0 dataLength = 5 numChildren = 0 [zk: localhost:2181(CONNECTED) 30] delete /itheima/sec000000000 sec0000000003 sec0000000002 [zk: localhost:2181(CONNECTED) 30] delete /itheima/sec0000000002 0 version No is not valid : /itheima/sec0000000002 ``` - 总结 使用set / delete命令的时候尽量使用版本号 避免误操作 ### 4.4 watcher机制 - 针对每个节点的操作, 都会有一个监督者->watcher - 当监控的某个对象(znode)发生了变化, 则触发watcher事件 - zk中的watcher是一次性的, 触发后立即销毁 - 父节点, 子节点增删改都能触发其watcher - 针对不同类型的操作, 触发的watcher事件也不同: - (子)节点创建事件 - (子)节点删除事件 - (子)节点数据变化事件 - watcher命令行 - 通过get path [watch]设置watcher - 父节点 增 删 改操作触发 watcher - 子节点 增 删 改操作触发 watcher - 创建父节点触发: NodeCreated - stat path [watch] ``` shell [zk: localhost:2181(CONNECTED) 33] stat /itcast watch Node does not exist: /itcast [zk: localhost:2181(CONNECTED) 35] create /itcast 123 WATCHER::Created /itcast WatchedEvent state:SyncConnected type:NodeCreated path:/itcast ``` - get path [watch] ``` shell [zk: localhost:2181(CONNECTED) 36] get /itcast watch 123 cZxid = 0x6d ctime = Sat Dec 29 19:43:13 CST 2018 mZxid = 0x6d mtime = Sat Dec 29 19:43:13 CST 2018 pZxid = 0x6d cversion = 0 dataVersion = 0 aclVersion = 0 ephemeralOwner = 0x0 dataLength = 3 numChildren = 0 [zk: localhost:2181(CONNECTED) 37] set /itcast 789 WATCHER:: WatchedEvent state:SyncConnected type:NodeDataChanged path:/itcast cZxid = 0x6d ctime = Sat Dec 29 19:43:13 CST 2018 mZxid = 0x6e mtime = Sat Dec 29 19:47:24 CST 2018 pZxid = 0x6d cversion = 0 dataVersion = 1 aclVersion = 0 ephemeralOwner = 0x0 dataLength = 3 numChildren = 0 ``` - ls/ls2 path [watch] ```shell [zk: localhost:2181(CONNECTED) 38] ls /itcast watch [] [zk: localhost:2181(CONNECTED) 39] delete /itcast WATCHER:: WatchedEvent state:SyncConnected type:NodeDeleted path:/itcast ``` - ls为父节点设置watcher, 创建子节点触发:NodeChildrenChanged - ls为父节点设置watcher, 删除子节点触发:NodeChildrenChanged - ls为父节点设置watcher, 修改子节点不触发事件 ``` shell [zk: localhost:2181(CONNECTED) 49] ls /itheima watch [sec0000000003, dir1, sec0000000002] [zk: localhost:2181(CONNECTED) 51] create /itheima/dir2 123 WATCHER::Created /itheima/dir2 WatchedEvent state:SyncConnected type:NodeChildrenChanged path:/itheima [zk: localhost:2181(CONNECTED) 52] ls /itheima watch [sec0000000003, dir2, dir1, sec0000000002] [zk: localhost:2181(CONNECTED) 53] delete /itheima/dir2 WATCHER:: WatchedEvent state:SyncConnected type:NodeChildrenChanged path:/itheima [zk: localhost:2181(CONNECTED) 54] ``` - watcher 使用场景 - 统一资源配置![1546092379014](img/zkshell1.png)