1.1 2 ZooKeeper安装和基本使用

安装要求：JDK版本>=1.6

下载：http://mirrors.cnnic.cn/apache/zookeeper/

1、本地模式

conf/zoo.cfg

tickTime=2000
dataDir=/var/lib/zookeeper
clientPort=2181

tickTime

the basic time unit in milliseconds used by ZooKeeper. It is used to do heartbeats and the minimum session timeout will be twice the tickTime.

dataDir

the location to store the in-memory database snapshots and, unless specified otherwise, the transaction log of updates to the database.

clientPort

the port to listen for client connections

启动

bin/zkServer.sh start

客户端连接

bin/zkCli.sh -server 127.0.0.1:2181

登录后界面

输入help

[zkshell: 0] help
ZooKeeper host:port cmd args
        get path [watch]
        ls path [watch]
        set path data [version]
        delquota [-n|-b] path
        quit
        printwatches on|off
        create path data acl
        stat path [watch]
        listquota path
        history
        setAcl path acl
        getAcl path
        sync path
        redo cmdno
        addauth scheme auth
        delete path [version]
        deleteall path
        setquota -n|-b val path

查看节点

[zk: 127.0.0.1:2181(CONNECTED) 0] ls /
[zookeeper]

create a new znode by running create /zk_test my_data. This creates a new znode and associates the string "my_data" with the node.

[zk: 127.0.0.1:2181(CONNECTED) 1] create /zk_test my_data
Created /zk_test

Issue another ls / command to see what the directory looks like:

[zk: 127.0.0.1:2181(CONNECTED) 0] ls /
[zookeeper, zk_test]

查看节点数据

[zk: 127.0.0.1:2181(CONNECTED) 1]  get /zk_test
my_data
cZxid = 0x4
ctime = Wed Oct 07 21:14:51 CST 2015
mZxid = 0x4
mtime = Wed Oct 07 21:14:51 CST 2015
pZxid = 0x4
cversion = 0
dataVersion = 0
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 7
numChildren = 0

Zxid： Every change to the ZooKeeper state receives a stamp in the form of a zxid (ZooKeeper Transaction Id). This exposes the total ordering of all changes to ZooKeeper. Each change will have a unique zxid and if zxid1 is smaller than zxid2 then zxid1 happened before zxid2.

更新数据

We can change the data associated with zk_test by issuing the set command, as in:

[zk: 127.0.0.1:2181(CONNECTED) 2] set /zk_test junk
cZxid = 0x4
ctime = Wed Oct 07 21:14:51 CST 2015
mZxid = 0x7
mtime = Wed Oct 07 21:17:42 CST 2015
pZxid = 0x4
cversion = 0
dataVersion = 1
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 4
numChildren = 0
[zk: 127.0.0.1:2181(CONNECTED) 3]  get /zk_test   
junk
cZxid = 0x4
ctime = Wed Oct 07 21:14:51 CST 2015
mZxid = 0x7
mtime = Wed Oct 07 21:17:42 CST 2015
pZxid = 0x4
cversion = 0
dataVersion = 1
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 4
numChildren = 0

删除节点

[zk: 127.0.0.1:2181(CONNECTED) 4] delete /zk_test
[zk: 127.0.0.1:2181(CONNECTED) 5] ls /
[zookeeper]
[zk: 127.0.0.1:2181(CONNECTED) 6]

参数说明：

* czxid

The zxid of the change that caused this znode to be created.

* mzxid

The zxid of the change that last modified this znode.

* ctime

The time in milliseconds from epoch when this znode was created.

* mtime

The time in milliseconds from epoch when this znode was last modified.

* version

The number of changes to the data of this znode.

* cversion

The number of changes to the children of this znode.

* aversion

The number of changes to the ACL of this znode.

* ephemeralOwner

The session id of the owner of this znode if the znode is an ephemeral node. If it is not an ephemeral node, it will be zero.

* dataLength

The length of the data field of this znode.

* numChildren

The number of children of this znode.