zookeeper 基本命令和java api

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1.Zookeeper命令工具

启动zookeeper服务后，连接到zookeeper服务：

    zkServer -server localhost:2181

执行结果如下：

Connecting to localhost:2181
2018-06-10 03:52:52,540 [myid:] - INFO  [main:Environment@100] - Client environment:zookeeper.version=3.4.10-39d3a4f269333c922ed3db283be479f9deacaa0f, built on 03/23/2017 10:13 GMT
2018-06-10 03:52:52,562 [myid:] - INFO  [main:Environment@100] - Client environment:host.name=192.168.15.201
2018-06-10 03:52:52,563 [myid:] - INFO  [main:Environment@100] - Client environment:java.version=1.8.0_171
2018-06-10 03:52:52,578 [myid:] - INFO  [main:Environment@100] - Client environment:java.vendor=Oracle Corporation
2018-06-10 03:52:52,579 [myid:] - INFO  [main:Environment@100] - Client environment:java.home=/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.171-8.b10.el6_9.x86_64/jre
2018-06-10 03:52:52,579 [myid:] - INFO  [main:Environment@100] - Client environment:java.class.path=/usr/local/zookeeper/zookeeper-3.4.10_1/bin/../build/classes:/usr/local/zookeeper/zookeeper-3.4.10_1/bin/../build/lib/*.jar:/usr/local/zookeeper/zookeeper-3.4.10_1/bin/../lib/slf4j-log4j12-1.6.1.jar:/usr/local/zookeeper/zookeeper-3.4.10_1/bin/../lib/slf4j-api-1.6.1.jar:/usr/local/zookeeper/zookeeper-3.4.10_1/bin/../lib/netty-3.10.5.Final.jar:/usr/local/zookeeper/zookeeper-3.4.10_1/bin/../lib/log4j-1.2.16.jar:/usr/local/zookeeper/zookeeper-3.4.10_1/bin/../lib/jline-0.9.94.jar:/usr/local/zookeeper/zookeeper-3.4.10_1/bin/../zookeeper-3.4.10.jar:/usr/local/zookeeper/zookeeper-3.4.10_1/bin/../src/java/lib/*.jar:/usr/local/zookeeper/zookeeper-3.4.10_1/bin/../conf:.:/usr/lib/jvm/jre-1.8.0-openjdk-1.8.0.171-8.b10.el6_9.x86_64/lib/dt.jar:/usr/lib/jvm/jre-1.8.0-openjdk-1.8.0.171-8.b10.el6_9.x86_64/lib/tools.jar
2018-06-10 03:52:52,579 [myid:] - INFO  [main:Environment@100] - Client environment:java.library.path=/usr/java/packages/lib/amd64:/usr/lib64:/lib64:/lib:/usr/lib
2018-06-10 03:52:52,580 [myid:] - INFO  [main:Environment@100] - Client environment:java.io.tmpdir=/tmp
2018-06-10 03:52:52,580 [myid:] - INFO  [main:Environment@100] - Client environment:java.compiler=<NA>
2018-06-10 03:52:52,581 [myid:] - INFO  [main:Environment@100] - Client environment:os.name=Linux
2018-06-10 03:52:52,581 [myid:] - INFO  [main:Environment@100] - Client environment:os.arch=amd64
2018-06-10 03:52:52,582 [myid:] - INFO  [main:Environment@100] - Client environment:os.version=2.6.32-431.el6.x86_64
2018-06-10 03:52:52,582 [myid:] - INFO  [main:Environment@100] - Client environment:user.name=root
2018-06-10 03:52:52,582 [myid:] - INFO  [main:Environment@100] - Client environment:user.home=/root
2018-06-10 03:52:52,583 [myid:] - INFO  [main:Environment@100] - Client environment:user.dir=/usr/local/zookeeper/zookeeper-3.4.10/bin
2018-06-10 03:52:52,589 [myid:] - INFO  [main:ZooKeeper@438] - Initiating client connection, connectString=localhost:2181 sessionTimeout=30000 watcher=org.apache.zookeeper.ZooKeeperMain$MyWatcher@25f38edc
Welcome to ZooKeeper!
2018-06-10 03:52:52,716 [myid:] - INFO  [main-SendThread(localhost:2181):ClientCnxn$SendThread@1032] - Opening socket connection to server localhost/0:0:0:0:0:0:0:1:2181. Will not attempt to authenticate using SASL (unknown error)
JLine support is enabled
2018-06-10 03:52:53,237 [myid:] - INFO  [main-SendThread(localhost:2181):ClientCnxn$SendThread@876] - Socket connection established to localhost/0:0:0:0:0:0:0:1:2181, initiating session
2018-06-10 03:52:53,507 [myid:] - INFO  [main-SendThread(localhost:2181):ClientCnxn$SendThread@1299] - Session establishment complete on server localhost/0:0:0:0:0:0:0:1:2181, sessionid = 0x163e94ed0530000, negotiated timeout = 30000

WATCHER::

WatchedEvent state:SyncConnected type:None path:null

控制台会输出一些配置信息和“welcome to Zookeeper”，查看zookeeper的相关操作，可以输入 help 命令

[zk: localhost:2181(CONNECTED) 4] help
ZooKeeper -server host:port cmd args
stat path [watch]
set path data [version]
ls path [watch]
delquota [-n|-b] path
ls2 path [watch]
setAcl path acl
setquota -n|-b val path
history 
redo cmdno
printwatches on|off
delete path [version]
sync path
listquota path
rmr path
get path [watch]
create [-s] [-e] path data acl
addauth scheme auth
quit 
getAcl path
close 
connect host:port

演示下常见的zookeeper基本操作

1.创建一个节点

节点的名字是zoo，节点的相关信息是myData

[zk: localhost:2181(CONNECTED) 4] create /zoo myData
Created /zoo

再查看下现在zookeeper包含的节点

[zk: localhost:2181(CONNECTED) 6] ls /
[zoo, zookeeper]

这时，可以看到zoo节点已经被创建

2.获取指定节点的信息

[zk: localhost:2181(CONNECTED) 7] get /zoo
myData
cZxid = 0x100000006
ctime = Sun Jun 10 10:35:55 PDT 2018
mZxid = 0x100000006
mtime = Sun Jun 10 10:35:55 PDT 2018
pZxid = 0x100000006
cversion = 0
dataVersion = 0
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 6
numChildren = 0

3.修改指定节点的信息

[zk: localhost:2181(CONNECTED) 8] set /zoo animais
cZxid = 0x100000006
ctime = Sun Jun 10 10:35:55 PDT 2018
mZxid = 0x100000007
mtime = Sun Jun 10 10:39:06 PDT 2018
pZxid = 0x100000006
cversion = 0
dataVersion = 1
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 7
numChildren = 0

再查看修改后内容

[zk: localhost:2181(CONNECTED) 9] get /zoo        
animais
cZxid = 0x100000006
ctime = Sun Jun 10 10:35:55 PDT 2018
mZxid = 0x100000007
mtime = Sun Jun 10 10:39:06 PDT 2018
pZxid = 0x100000006
cversion = 0
dataVersion = 1
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 7
numChildren = 0

4.删除节点

[zk: localhost:2181(CONNECTED) 12] delete /zoo
[zk: localhost:2181(CONNECTED) 13] ls /
[zookeeper]

结验证，zoo节点已被删除

2.java API的使用

首先需要在maven添加zookeeper的jar包

    <dependency>
        <groupId>org.apache.zookeeper</groupId>
        <artifactId>zookeeper</artifactId>
        <version>3.4.10</version>
    </dependency>

具体代码如下：

public class ZookeeperDemo {
    /** 服务地址，ip:port，多个地址用逗号隔开 */
    private static final String SERVER_ADDRESS = "192.168.2.201:218,192.168.2.201:2182,192.168.2.201:2183";
    /** 超时时间，毫秒为单位 */
    private static final Integer TIMEOUT_MS = 3000;
    /** 节点名 */
    private static final String NODE_ZOO = "/zoo/mammal";

    public static void main(String[] args) throws Exception {
        ZooKeeper zk = new ZooKeeper(SERVER_ADDRESS, TIMEOUT_MS, new DemoWatcher());
        waitUntilConnected(zk);
        // 判断节点是否存在
        Stat stat = zk.exists(NODE_ZOO, false);

        if (null == stat) {// 节点不存在
            createNode(zk, NODE_ZOO, "i'm mammal", ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
        } else {
            getData(zk, NODE_ZOO, stat);
            System.out.println(stat.getVersion());

            updateNode(zk, NODE_ZOO, "i'm mammal haha", stat.getVersion());
        }
    }

    /**
     * 根据指定节点名字，创建节点
     * @param zk               zk客户端
     * @param node_zoo         节点名
     * @param data             节点信息
     * @param ACL_LIST         访问控制列表，这里使用了完全开放的ACL，允许任何客户端对znode进行读写
     * @param createMode       创建znode的类型：有两种类型的znode：短暂的和持久的。
     * @throws KeeperException
     * @throws InterruptedException
     */
    public static void createNode(ZooKeeper zk, String node_zoo, String data,List<ACL> ACL_LIST,CreateMode createMode)
            throws KeeperException, InterruptedException {
        String createResult = zk.create(node_zoo, data.getBytes(), ACL_LIST ,createMode);
        System.out.println(createResult);
    }

    /**
     * 删除节点
     * @param zk               zk客户端
     * @param node_zoo         节点名
     * @param version          指定的版本，-1/无视版本
     * @throws KeeperException
     * @throws InterruptedException
     */
    public static void deleteNode(ZooKeeper zk, String node_zoo, Integer version)
            throws KeeperException, InterruptedException {
        zk.delete(node_zoo, version);
    }

    /**
     * 更新节点
     * @param zk               zk客户端
     * @param node_zoo         节点名
     * @param data             节点数据
     * @param version          指定的版本，-1/无视版本
     * @throws KeeperException
     * @throws InterruptedException
     */
    public static void updateNode(ZooKeeper zk, String node_zoo, String data, Integer version)
            throws KeeperException, InterruptedException {
        zk.setData(node_zoo, data.getBytes(), version);
    }

    /**
     * 根据节点名获取节点信息
     * @param zk               zk客户端
     * @param node_zoo         节点名
     * @param stat             节点状态
     * @throws KeeperException
     * @throws InterruptedException
     */
    public static void getData(ZooKeeper zk, String node_zoo, Stat stat) throws KeeperException, InterruptedException {
        byte[] bs = zk.getData(node_zoo, false, stat);
        System.out.println(new String(bs));
    }

    /**
     * 监听类，接收来自zookeeper的回调
     * @author Administrator
     *
     */
    static class DemoWatcher implements Watcher {
        public void process(WatchedEvent event) {
            System.out.println("----------->");
            System.out.println("path:" + event.getPath());
            System.out.println("type:" + event.getType());
            System.out.println("stat:" + event.getState());
            System.out.println("<-----------");
        }
    }

    /**
     * 防止java程序未连上zookeeper的服务器而往下执行，需等待zk的状态码
     * @param zooKeeper
     */
    public static void waitUntilConnected(ZooKeeper zooKeeper) {
        CountDownLatch connectedLatch = new CountDownLatch(1);
        Watcher watcher = new ConnectedWatcher(connectedLatch);
        zooKeeper.register(watcher);
        if (States.CONNECTING == zooKeeper.getState()) {
            try {
                connectedLatch.await();
            } catch (InterruptedException e) {
                throw new IllegalStateException(e);
            }
        }
    }

    static class ConnectedWatcher implements Watcher {
        private CountDownLatch connectedLatch;

        ConnectedWatcher(CountDownLatch connectedLatch) {
            this.connectedLatch = connectedLatch;
        }

        public void process(WatchedEvent event) {
            if (event.getState() == KeeperState.SyncConnected) {
                connectedLatch.countDown();
            }
        }
    }
}