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第3章 Zookeeper 客户端API操作

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3.3 客户端API操作

前提:保证hadoop102、hadoop103、hadoop104服务器上Zookeeper集群服务端启动。

zk.sh start

3.3.1 IDEA环境搭建

1)创建一个工程:zookeeper

2)添加pom文件

<dependencies>
	<dependency>
		<groupId>junit</groupId>
		<artifactId>junit</artifactId>
		<version>RELEASE</version>
	</dependency>

	<dependency>
		<groupId>org.apache.logging.log4j</groupId>
		<artifactId>log4j-core</artifactId>
		<version>2.8.2</version>
	</dependency>

	<dependency>
		<groupId>org.apache.zookeeper</groupId>
		<artifactId>zookeeper</artifactId>
		<version>3.5.7</version>
	</dependency>
</dependencies>

3)拷贝log4j.properties文件到项目根目录

需要在项目的src/main/resources目录下,新建一个文件,命名为“log4j.properties”,在文件中填入。

log4j.rootLogger=INFO, stdout  

log4j.appender.stdout=org.apache.log4j.ConsoleAppender  

log4j.appender.stdout.layout=org.apache.log4j.PatternLayout  

log4j.appender.stdout.layout.ConversionPattern=%d %p [%c] - %m%n  

log4j.appender.logfile=org.apache.log4j.FileAppender  

log4j.appender.logfile.File=target/log4j.log  

log4j.appender.logfile.layout=org.apache.log4j.PatternLayout  

log4j.appender.logfile.layout.ConversionPattern=%d %p [%c] - %m%n  

4)创建包名com.wolffy.zookeeper

5)创建类名称zkClient

3.3.2 创建ZooKeeper客户端

public class ZkClient {

    private String connectString;
    private int sessionTimeout;
    private ZooKeeper zkClient;

    /
     * 获取客户端对象
     *
     * @throws IOException
     */
    @Before
    public void init() throws IOException {

        connectString = "hadoop102:2181,hadoop103:2181,hadoop104:2181";
        int sessionTimeout = 10000;

        //参数解读 1集群连接字符串  2连接超时时间 单位:毫秒  3当前客户端默认的监控器
        zkClient = new ZooKeeper(connectString, sessionTimeout, new Watcher() {
            @Override
            public void process(WatchedEvent event) {
            }
        });
    }

    /
     * 关闭客户端对象
     * @throws InterruptedException
     */
    @After
    public void close() throws InterruptedException {
        zkClient.close();
    }
}

3.3.3 获取子节点列表,不监听

/**
 * 获取子节点列表,不监听
 *
 * @throws IOException
 * @throws KeeperException
 * @throws InterruptedException
 */
@Test
public void ls() throws IOException, KeeperException, InterruptedException {
    //用客户端对象做各种操作
    List<String> children = zkClient.getChildren("/", false);
    System.out.println(children);
}

3.3.4 获取子节点列表,并监听

/**
 * 获取子节点列表,并监听
 *
 * @throws KeeperException
 * @throws InterruptedException
 */
@Test
public void lsAndWatch() throws KeeperException, InterruptedException {
    List<String> children = zkClient.getChildren("/", new Watcher() {
        @Override
        public void process(WatchedEvent event) {
            System.out.println(event);
        }
    });
    System.out.println(children);

    //因为设置了监听,所以当前线程不能结束
    Thread.sleep(Long.MAX_VALUE);
}

3.3.5 创建子节点

/**
 * 创建子节点
 *
 * @throws KeeperException
 * @throws InterruptedException
 */
@Test
public void create() throws KeeperException, InterruptedException {
    //参数解读 1节点路径  2节点存储的数据
    //3节点的权限(使用Ids选个OPEN即可) 4节点类型 短暂 持久 短暂带序号 持久带序号
    String path = zkClient.create("/wolffy", "QQ:2902839937".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);

    //创建临时节点
    //String path = zkClient.create("/wolffy2", "QQ:2902839937".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL);

    System.out.println(path);

    //创建临时节点的话,需要线程阻塞
    //Thread.sleep(10000);
}

3.3.6 判断Znode是否存在

/**
 * 判断Znode是否存在
 *
 * @throws Exception
 */
@Test
public void exist() throws Exception {

    Stat stat = zkClient.exists("/wolffy", false);

    System.out.println(stat == null ? "not exist" : "exist");
}

3.3.7 获取子节点存储的数据,不监听

/**
 * 获取子节点存储的数据,不监听
 *
 * @throws KeeperException
 * @throws InterruptedException
 */
@Test
public void get() throws KeeperException, InterruptedException {
    //判断节点是否存在
    Stat stat = zkClient.exists("/wolffy", false);
    if (stat == null) {
        System.out.println("节点不存在...");
        return;
    }

    byte[] data = zkClient.getData("/wolffy", false, stat);
    System.out.println(new String(data));
}

3.3.8 获取子节点存储的数据,并监听

/**
 * 获取子节点存储的数据,并监听
 *
 * @throws KeeperException
 * @throws InterruptedException
 */
@Test
public void getAndWatch() throws KeeperException, InterruptedException {
    //判断节点是否存在
    Stat stat = zkClient.exists("/wolffy", false);
    if (stat == null) {
        System.out.println("节点不存在...");
        return;
    }

    byte[] data = zkClient.getData("/wolffy", new Watcher() {
        @Override
        public void process(WatchedEvent event) {
            System.out.println(event);
        }
    }, stat);
    System.out.println(new String(data));
    //线程阻塞
    Thread.sleep(Long.MAX_VALUE);
}

3.3.9 设置节点的值

/**
 * 设置节点的值
 *
 * @throws KeeperException
 * @throws InterruptedException
 */
@Test
public void set() throws KeeperException, InterruptedException {
    //判断节点是否存在
    Stat stat = zkClient.exists("/wolffy", false);
    if (stat == null) {
        System.out.println("节点不存在...");
        return;
    }
    //参数解读 1节点路径 2节点的值 3版本号
    zkClient.setData("/wolffy", "wolffy".getBytes(), stat.getVersion());
}

3.3.10 删除空节点

/**
 * 删除空节点
 *
 * @throws KeeperException
 * @throws InterruptedException
 */
@Test
public void delete() throws KeeperException, InterruptedException {
    //判断节点是否存在
    Stat stat = zkClient.exists("/small", false);
    if (stat == null) {
        System.out.println("节点不存在...");
        return;
    }
    zkClient.delete("/small", stat.getVersion());
}

3.3.11 删除非空节点,递归实现

/**
 * 封装一个方法,方便递归调用
 */
public void deleteAll(String path, ZooKeeper zk) throws KeeperException, InterruptedException {
    //判断节点是否存在
    Stat stat = zkClient.exists(path, false);
    if (stat == null) {
        System.out.println("节点不存在...");
        return;
    }
    //先获取当前传入节点下的所有子节点
    List<String> children = zk.getChildren(path, false);
    if (children.isEmpty()) {
        //说明传入的节点没有子节点,可以直接删除
        zk.delete(path, stat.getVersion());
    } else {
        //如果传入的节点有子节点,循环所有子节点
        for (String child : children) {
            //删除子节点,但是不知道子节点下面还有没有子节点,所以递归调用
            deleteAll(path + "/" + child, zk);
        }
        //删除完所有子节点以后,记得删除传入的节点
        zk.delete(path, stat.getVersion());
    }
}

//测试deleteAll
@Test
public void testDeleteAll() throws KeeperException, InterruptedException {
    deleteAll("/wolffy", zkClient);
}

标签:stat,Zookeeper,InterruptedException,节点,API,zkClient,log4j,throws,客户端
来源: https://www.cnblogs.com/niuniu2022/p/16342404.html