java 获取 zookeeper 集群没个节点状态 zookeeper查看集群

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信息流星 2024-01-27 23:38:29

文章标签 apache zookeeper 客户端 文章分类 Java 后端开发

启动Zookeeper集群：bin/zkServer.sh start

查看当前服务器为集群中的哪个角色：bin/zkServer.sh status

一、客户端操作

java 获取 zookeeper 集群没个节点状态 zookeeper查看集群_客户端

1.启动客户端：bin/zkCli.sh

2．显示所有操作命令 help
3．查看当前 znode 中所包含的内容 ls /
4．查看当前节点详细数据：ls2 /

5.创建普通节点：create /sanguo "jinlian"

create /sanguo/shuguo liubei

6.获取节点的值：get /sanguo

7.创建短暂节点：create -e /sanguo/wuguo "zhaoyu"

（1）在当前会话可见 ls /sanguo/wuguo 有结果

（2）退出客户端，再次启动客户端， ls /sanguo/wuguo 发现没结果，节点已被删除。

8.创建带序号的节点：create /sanguo/weiguo "caocao"

create /sanguo/weiguo "caocao"

如果原来没有序号节点，序号从 0 开始依次递增。如果原节点下已有 2 个节点，则再排序时从 2 开始，以此类推

9.修改节点的值： set /sanguo/weiguo "simayi"

10节点的值变化监听：在第一台主机上通过客户端注册对/sanguo节点的数据变化监听：get /sanguo watch

在第二台主机上修改/sanguo节点的数据

在第一台主机收到数据变化的监听

WatchedEvent state:SyncConnected type:NodeDataChanged path:/sanguo

11.节点的子节点变化监听（路径变化）

在第一台主机上通过客户端注册对/sanguo节点的路径变化监听：ls /sanguo watch

在第二台主机上增加/sanguo下的一个子节点:create /sanguo/xixi “haha”

在第一台主机收到数据变化的监听

WatchedEvent state:SyncConnected type:NodeChildrenChanged path:/sanguo

12.删除节点 delete /sanguo/xixi

13.递归删除节点：rmr /sanguo/shuguo

14.查看节点的状态 stat /sanguo

二、Java原生API调用

1.创建一个Maven工程

2.添加pom文件

<?xml version="1.0" encoding="utf-8"?>

<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>  
  <!-- https://mvnrepository.com/artifact/org.apache.zookeeper/zook eeper -->  
  <dependency> 
    <groupId>org.apache.zookeeper</groupId>  
    <artifactId>zookeeper</artifactId>  
    <version>3.4.10</version> 
  </dependency> 
</dependencies>

3.log4j.properties

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/spring.log 

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

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

4.创建Zookeeper客户端

private static String connectString = "hadoop102:2181,hadoop103:2181,hadoop104:2181";
	private static int sessionTimeout = 2000;
	private ZooKeeper zkClient = null;
  
	@Before
	public void init() throws Exception {
  
	zkClient = new ZooKeeper(connectString, sessionTimeout, new Watcher() {
			@Override
			public void process(WatchedEvent event) {
				// 收到事件通知后的回调函数（用户的业务逻辑）
				System.out.println(event.getType() + "--" + event.getPath());
  
			}
		});
	}

5.创建一个节点

// 创建子节点
	@Test
	public void create() throws Exception {
		// 数据的增删改查
		// 参数1：要创建的节点的路径； 参数2：节点数据 ； 参数3：节点权限 ；参数4：节点的类型
		String nodeCreated = zkClient.create("/eclipse", "hello zk".getBytes(), Ids.OPEN_ACL_UNSAFE,CreateMode.PERSISTENT);
	}

6.获取子节点

// 获取子节点
	@Test
	public void getChildren() throws Exception {
		List children = zkClient.getChildren("/", true);
  
		for (String child : children) {
			System.out.println(child);
		}
  
		// 延时阻塞
		Thread.sleep(Long.MAX_VALUE);
	}

7.判断Znode是否存在

// 判断ZNode是否存在
	@Test
	public void exist() throws Exception {
		Stat stat = zkClient.exists("/eclipse", false);
  
		System.out.println(stat == null ? "not exist" : "exist");
	}

三、监听服务器节点动态上下线案例、

java 获取 zookeeper 集群没个节点状态 zookeeper查看集群_zookeeper_02

java 获取 zookeeper 集群没个节点状态 zookeeper查看集群_客户端_03

1.在集群上先创建一个server节点

create /servers "servers"

2.客户端做监听，服务端去注册一个临时节点

客户端代码

package com.atguigu.zkcase;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.ZooKeeper;
  
public class DistributeClient {
	private static String connectString = "hadoop102:2181,hadoop103:2181,hadoop104:2181";
	private static int sessionTimeout = 2000;
	private ZooKeeper zk = null;
	private String parentNode = "/servers";
  
	// 创建到zk的客户端连接
	public void getConnect() throws IOException {
		zk = new ZooKeeper(connectString, sessionTimeout, new Watcher() {
  
			@Override
			public void process(WatchedEvent event) {
  
				// 再次启动监听
				try {
					getServerList();
				} catch (Exception e) {
					e.printStackTrace();
				}
			}
		});
	}
  
	// 获取服务器列表信息
	public void getServerList() throws Exception {
  
		// 1获取服务器子节点信息，并且对父节点进行监听
		List children = zk.getChildren(parentNode, true);
  
        // 2存储服务器信息列表
		ArrayList servers = new ArrayList();
  
        // 3遍历所有节点，获取节点中的主机名称信息
		for (String child : children) {
			byte[] data = zk.getData(parentNode + "/" + child, false, null);
  
			servers.add(new String(data));
		}
  
        // 4打印服务器列表信息
		System.out.println(servers);
	}
  
	// 业务功能
	public void business() throws Exception {
		System.out.println("client is working ...");
Thread.sleep(Long.MAX_VALUE);
	}
  
	public static void main(String[] args) throws Exception {
  
		// 1获取zk连接
		DistributeClient client = new DistributeClient();
		client.getConnect();
  
		// 2获取servers的子节点信息，从中获取服务器信息列表
		client.getServerList();
  
		// 3业务进程启动
		client.business();
	}
}

服务端代码

package com.atguigu.zkcase;
  
import java.io.IOException;
import org.apache.zookeeper.CreateMode;
import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.ZooKeeper;
import org.apache.zookeeper.ZooDefs.Ids;
  
public class DistributeServer {
	private static String connectString = "hadoop102:2181,hadoop103:2181,hadoop104:2181";
	private static int sessionTimeout = 2000;
	private ZooKeeper zk = null;
	private String parentNode = "/servers";
  
	// 创建到zk的客户端连接
	public void getConnect() throws IOException{
  
		zk = new ZooKeeper(connectString, sessionTimeout, new Watcher() {
  
			@Override
			public void process(WatchedEvent event) {
  
			}
		});
	}
  
	// 注册服务器
	public void registServer(String hostname) throws Exception{
		String create = zk.create(parentNode + "/server", hostname.getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL_SEQUENTIAL);
  
		System.out.println(hostname +" is online "+ create);
	}
  
	// 业务功能
	public void business(String hostname) throws Exception{
		System.out.println(hostname+" is working ...");
  
		Thread.sleep(Long.MAX_VALUE);
	}
  
	public static void main(String[] args) throws Exception {
		// 1 获取zk连接
		DistributeServer server = new DistributeServer();
		server.getConnect();
  
		// 2 利用zk连接注册服务器信息
		server.registServer(args[0]);
  
		// 3 启动业务功能
		server.business(args[0]);
	}
}

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