ZooKeeper入门（二）：ZooKeeper常用命令介绍及使用Curator客户端实现分布式配置中心

# 使用本地默认2181端口连接
./bin/zkCli.sh 
# 连接远程zk服务，连接超时时间设置为3s
./bin/zkCli.sh -timeout 3000 -server <remoteIP>：2181
# 使用-waitforconnection选项连接远程zk服务
./bin/zkCli.sh -waitforconnection -timeout 3000 -server <remoteIP>:2181
# 使用自定义客户端配置属性文件连接远程zk服务
bin/zkCli.sh -client-configuration /path/to/client.properties

ZooKeeper -server host:port cmd args
	addauth scheme auth
	close
	config [-c] [-w] [-s]
	connect host:port
	create [-s] [-e] [-c] [-t ttl] path [data] [acl]
	delete [-v version] path
	deleteall path
	delquota [-n|-b|-N|-B] path
	get [-s] [-w] path
	getAcl [-s] path
	getAllChildrenNumber path
	getEphemerals path
	history
	listquota path
	ls [-s] [-w] [-R] path
	printwatches on|off
	quit
	reconfig [-s] [-v version] [[-file path] | [-members serverID=host:port1:port2;port3[,...]*]] | [-add serverId=host:port1:port2;port3[,...]]* [-remove serverId[,...]*]
	redo cmdno
	removewatches path [-c|-d|-a] [-l]
	set [-s] [-v version] path data
	setAcl [-s] [-v version] [-R] path acl
	setquota -n|-b|-N|-B val path
	stat [-w] path
	sync path
	version

[zk: localhost:2181(CONNECTED) 24] create /firstNode first
Created /firstNode

[zk: localhost:2181(CONNECTED) 26] create -s /firstNode second
Created /firstNode0000000007

[zk: localhost:2181(CONNECTED) 27] create -e /firstNode-ephemral  ephemeral 
Created /firstNode-ephemral

[zk: localhost:2181(CONNECTED) 28] get /firstNode
first

[zk: localhost:2181(CONNECTED) 30] get /firstNode0000000007
second

[zk: localhost:2181(CONNECTED) 31] set /firstNode first_update

[zk: localhost:2181(CONNECTED) 32] get /firstNode
first_update

[zk: localhost:2181(CONNECTED) 1] create /firstNode/child1 child1Data
Created /firstNode/child1
[zk: localhost:2181(CONNECTED) 2] create /firstNode/child2 child2Data
Created /firstNode/child2

[zk: localhost:2181(CONNECTED) 3] ls /firstNode
[child1, child2]

[zk: localhost:2181(CONNECTED) 4] stat /firstNode
cZxid = 0x10000003c
ctime = Mon Jul 18 01:01:18 CST 2022
mZxid = 0x10000003f
mtime = Mon Jul 18 01:22:45 CST 2022
pZxid = 0x100000045
cversion = 2
dataVersion = 1
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 12
numChildren = 2

delete /firstNode/child1
deleteall /firstNode

[zk: localhost:2181(CONNECTED) 5] delete /firstNode/child1
[zk: localhost:2181(CONNECTED) 6] deleteall /firstNode
[zk: localhost:2181(CONNECTED) 7] ls /firstNode
Node does not exist: /firstNode

[zk: localhost:2181(CONNECTED) 12] getAcl /firstNode
'world,'anyone
: cdrwa

[zk: localhost:2181(CONNECTED) 17] setAcl /persistent_node world:anyone:wa
[zk: localhost:2181(CONNECTED) 18] get /persistent_node
Insufficient permission : /persistent_node

[zk: localhost:2181(CONNECTED) 22] addauth digest zhangsan:123456
[zk: localhost:2181(CONNECTED) 23] setAcl /persistent_node auth:zhangsan:123456:rdwca

[zk: localhost:2181(CONNECTED) 24] getAcl /persistent_node
'diest,'zhangsan:jA/7JI9gsuLp0ZQn5J5dcnDQkHA=
: cdrwa
'digest,'zhangsan[zk:QalD+ltUgPWxu8Pd+gTLjlZ6aoY=
: cdrwa

/**
* 提供两个构造参数的创建CuratorFramework实例方法
* @param connectString 连接zookeeper服务的连接串
* @param retryPolicy 重试策略
*/
public static CuratorFramework newClient(String connectString, RetryPolicy retryPolicy) {
        return newClient(connectString, DEFAULT_SESSION_TIMEOUT_MS, DEFAULT_CONNECTION_TIMEOUT_MS, retryPolicy);
    }
/**
* 提供四个构造参数的创建CuratorFramework实例方法
* @param connectString 连接zookeeper服务的连接串
* @param sessionTimeoutMs会话超时时间（单位：ms）
* @param connectionTimeoutMs 连接超时时间 （单位：ms）
*/
public static CuratorFramework newClient(String connectString, int sessionTimeoutMs, int connectionTimeoutMs, RetryPolicy retryPolicy) {
        return builder().connectString(connectString).sessionTimeoutMs(sessionTimeoutMs).connectionTimeoutMs(connectionTimeoutMs).retryPolicy(retryPolicy).build();
    }

/**
* 构建器方法,该方法返回一个CuratorFramework实例的构建器
* 通过静态内部类Builder的build方法创建CuratorFramework实例
*/
public  static CuratorFrameworkFactory.Builder builder() {
        return new CuratorFrameworkFactory.Builder();
    }
public  static  class Builder {
    public CuratorFramework build() {
            return new CuratorFrameworkImpl(this);
        }
}

// 创建持久节点
client.create().forPath("/head", new byte[0]);
// 删除节点
client.delete().inBackground().forPath("/head");
// 创建临时有序节点
client.create().withMode(CreateMode.EPHEMERAL_SEQUENTIAL).forPath("/head/child", new byte[0]);
// 设置监听器
client.getData().watched().inBackground().forPath("/test");

 void eventReceived(CuratorFramework client, CuratorEvent event) throws Exception;

  CuratorFramework    client = CuratorFrameworkFactory.builder().namespace("MyApp") ... build();
 ...
client.create().forPath("/test", data);
// znode 实际会写到 "/MyApp/test" 路径下

 <dependency>
			<groupId>org.apache.curator</groupId>
			<artifactId>curator-framework</artifactId>
			<version>4.0.0</version>
		</dependency>
		<dependency>
			<groupId>org.apache.curator</groupId>
			<artifactId>curator-recipes</artifactId>
			<version>4.0.0</version>
		</dependency> 

  zookeeper.connect.url=119.29.117.19:2181,119.29.117.19:2182,119.29.117.19:2183

  package org.sang.config;

import org.apache.curator.framework.CuratorFramework;
import org.apache.curator.framework.CuratorFrameworkFactory;
import org.apache.curator.framework.recipes.cache.TreeCache;
import org.apache.curator.retry.RetryOneTime;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

import javax.annotation.PostConstruct;
import java.util.List;
import java.util.Properties;

@Component
public  class ZooKeeperConfig {

    private static final Logger logger = LoggerFactory.getLogger(ZooKeeperConfig.class);
    @Value("${zookeeper.connect.url}")
    private String zooKeeperConnectUrl;

    private Properties configProperties = new Properties();

    public String getProperty(String key){
        return configProperties.getProperty(key);
    }

    // 项目启动后自动拉取ZooKeeper中路径为"/config"的节点下的子节点配置项
    @PostConstruct
    public void init() throws Exception {
        // 连接zookeeper
        CuratorFramework zkClient = CuratorFrameworkFactory.newClient(zooKeeperConnectUrl, new RetryOneTime(1000));
        zkClient.start();
        List<String> configNames = zkClient.getChildren().forPath("/config");
        for(String key: configNames){
            // 获取每个路径下的值(即配置值)
            byte[] value = zkClient.getData().forPath("/config/"+key);
            configProperties.put(key, new String(value, "UTF-8"));
        }
        //保证实时性，利用zk的watch机制
        TreeCache treeCache = new TreeCache(zkClient, "/config");
        treeCache.start();
        // 创建监听器
        treeCache.getListenable().addListener((curatorFramework, treeCacheEvent) -> {
            switch (treeCacheEvent.getType()){
                case NODE_UPDATED:
                    // 获取变更节点的路径名
                    String configName = treeCacheEvent.getData().getPath().replace("/config/", "");
                    // 监听到zk的zNode发生了数据变更
                    logger.info(configName + "的值发生了更新, 更新后的值为：" + new String(treeCacheEvent.getData().getData(), "UTF-8"));
                    // 获取变更的值
                    String configValue = new String(treeCacheEvent.getData().getData(), "UTF-8");
                    configProperties.put(configName, configValue);
                    break;
                default:
                    break;
            }
        });
    }

}

  [zk: localhost:2181(CONNECTED) 1] create /config/key1 valu1
Created /config/key1
[zk: localhost:2181(CONNECTED) 2] create /config/key2 valu2
Created /config/key2
[zk: localhost:2181(CONNECTED) 3] create /config/key3 value3
Created /config/key3

  2022-07-21 16:30:54.450  INFO 8856 --- [tor-TreeCache-0] org.sang.config.ZooKeeperConfig          : key1的值发生了更新, 更新后的值为：eurekaService
2022-07-21 16:32:59.019  INFO 8856 --- [tor-TreeCache-0] org.sang.config.ZooKeeperConfig          : key2的值发生了更新, 更新后的值为：consulService
2022-07-21 16:34:38.300  INFO 8856 --- [tor-TreeCache-0] org.sang.config.ZooKeeperConfig          : key3的值发生了更新, 更新后的值为：nacosService