Java - zookeeper 服務註冊發現

原創 textboy 2020-06-23 06:11

網上實際一些的案例嚴重缺乏，真心不易出此稿~~

1、zookeeper 服務註冊發現模型

流程：1）註冊，2）發現：監聽、負載均衡、故障檢測、變更通知，3）調用。


From http://blog.cloudera.com/blog/2014/03/zookeeper-resilience-at-pinterest/



From http://www.techweb.com.cn/network/hardware/2015-12-25/2246973.shtml



From http://docs.hortonworks.com/HDPDocuments/HDP2/HDP-2.3.2/bk_hadoop-ha/content/ha-hs2-service-discovery.html


2、單機代碼
虛擬機準備：1）啓動zookeeper，2）啓動多個服務（如ElasticSearch, Tomcat之類的），3）一個服務（如tomcat、elasticsearch）對應多個instance（如節點1、節點2）

流程：

1）準備：CuratorFramework（可選擇getClient或newClient方法），ServiceInstance；
2）註冊：ServiceDiscovery (註冊有兩種方式：registerService/thisInstance)；
3.1）負載均衡：ServiceProvider providerStrategy()
3.2）啓動監聽：ServiceProvider start()，一個provider對應一個服務；
4）通知：ServiceProvider getInstance()
5）調用: 有ip、port，想怎麼用就怎麼用吧~

import java.io.Closeable;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.UUID;

import org.apache.curator.RetryPolicy;
import org.apache.curator.framework.CuratorFramework;
import org.apache.curator.framework.CuratorFrameworkFactory;
import org.apache.curator.retry.ExponentialBackoffRetry;
import org.apache.curator.retry.RetryNTimes;
import org.apache.curator.utils.CloseableUtils;
import org.apache.curator.x.discovery.ServiceDiscovery;
import org.apache.curator.x.discovery.ServiceDiscoveryBuilder;
import org.apache.curator.x.discovery.ServiceInstance;
import org.apache.curator.x.discovery.ServiceProvider;
import org.apache.curator.x.discovery.UriSpec;
import org.apache.curator.x.discovery.details.JsonInstanceSerializer;
import org.apache.curator.x.discovery.strategies.RandomStrategy;
import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.ZooKeeper;

import com.google.common.collect.Lists;
import com.google.common.collect.Maps;

/*
 * http://www.techweb.com.cn/network/hardware/2015-12-25/2246973.shtml
 * http://blog.csdn.net/hxpjava1/article/details/8612228
 * http://www.tuicool.com/articles/F3Avue
 * http://www.bkjia.com/Javabc/879495.html
 * http://curator.apache.org/apidocs/index.html
 * http://blog.csdn.net/john_f_lau/article/details/50660195  *
 * http://search.maven.org/#search%7Cga%7C1%7Cg%3A%22org.apache.curator%22
 * share one CuratorFramework per ZooKeeper cluster
 * By default ServiceProvider uses Round-robin ProviderStrategy
 */
public class ZkTest01 {
	
	private static String basePath = "/es_path";
	private static List<Closeable> closeableList = Lists.newArrayList();
	
	// Register worker 1
	private static ServiceDiscovery<Void> registerInZookeeper(CuratorFramework client, 
			ServiceInstance<Void> instance) throws Exception {
		ServiceDiscovery<Void> serviceDiscovery;

		JsonInstanceSerializer<Void> serializer = new JsonInstanceSerializer<Void>(
				Void.class);
		//(3)
		serviceDiscovery = ServiceDiscoveryBuilder
				.builder(Void.class)
				.client(client)
				.serializer(serializer)
				.basePath(basePath)
				//.thisInstance(instance)  //註冊方式2
				.build();
		serviceDiscovery.start();
		//(4) cd <ZK_ROOT>/bin, ./zkCli.sh
		return serviceDiscovery;
	}
	
	// Register worker 2
		private static ServiceDiscovery<Void> registerInZookeeper2(CuratorFramework client, 
				ServiceInstance<Void> instance) throws Exception {
			ServiceDiscovery<Void> serviceDiscovery;

			JsonInstanceSerializer<Void> serializer = new JsonInstanceSerializer<Void>(
					Void.class);
			//(3)
			serviceDiscovery = ServiceDiscoveryBuilder
					.builder(Void.class)
					.client(client)
					.serializer(serializer)
					.basePath(basePath)
					//.thisInstance(instance)  //註冊方式2
					.build();
			serviceDiscovery.start();
			//(4) cd <ZK_ROOT>/bin, ./zkCli.sh
			return serviceDiscovery;
		}
	
	public static ServiceInstance<Void> getInstanceByName(ServiceDiscovery<Void> serviceDiscovery, 
			String serviceName) throws Exception {

		//(5) 非註冊方式，do not register in ZooKeeper, get instance from ServiceProvider
		ServiceProvider<Void> provider = serviceDiscovery.serviceProviderBuilder().
                serviceName(serviceName).
                providerStrategy(new RandomStrategy<Void>())
                .build();
        provider.start();
        closeableList.add(provider);
        return provider.getInstance();
    }
	
	public static synchronized void close(){
       for (Closeable closeable : closeableList) {
           CloseableUtils.closeQuietly(closeable);
       }
	}
	
	public static CuratorFramework getClient() {
		RetryPolicy retryPolicy = new ExponentialBackoffRetry(1000, 3);  
        CuratorFramework client = CuratorFrameworkFactory.builder()  
                .connectString("127.0.0.1:2181")  
                .sessionTimeoutMs(5000)  
                .connectionTimeoutMs(10000)  
                .retryPolicy(retryPolicy)  
                .namespace("text").build();
        client.start();
        return client;
	}
	
	public static void main(String[] args) throws Exception {
		// (1)
		CuratorFramework curatorFramework = CuratorFrameworkFactory.newClient("centos1:2182", new ExponentialBackoffRetry(1000, 1));
		curatorFramework.start();
		// (2)
		ServiceInstance<Void> instance1 = ServiceInstance.<Void>builder()
                .name("es1")
                .port(8080)
                .address("centos1")   //address不寫的話，會取本地ip
                //.payload(new Void(UUID.ra ndomUUID().toString(),"centos1",9200))
                .uriSpec(new UriSpec("{scheme}://{address}:{port}"))
                .build();
		ServiceDiscovery<Void> serviceDiscovery = registerInZookeeper2(curatorFramework, instance1);
		Iterator<String> ItrServices = serviceDiscovery.queryForNames().iterator();
		while(ItrServices.hasNext()) {
			System.out.println("ItrServices~~~" + ItrServices.next());
		}
		serviceDiscovery.registerService(instance1);  //註冊方式1
		Iterator ItrInstances = serviceDiscovery.queryForInstances("es1").iterator();
		while(ItrInstances.hasNext()) {
			System.out.println("ItrInstances~~~" + ItrInstances.next());
		}
		ServiceInstance<Void> instance_loopup = getInstanceByName(serviceDiscovery,"es1");
		System.out.println("address~~~" + instance_loopup.buildUriSpec());
		System.out.println("payload~~~" + instance_loopup.getPayload());
		//System.out.println("listenAddr~~~" + instance_loopup.getPayload().getListenAddress());
		
		close();
		CloseableUtils.closeQuietly(curatorFramework);
	}
	
	/*
	//register
	ServiceDiscovery = ServiceDiscoveryBuilder.builder.thisInstance(serviceInstance)
	start()

	//lookup (by load balancer)
	ServiceProvider = serviceDiscovery.serviceProviderBuilder().providerStrategy
	start()

	//invoke service

	-------
	CuratorFramework = CuratorFrameworkFactory.newClient / builder
	start()
	ServiceInstance = ServiceInstance.builder
	 */
}

3、單機負載均衡測試
多個服務是否按照負載均衡策略進行訪問，需要利用REST http方式進行測試。單機測試如下：

ZkTest02.java

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.net.InetSocketAddress;
import java.util.concurrent.Executors;

import org.apache.curator.framework.CuratorFramework;
import org.apache.curator.framework.CuratorFrameworkFactory;
import org.apache.curator.retry.ExponentialBackoffRetry;
import org.apache.curator.x.discovery.ServiceDiscovery;
import org.apache.curator.x.discovery.ServiceDiscoveryBuilder;
import org.apache.curator.x.discovery.ServiceInstance;
import org.apache.curator.x.discovery.ServiceProvider;
import org.apache.curator.x.discovery.UriSpec;
import org.apache.curator.x.discovery.details.JsonInstanceSerializer;
import org.apache.curator.x.discovery.strategies.RandomStrategy;
import org.apache.curator.x.discovery.strategies.RoundRobinStrategy;
import org.slf4j.LoggerFactory;

import com.sun.net.httpserver.HttpExchange;
import com.sun.net.httpserver.HttpHandler;
import com.sun.net.httpserver.HttpServer;
import com.sun.net.httpserver.spi.HttpServerProvider;


public class ZkTest02 {
	
	private static String basePath = "/es_path";
	private static ServiceDiscovery<Void> serviceDiscovery;
	private static ServiceProvider<Void> provider;
	
	public static void main(String[] args) throws IOException {
        httpserverService();
    }
	
	public static CuratorFramework getClient() {
		CuratorFramework curatorFramework = CuratorFrameworkFactory.newClient("centos1:2182", new ExponentialBackoffRetry(1000, 1));
		curatorFramework.start();
		return curatorFramework;
	}
	public static ServiceDiscovery<Void> getServiceDiscovery(CuratorFramework client) throws Exception {
		JsonInstanceSerializer<Void> serializer = new JsonInstanceSerializer<Void>(
				Void.class);
		ServiceDiscovery<Void> serviceDiscovery = ServiceDiscoveryBuilder
				.builder(Void.class)
				.client(client)
				.serializer(serializer)
				.basePath(basePath)
				.build();
		serviceDiscovery.start();
		return serviceDiscovery;
	}
	public static ServiceInstance<Void> getInstance1() throws Exception {
		ServiceInstance<Void> instance1 = ServiceInstance.<Void>builder()
                .name("es1")
                .port(8080)
                .address("centos1")
                .uriSpec(new UriSpec("http://centos1:8080"))
                .build();
		return instance1;
	}
	public static ServiceInstance<Void> getInstance2() throws Exception {
		ServiceInstance<Void> instance1 = ServiceInstance.<Void>builder()
                .name("es1")
                .port(9200)
                .address("centos1")
                .uriSpec(new UriSpec("http://centos1:9200"))
                .build();
		return instance1;
	}
	public static ServiceProvider<Void> serviceProvider(ServiceDiscovery<Void> serviceDiscovery, 
			String serviceName) throws Exception {
		ServiceProvider<Void> provider = serviceDiscovery.serviceProviderBuilder().
                serviceName(serviceName).
                providerStrategy(new RandomStrategy<Void>())
                .build();
        provider.start();
		return provider;
	}
	public static void process(String param) throws Exception {
		if (null == serviceDiscovery) {
    		LoggerFactory.getLogger("");
	    	serviceDiscovery = getServiceDiscovery(getClient());
	    	serviceDiscovery.registerService(getInstance1());
	    	serviceDiscovery.registerService(getInstance2());
    	}
		
    	if (null == provider) {
    		provider = serviceProvider(serviceDiscovery, param);
    	}
    	if (null != provider) {
	    	System.out.println("address~~~" + provider.getInstance().getAddress() + 
	    		", port~~~" + provider.getInstance().getPort());
//		    provider.close();
    	}
	}
	
	//啓動服務，監聽來自客戶端的請求
    public static void httpserverService() throws IOException {
        HttpServerProvider provider = HttpServerProvider.provider();
        HttpServer httpserver =provider.createHttpServer(new InetSocketAddress(8080), 100);//監聽端口6666,能同時接 受100個請求
        httpserver.createContext("/sc/es", new MyHttpHandler());
        //httpserver.setExecutor(null); //使用單線程
        httpserver.setExecutor(Executors.newFixedThreadPool(5));
        httpserver.start();
        System.out.println("server started");
    }
    //Http請求處理類
    static class MyHttpHandler implements HttpHandler {
        public void handle(HttpExchange httpExchange) throws IOException {
            String responseMsg = "ok";   //響應信息
            
            InputStream in = httpExchange.getRequestBody(); //獲得輸入流
            BufferedReader reader = new BufferedReader(new InputStreamReader(in));
            String temp = null;
            while((temp = reader.readLine()) != null) {
                System.out.println("client request:"+temp);
                try {
                	process(temp);
                } catch (Exception e) {
                	e.printStackTrace();
                }
            }
            
            httpExchange.sendResponseHeaders(200, responseMsg.length()); //設置響應頭屬性及響應信息的長度
            OutputStream out = httpExchange.getResponseBody();  //獲得輸出流
            out.write(responseMsg.getBytes());
            out.flush();
            httpExchange.close();
        }
    }
}

SpringRestTestClient.java （測試類）

import java.net.URI;

import org.springframework.web.client.RestClientException;
import org.springframework.web.client.RestTemplate;


public class SpringRestTestClient {
	public static final String REST_SERVICE_URI = "http://localhost:8080/sc";
//	public static final String REST_SERVICE_URI = "http://localhost:6666/myApp";
	
	private static void listAllUsers(){
		RestTemplate restTemplate = new RestTemplate();
		String param = "es1";
		try {
//			URI uri = restTemplate.postForLocation(REST_SERVICE_URI+"/es", jsonParam, String.class);
//			if (null != uri){
//				System.out.println("Location : "+uri.toASCIIString());
//			} else {
//				System.out.println("uri is null~");
//			}
			String result = restTemplate.postForObject(REST_SERVICE_URI+"/es", param, String.class);
			System.out.println("es-result~" + result);
		} catch (RestClientException e) {
			e.printStackTrace();
		}
	}
	
	public static void main(String[] args) {
		listAllUsers();
	}
}

先啓動ZkTest02，然後連續運行SpringRestTestClient 幾次。ZkTest02那邊的結果（sys out）： 

client request:es1
address~~~centos1, port~~~8080
client request:es1
address~~~centos1, port~~~9200
client request:es1
address~~~centos1, port~~~9200
client request:es1
address~~~centos1, port~~~8080
client request:es1
address~~~centos1, port~~~9200

4、Spring下負載均衡測試代碼

另外，也可以用Spring controller來做測試，不過遇到一些引用包的問題，應該與spring相關，由於前面的方法已經滿足PoC需求，暫時沒有再試下去，有興趣也可以參考以下代碼：

package com.test;

import org.apache.curator.framework.CuratorFramework;
import org.apache.curator.framework.CuratorFrameworkFactory;
import org.apache.curator.retry.ExponentialBackoffRetry;
import org.apache.curator.x.discovery.ServiceDiscovery;
import org.apache.curator.x.discovery.ServiceDiscoveryBuilder;
import org.apache.curator.x.discovery.ServiceInstance;
import org.apache.curator.x.discovery.ServiceProvider;
import org.apache.curator.x.discovery.UriSpec;
import org.apache.curator.x.discovery.details.JsonInstanceSerializer;
import org.apache.curator.x.discovery.strategies.RoundRobinStrategy;
import org.slf4j.LoggerFactory;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.util.UriComponentsBuilder;

@RestController
@RequestMapping("/zk")
public class ZkController {
	
	private static String basePath = "/es_path";
	private ServiceDiscovery<Void> serviceDiscovery;
	
	@RequestMapping(value = "/es", method = RequestMethod.POST)
    public String postUser(@RequestBody String param, UriComponentsBuilder ucBuilder) throws Exception {
    	if (null == serviceDiscovery) {
    		LoggerFactory.getLogger("");
	    	serviceDiscovery = getServiceDiscovery(getClient());
	    	serviceDiscovery.registerService(getInstance1());
	    	serviceDiscovery.registerService(getInstance2());
    	}
    	System.out.println("param~~~" + param);
    	ServiceProvider<Void> provider = serviceProvider(serviceDiscovery, param);
    	if (null != provider) {
	    	System.out.println("address~~~" + provider.getInstance().getAddress() + 
	    			", port~~~" + provider.getInstance().getPort());
	    	provider.close();
    	}
    	return param;
    }
	
	public CuratorFramework getClient() {
		CuratorFramework curatorFramework = CuratorFrameworkFactory.newClient("centos1:2182", new ExponentialBackoffRetry(1000, 1));
		curatorFramework.start();
		return curatorFramework;
	}
	public ServiceDiscovery<Void> getServiceDiscovery(CuratorFramework client) throws Exception {
		JsonInstanceSerializer<Void> serializer = new JsonInstanceSerializer<Void>(
				Void.class);
		ServiceDiscovery<Void> serviceDiscovery = ServiceDiscoveryBuilder
				.builder(Void.class)
				.client(client)
				.serializer(serializer)
				.basePath(basePath)
				.build();
		serviceDiscovery.start();
		return serviceDiscovery;
	}
	public ServiceInstance<Void> getInstance1() throws Exception {
		ServiceInstance<Void> instance1 = ServiceInstance.<Void>builder()
                .name("es1")
                .port(8080)
                .address("centos1")
                .uriSpec(new UriSpec("http://centos1:8080"))
                .build();
		return instance1;
	}
	public ServiceInstance<Void> getInstance2() throws Exception {
		ServiceInstance<Void> instance1 = ServiceInstance.<Void>builder()
                .name("es1")
                .port(9200)
                .address("centos1")
                .uriSpec(new UriSpec("http://centos1:9200"))
                .build();
		return instance1;
	}
	public ServiceProvider<Void> serviceProvider(ServiceDiscovery<Void> serviceDiscovery, 
			String serviceName) throws Exception {
		ServiceProvider<Void> provider = serviceDiscovery.serviceProviderBuilder().
                serviceName(serviceName).
                providerStrategy(new RoundRobinStrategy<Void>())
                .build();
        provider.start();
		return provider;
	}
}

上面的代碼只是基於zookeeer znode操作，對服務的監測還是需要自己實現的，比如一個provider - war程序服務，可以做一個REST接口出來進行監聽。



5、Q&A

Q: curator沒有現成的jar包
A: 上http://search.maven.org/
Q: Connection Timeout
A: 檢查zookeeper、服務的端口是否打開（如在centos，打開端口命令爲/sbin/iptables -I INPUT -p tcp --dport 2181 -j ACCEPT, /etc/init.d/iptables save, service iptables restart）
Q: base path找不到
A: 啓動zookeeper, 運行./zkCli.sh，使用zookeeer命令：ls / 看有沒有base_path，沒有就新建，如上面的例子，put /es_path/es1，ls /es_path/es1
Q: 在瀏覽器http訪問測試時，報不支持post錯誤或訪問爲get方式
A: post方式不能用瀏覽器http直接訪問測試，用代碼發送post請求或用postman來測試；
Q: 除了Curator，還有其它實現手段嗎
A: （1）zoologist（http://npm.taobao.org/package/zoologist，基於Curator REST接口以Node.js實現的包）；（2）Spring Cloud Zookeeper（http://cloud.spring.io/spring-cloud-zookeeper/spring-cloud-zookeeper.html，基於ZK和curator，spring boot上的實現）；（3）dubbo（http://dubbo.io/User+Guide-zh.htm，阿里框架，可以基於zookeeper和curator，並支持可視化交互monitor）。
Q: 有沒有其它Sample
A: （1）GitHub - curator-playground-master, curator-disco-master, disco-java；（2）Link: http://www.jianshu.com/p/c0ba6d62dd2e

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題目描述 輸入兩棵二叉樹A，B，判斷B是不是A的子結構。（ps：我們約定空樹不是任意一個樹的子結構） 思路：將B與A，A的左子樹，A的右子樹分別進行判斷，如果元素不相等返回 false ,運用遞歸直到A子樹爲空此時返回 false /*

浮煌 2020-07-08 11:43:28

java的二分查找源碼分析

前言：         之前用到二分查找的時候，都是自己手寫一個，雖然並不難，但是有的時候會忽略邊界條件，然後時間久了還會忘記，然後今天發現，Java其實已經實現了數組的二分查找，這裏就分析一下它的源碼   1:該方法在 Arrays.j

Cison chen 2020-07-08 11:07:50

android程序退出方案

在Android中退出程序比較麻煩，尤其是在多個Activity的程序中，在2.2之前可以採用如下代碼退出程序： Java代碼   ActivityManager am = (ActivityManager)getSystemS

shangmin1990 2020-07-08 11:03:08

啥時候用interface，啥時候用abstract類？ 就一句話

有初學者問interface和abstract類該怎樣選擇的問題，不扯麪試題那些，其實就一句話：   定義爲abstract類， 就是爲了定義較多的已實現方法好讓人繼承；繼承者就不用寫這麼多的實現了，可以直接拿來用； 定義爲interfa

_躬行_ 2020-07-08 10:35:56

#idea#一個Java工程頻繁被idea修改jdk版本問題

困擾。。。 發現創建maven工程師pom.xml文件中編譯版本寫爲1.7了，修改後再沒出現。 <properties> <project.build.sourceEncoding>UTF-8</project.build.sou

码农丁丁 2020-07-08 10:28:41

Head First Servlet/JSP 學習筆記(1)

     一次在逛書店的時候，偶然發現這本書的，爲之驚豔，所以買了回來給學生看。過了幾個月，自己閒下來，也準備系統看看，雖然做了兩個Struts, Spring, Hibernate的項目，覺得知識還不是很系統。 1. servlet沒有

fan_7 2020-07-08 09:39:41

【MAVEN】編譯報錯Perhaps you are running on a JRE rather than a JDK?

問題：mvn -e clean package 報錯log： [ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.1:co

弘毅密令 2020-07-08 09:18:10