Zookeeper輪詢算法以及與Dubbo的整合

首先介紹Zookeeper的命名服務

命名服務，客戶端能夠根據指定節點的名字來獲取資源或者服務地址，然後進行下一步操作

Zookeeper集羣的負載均衡

可使用Nginx（或Haproxy） +keepalived 來實現Zookeeper集羣的負載均衡

單個Zookeeper 中znode的輪詢

java代碼實現輪詢:

當節點服務關閉,不會影響其他節點服務的使用

/**
 * 
 * 模擬兩秒一個請求,分配到 /bank/下的bk1,bk2,bk3,bk4,bk5
 * 實際不能這麼寫 = = 這只是一個測試,一個思想,具體線程安全等問題沒有實現
 * @author start_lie
 *
 */
public class MyZookeeper {
	private final static Logger log = Logger.getLogger(MyZookeeper.class);
	private static ZooKeeper zk=null;
	private final static String CONNECT_STRING="192.168.83.128:2991";
	private final static int SESSION_TIMEOUT=20*1000;
	private static int cutNum=1;
	private static int nextWindow=1;
	private static int totalWindow=5;
	static{
		try {
			zk=new ZooKeeper(CONNECT_STRING, SESSION_TIMEOUT, (even)->{});
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
	
	public void createZnode(String path,String data) throws KeeperException, InterruptedException {
		zk.create(path, data.getBytes(), Ids.OPEN_ACL_UNSAFE,CreateMode.PERSISTENT);
	}
	
	public String getZnode(String path) throws KeeperException, InterruptedException {
		byte[] result = zk.getData(path, new Watcher() {
			
			@Override
			public void process(WatchedEvent event) {
				// TODO Auto-generated method stub
				try {
					getZnode(path);
				} catch (Exception e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
			}
		}, new Stat());
		String dat = new String(result);
		log.info("now this node value is :"+dat);
		return dat;
	}
	public static String getZnode1(String path) throws KeeperException, InterruptedException {
		byte[] result = zk.getData(path, false, new Stat());
		String dat = new String(result);
		//log.info("now this node value is :"+dat);
		return dat;
	}
	public static String doRequest(String path) throws Exception {
		List<String> list = zk.getChildren(path, false);
		int sign=0;
		while(true) {
			sign++;
			if(list.contains("bk"+nextWindow)) {
				nextWindow++;
				return getZnode1(path+"/bk"+(nextWindow-1));
			}else {
				if(nextWindow>=totalWindow) {
					nextWindow=1;
				}else {
					nextWindow++;
				}
			}
			if(sign==totalWindow) {
				return "No useable Znode!";
			}
		}
	}
	public static void main(String[] args) throws  Exception {
//		MyZookeeper mzk = new MyZookeeper();
//		String path = "/myzoo";
//		String data = "zuishuai goodlook";
//		String result = mzk.getZnode(path);
//		if(result==null) {
//			mzk.createZnode(path, data);
//		}else {
//			log.info("i have this node");
//		}
//		Thread.sleep(Long.MAX_VALUE);
		while(true) {
			String reault = doRequest("/bank");
			System.out.println("Curstom : "+(cutNum++)+"  result :"+reault);
			Thread.sleep(2000);
			
		}
		
	}
}

與Dubbo整合

web.xml中整合spring

pom.xml加依賴

<dependency>
     <groupId>org.springframework</groupId>
     <artifactId>spring-webmvc</artifactId>
     <version>4.1.3.RELEASE</version>
    </dependency>
    <dependency>
     <groupId>com.alibaba</groupId>
     <artifactId>dubbo</artifactId>
     <version>2.5.7</version>
     <exclusions>
       <exclusion>
         <!-- 排除傳遞spring依賴 -->
         <artifactId>spring</artifactId>
         <groupId>org.springframework</groupId>
       </exclusion>
     </exclusions>
    </dependency>
    <dependency>
     <groupId>org.apache.zookeeper</groupId>
     <artifactId>zookeeper</artifactId>
     <version>3.3.3</version>
    </dependency>
    <dependency>
     <groupId>com.github.sgroschupf</groupId>
     <artifactId>zkclient</artifactId>
     <version>0.1</version>
   </dependency>

在resourse下新建文件夾dubbo,在裏面新建dubbo.xml文件,內容(設置服務實現類,並將其接口暴露):

<beans xmlns="http://www.springframework.org/schema/beans"
  xmlns:context="http://www.springframework.org/schema/context" xmlns:p="http://www.springframework.org/schema/p"
  xmlns:aop="http://www.springframework.org/schema/aop" xmlns:tx="http://www.springframework.org/schema/tx"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:dubbo="http://code.alibabatech.com/schema/dubbo"
  xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
  http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd
  http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.0.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.0.xsd
  http://code.alibabatech.com/schema/dubbo http://code.alibabatech.com/schema/dubbo/dubbo.xsd">
 
  <!-- 提供方應用信息，用於計算依賴關係 -->
  <dubbo:application name="dubboProvider" />
  <!-- 這裏使用的註冊中心是zookeeper,請換成自己的IP地址 -->
  <dubbo:registry address="zookeeper://192.168.1.167:2181" client="zkclient" />
  <!-- 用dubbo協議在20880端口暴露服務 -->
  <dubbo:protocol name="dubbo" port="20880"/>
  
  <!-- 將該接口暴露到dubbo中 -->
  <dubbo:service  ref="bookServiceImpl" interface="com.test.dubbo.service.BookService"/>
  <!-- 將具體的實現類加入到Spring容器中 -->
  <bean id="bookServiceImpl" class="com.test.dubbo.BookServiceImpl" />
</beans>
 

消費者服務中resourse下建立dubbo/dubbo.xml :

<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:context="http://www.springframework.org/schema/context" xmlns:p="http://www.springframework.org/schema/p"
	xmlns:aop="http://www.springframework.org/schema/aop" xmlns:tx="http://www.springframework.org/schema/tx"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:dubbo="http://code.alibabatech.com/schema/dubbo"
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
  http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd
  http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.0.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.0.xsd
  http://code.alibabatech.com/schema/dubbo http://code.alibabatech.com/schema/dubbo/dubbo.xsd">

	<!-- 提供方應用信息 -->
	<dubbo:application name="dubboConsumer" />
	<!--註冊中心是zookeeper -->
	<dubbo:registry address="zookeeper://192.168.83.128:2991"	client="zkclient" />


	<!-- 從註冊中心中查找服務 -->
	<dubbo:reference id="bookService"	interface="com.test.service.BookService" />

</beans>

 用spring自動注入該service就可以調用了

註冊多節點+輪詢算法可以實現軟負載均衡