1 Ngix 和 dubbo的负载均衡的区别？

Ngix负责前端的负载均衡，zookeeper负责后台的dubbo的rpc的集群的负载均衡

2 代码实现

监听者

import java.io.IOException; import org.apache.log4j.Logger;import org.apache.zookeeper.CreateMode;import org.apache.zookeeper.KeeperException;import org.apache.zookeeper.WatchedEvent;import org.apache.zookeeper.Watcher;import org.apache.zookeeper.ZooDefs.Ids;import org.apache.zookeeper.ZooKeeper;import org.apache.zookeeper.data.Stat; public class WatchMore{ /** * Logger for this class */ private static final Logger logger = Logger.getLogger(WatchMore.class); // 定义常量 private static final String CONNECTSTRING = "192.168.10.167:2181"; private static final int SESSION_TIMEOUT = 50 * 1000; private static final String PATH = "/atguigu"; // 定义实例变量 private ZooKeeper zk = null; private String oldValue = ""; public ZooKeeper startZK() throws IOException { return new ZooKeeper(CONNECTSTRING, SESSION_TIMEOUT, new Watcher() { @Override public void process(WatchedEvent event) { } }); } public void createZNode(String nodePath, String nodeValue) throws KeeperException, InterruptedException { zk.create(nodePath, nodeValue.getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT); } public String getZNode(String nodePath) throws KeeperException, InterruptedException { String result = ""; byte[] byteArray = zk.getData(nodePath, new Watcher() { @Override public void process(WatchedEvent event) { try { triggerValue(nodePath); } catch (KeeperException | InterruptedException e) { e.printStackTrace(); } } }, new Stat()); result = new String(byteArray); oldValue = result; return result; } public boolean triggerValue(String nodePath) throws KeeperException, InterruptedException { String result = ""; byte[] byteArray = zk.getData(nodePath, new Watcher() { @Override public void process(WatchedEvent event) { try { triggerValue(nodePath); } catch (KeeperException | InterruptedException e) { e.printStackTrace(); } } }, new Stat()); result = new String(byteArray); String newValue = result; if (oldValue.equals(newValue)) { logger.info("**************no change****************"); return false; } else { logger.info("**************oldValue:" + oldValue + "\t newValue: " + newValue); oldValue = newValue; return true; } } public static void main(String[] args) throws IOException, KeeperException, InterruptedException { WatchMore myWatch = new WatchMore(); // 1 获得zk实例 myWatch.setZk(myWatch.startZK()); if (myWatch.getZk().exists(PATH, false) == null) { String initValue = "AAA"; myWatch.createZNode(PATH, initValue); logger.info("***************main: " + myWatch.getZNode(PATH)); Thread.sleep(Long.MAX_VALUE); }else { logger.info("***************have node*******"); } } // setter------getter public ZooKeeper getZk() { return zk; } public void setZk(ZooKeeper zk) { this.zk = zk; } public String getOldValue() { return oldValue; } public void setOldValue(String oldValue) { this.oldValue = oldValue; } }

3 实现负载均衡的服务

import java.io.IOException;import java.util.ArrayList;import java.util.List; import org.apache.log4j.Logger;import org.apache.zookeeper.KeeperException;import org.apache.zookeeper.WatchedEvent;import org.apache.zookeeper.Watcher;import org.apache.zookeeper.ZooKeeper;import org.apache.zookeeper.data.Stat;import com.atguigu.zk.watch.WatchMore;public class BalanceTest { /** * Logger for this class */ private static final Logger logger = Logger.getLogger(WatchMore.class); // 定义常量 private static final String CONNECTSTRING = "192.168.31.167:2181"; private static final int SESSION_TIMEOUT = 50 * 1000; private static final String PATH = "/atcunzi"; private static final String SUB_PREFIX = "sub"; // 定义实例变量 private ZooKeeper zk = null; private List<String> serviceLists = new ArrayList<String>(); // sub1,.....sub5 // 用来收集可用服务的 private int subCount = 5; // 可用服务个数 private int currentServiceNum = 0; // 当前请求序号 // 初始化zookeepr，并获取服务的集合 public ZooKeeper startZK() throws IOException { return new ZooKeeper(CONNECTSTRING, SESSION_TIMEOUT,new Watcher() { @Override public void process(WatchedEvent event) { try { serviceLists = zk.getChildren(PATH,true); }catch (KeeperException | InterruptedException e) { e.printStackTrace(); } } }); } // 处理轮询算法逻辑 重要的是怎么能让服务 轮询 public String dealRquest() throws KeeperException, InterruptedException { currentServiceNum = currentServiceNum + 1; for (int i = currentServiceNum; i <=subCount; i++) { if(serviceLists.contains(SUB_PREFIX+currentServiceNum)) { return new String(zk.getData(PATH+"/"+SUB_PREFIX+currentServiceNum,false,new Stat())); }else{ currentServiceNum = currentServiceNum + 1; } } //重要的是怎么能让服务 轮询 1 3 5 currentServiceNum = 6 for (int i = 1; i <=subCount; i++) { if(serviceLists.contains(SUB_PREFIX+i)) { currentServiceNum = i; return new String(zk.getData(PATH+"/"+SUB_PREFIX+currentServiceNum,false,new Stat())); } } return "no subNode~~~~~"; } public static void main(String[] args) throws IOException, InterruptedException { BalanceTest test = new BalanceTest(); test.setZk(test.startZK()); Thread.sleep(3000); String result = null; for (int i = 1; i <=15; i++) { try { result = test.dealRquest(); logger.info("*********customerID: "+i+"\t currentWindows:"+test.currentServiceNum+"\t"+result); Thread.sleep(2000); } catch (KeeperException | InterruptedException e) { e.printStackTrace(); } } } ///----setter=-=getter public ZooKeeper getZk() { return zk; } public void setZk(ZooKeeper zk) { this.zk = zk; }}

4 总结

负载均衡可以看成一个银行，请求看成是顾客，后台服务看成是银行柜台，大堂经理可以看成zookeeper

服务启动的时候，需要先准备各个银行柜台都准备好，当顾客来到时候，可以 通过大堂经理的指引，去到相应的柜台进行柜台处理。

难点：当一个柜台暂停服务时候，大唐经理怎么知道的，并且怎么分发处理，并且服务怎么轮询的？

5 maven配置

<project xmlns="" xmlns:xsi="" xsi:schemaLocation=" "> <modelVersion>4.0.0</modelVersion> <groupId>com.atguigu.zk1014</groupId> <artifactId>zk1014</artifactId> <version>0.0.1-SNAPSHOT</version> <packaging>jar</packaging> <name>zk1014</name> <url>;/url> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> </properties> <dependencies> <!-- --> <dependency> <groupId>com.101tec</groupId> <artifactId>zkclient</artifactId> <version>0.10</version> </dependency> <!-- --> <dependency> <groupId>org.apache.zookeeper</groupId> <artifactId>zookeeper</artifactId> <version>3.4.9</version> </dependency> <dependency> <groupId>log4j</groupId> <artifactId>log4j</artifactId> <version>1.2.17</version> </dependency> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>4.9</version> <scope>test</scope> </dependency> </dependencies></project>