监听ZK节点数据变化的几种方式
一、原生watch方式
1、引入依赖
<?xml version="1.0" encoding="UTF-8"?> <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <parent> <artifactId>Dubbo-Code</artifactId> <groupId>org.example</groupId> <version>1.0-SNAPSHOT</version> </parent> <modelVersion>4.0.0</modelVersion> <artifactId>zk-client</artifactId> <dependencies> <!-- Dubbo --> <dependency> <groupId>com.alibaba</groupId> <artifactId>dubbo</artifactId> </dependency> <dependency> <groupId>com.101tec</groupId> <artifactId>zkclient</artifactId> </dependency> <dependency> <groupId>com.alibaba</groupId> <artifactId>fastjson</artifactId> <version>1.2.75</version> </dependency> <dependency> <groupId>org.apache.zookeeper</groupId> <artifactId>zookeeper</artifactId> <version>3.5.6</version> <scope>compile</scope> </dependency> </dependencies> </project>
2、代码
package com.zk.demo; import org.apache.zookeeper.WatchedEvent; import org.apache.zookeeper.Watcher; import org.apache.zookeeper.ZooKeeper; import java.io.IOException; import java.util.LinkedHashMap; import java.util.List; import java.util.Map; public class Demo { static ZooKeeper zooKeeper; private static final String parentPath="/node"; //充当redis private static Map<String, Object> map = new LinkedHashMap<String, Object>(); static { try { zooKeeper = new ZooKeeper("192.168.20.93:2181", 2000, null); } catch (IOException e) { e.printStackTrace(); } } public static void main(String[] args) throws Exception { //获取节点数据,new Watcher监听节点数据变化 if (zooKeeper==null){ System.out.println("zk为空"); } Watcher watcher=new Watcher() { public void process(WatchedEvent event) { //event.getPath()获取节点路径,event.getType()获取节点变化类型 System.out.println(event.getPath()+"节点数据发生了变化:"+event.getType()); getChlidren(parentPath,this); } }; getChlidren(parentPath,watcher); Thread.sleep(Integer.MAX_VALUE); zooKeeper.close(); } /** * 递归获取节点信息 */ private static void getChlidren(String path,Watcher watcher) { try { if(path.equals(parentPath)) { byte[] data = zooKeeper.getData(path, watcher, null); String dataStr = new String(data); map.put(path, dataStr); System.out.println("[" + path + "]" + dataStr); } List<String> children = zooKeeper.getChildren(path, watcher); if(children.isEmpty() || children.size()==0){ return ; } for (String child : children) { String key = path+"/"+child; byte[] data1 = zooKeeper.getData(key, watcher, null); String dataStr1=new String(data1); map.put(path, dataStr1); System.out.println("["+key+"]"+dataStr1); getChlidren(key,watcher); } } catch ( Exception e) { System.err.println("获取节点信息异常"); System.out.println(e.getMessage()); } System.out.println("reloadCache : "+map.toString() ); } }
二、Curator
Curator应用场景-Watch监听机制(NodeCache,PathChildrenCache,TreeCache)
1、引用pom（注意Curator版本跟zk的版本有关系）
<?xml version="1.0" encoding="UTF-8"?> <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <parent> <artifactId>Dubbo-Code</artifactId> <groupId>org.example</groupId> <version>1.0-SNAPSHOT</version> </parent> <modelVersion>4.0.0</modelVersion> <artifactId>zk-client</artifactId> <dependencies> <!-- Dubbo --> <dependency> <groupId>com.alibaba</groupId> <artifactId>dubbo</artifactId> <version> 2.6.8</version> </dependency> <dependency> <groupId>com.101tec</groupId> <artifactId>zkclient</artifactId> <version> 0.11</version> </dependency> <dependency> <groupId>com.alibaba</groupId> <artifactId>fastjson</artifactId> <version>1.2.75</version> </dependency> <dependency> <groupId>org.apache.zookeeper</groupId> <artifactId>zookeeper</artifactId> <version>3.5.6</version> </dependency> <dependency> <groupId>org.apache.curator</groupId> <artifactId>curator-framework</artifactId> <version>2.12.0</version> </dependency> <dependency> <groupId>org.apache.curator</groupId> <artifactId>curator-recipes</artifactId> <version>2.12.0</version> </dependency> </dependencies> </project>
2、TreeCache案例代码
package com.zk.cache; import org.apache.curator.framework.CuratorFramework; import org.apache.curator.framework.CuratorFrameworkFactory; import org.apache.curator.framework.recipes.cache.TreeCache; import org.apache.curator.framework.recipes.cache.TreeCacheEvent; import org.apache.curator.framework.recipes.cache.TreeCacheListener; import org.apache.curator.retry.ExponentialBackoffRetry; import org.apache.zookeeper.data.Stat; public class TreeCacheListen { public static void main(String[] args) throws Exception { CuratorFramework zkClient = getZkClient(); String path = "/node"; byte[] initData = "initData".getBytes(); Stat stat = zkClient.checkExists().forPath(path); if (stat == null) { //创建节点用于测试 zkClient.create().forPath(path, initData); } TreeCache treeCache = new TreeCache(zkClient, path); //调用start方法开始监听 treeCache.start(); //添加TreeCacheListener监听器 treeCache.getListenable().addListener(new TreeCacheListener() { @Override public void childEvent(CuratorFramework client, TreeCacheEvent event) throws Exception { System.out.println("监听到节点数据变化，类型："+event.getType()+",路径："+event.getData().getPath()+",数据："+new String(event.getData().getData())); } }); Thread.sleep(1000); //更新父节点数据 zkClient.setData().forPath(path, "222".getBytes()); Thread.sleep(1000); String childNodePath = path + "/child"; //创建子节点 zkClient.create().forPath(childNodePath, "111".getBytes()); Thread.sleep(1000); //更新子节点 zkClient.setData().forPath(childNodePath, "222".getBytes()); Thread.sleep(1000); //删除子节点 zkClient.delete().forPath(childNodePath); Thread.sleep(Integer.MAX_VALUE); } private static CuratorFramework getZkClient() { String zkServerAddress = "192.168.20.93:2181"; ExponentialBackoffRetry retryPolicy = new ExponentialBackoffRetry(1000, 3, 5000); CuratorFramework zkClient = CuratorFrameworkFactory.builder() .connectString(zkServerAddress) .sessionTimeoutMs(5000) .connectionTimeoutMs(5000) .retryPolicy(retryPolicy) .build(); zkClient.start(); return zkClient; } }
