如果要使用类似Wather的监听功能Curator必须依赖一个jar包，Maven依赖，
<dependency>
<groupId>org.apache.curator</groupId>
<artifactId>curator-recipes</artifactId>
<version>4.0.0</version>
</dependency>
有了这个依赖包，我们使用NodeCache的方式去客户端实例中注册一个监听缓存，然后实现对应的监听方法即可，这里主要有两种监听方式
NodeCacheListener：监听节点的新增，修改操作。
1 package bjsxt.curator.watcher; 2 3 import org.apache.curator.RetryPolicy; 4 import org.apache.curator.framework.CuratorFramework; 5 import org.apache.curator.framework.CuratorFrameworkFactory; 6 import org.apache.curator.framework.recipes.cache.NodeCache; 7 import org.apache.curator.framework.recipes.cache.NodeCacheListener; 8 import org.apache.curator.retry.ExponentialBackoffRetry; 9 10 public class CuratorWatcher1 { 11 12 /** zookeeper地址 */ 13 static final String CONNECT_ADDR = "192.168.2.2:2181"; 14 /** session超时时间 */ 15 static final int SESSION_OUTTIME = 5000;// ms 16 17 public static void main(String[] args) throws Exception { 18 19 // 1 重试策略：初试时间为1s 重试10次 20 RetryPolicy retryPolicy = new ExponentialBackoffRetry(1000, 10); 21 // 2 通过工厂创建连接 22 CuratorFramework cf = CuratorFrameworkFactory.builder() 23 .connectString(CONNECT_ADDR).sessionTimeoutMs(SESSION_OUTTIME) 24 .retryPolicy(retryPolicy).build(); 25 26 // 3 建立连接 27 cf.start(); 28 29 // 4 建立一个cache缓存 第三个参数代表是否压缩 30 final NodeCache cache = new NodeCache(cf, "/super", false); 31 cache.start(true); 32 cache.getListenable().addListener(new NodeCacheListener() { 33 /** 34 * <B>方法名称：</B>nodeChanged<BR> 35 * <B>概要说明：</B>触发事件为创建节点和更新节点，在删除节点的时候并不触发此操作。<BR> 36 * 37 * @see org.apache.curator.framework.recipes.cache.NodeCacheListener#nodeChanged() 38 */ 39 @Override 40 public void nodeChanged() throws Exception { 41 System.out.println("路径为：" + cache.getCurrentData().getPath()); 42 System.out.println("数据为：" 43 + new String(cache.getCurrentData().getData())); 44 System.out.println("状态为：" + cache.getCurrentData().getStat()); 45 System.out.println("---------------------------------------"); 46 } 47 }); 48 49 Thread.sleep(1000); 50 cf.create().forPath("/super", "123".getBytes()); 51 52 Thread.sleep(1000); 53 cf.setData().forPath("/super", "456".getBytes()); 54 55 Thread.sleep(1000); 56 cf.delete().forPath("/super"); 57 58 Thread.sleep(Integer.MAX_VALUE); 59 60 } 61 }
PathChildrenCacheListener：监听子节点的新增，修改，删除操作。
1 package bjsxt.curator.watcher; 2 3 import org.apache.curator.RetryPolicy; 4 import org.apache.curator.framework.CuratorFramework; 5 import org.apache.curator.framework.CuratorFrameworkFactory; 6 import org.apache.curator.framework.recipes.cache.PathChildrenCache; 7 import org.apache.curator.framework.recipes.cache.PathChildrenCache.StartMode; 8 import org.apache.curator.framework.recipes.cache.PathChildrenCacheEvent; 9 import org.apache.curator.framework.recipes.cache.PathChildrenCacheListener; 10 import org.apache.curator.retry.ExponentialBackoffRetry; 11 12 public class CuratorWatcher2 { 13 14 /** zookeeper地址 */ 15 static final String CONNECT_ADDR = "192.168.2.2:2181"; 16 /** session超时时间 */ 17 static final int SESSION_OUTTIME = 5000;// ms 18 19 public static void main(String[] args) throws Exception { 20 21 // 1 重试策略：初试时间为1s 重试10次 22 RetryPolicy retryPolicy = new ExponentialBackoffRetry(1000, 10); 23 // 2 通过工厂创建连接 24 CuratorFramework cf = CuratorFrameworkFactory.builder() 25 .connectString(CONNECT_ADDR).sessionTimeoutMs(SESSION_OUTTIME) 26 .retryPolicy(retryPolicy).build(); 27 28 // 3 建立连接 29 cf.start(); 30 31 // 4 建立一个PathChildrenCache缓存,第三个参数为是否接受节点数据内容 如果为false则不接受 32 PathChildrenCache cache = new PathChildrenCache(cf, "/super", true); 33 // 5 在初始化的时候就进行缓存监听 34 cache.start(StartMode.POST_INITIALIZED_EVENT); 35 cache.getListenable().addListener(new PathChildrenCacheListener() { 36 /** 37 * <B>方法名称：</B>监听子节点变更<BR> 38 * <B>概要说明：</B>新建、修改、删除<BR> 39 * 40 * @see org.apache.curator.framework.recipes.cache.PathChildrenCacheListener#childEvent(org.apache.curator.framework.CuratorFramework, 41 * org.apache.curator.framework.recipes.cache.PathChildrenCacheEvent) 42 */ 43 @Override 44 public void childEvent(CuratorFramework cf, 45 PathChildrenCacheEvent event) throws Exception { 46 switch (event.getType()) { 47 case CHILD_ADDED: 48 System.out.println("CHILD_ADDED :" 49 + event.getData().getPath()); 50 break; 51 case CHILD_UPDATED: 52 System.out.println("CHILD_UPDATED :" 53 + event.getData().getPath()); 54 break; 55 case CHILD_REMOVED: 56 System.out.println("CHILD_REMOVED :" 57 + event.getData().getPath()); 58 break; 59 default: 60 break; 61 } 62 } 63 }); 64 65 // 创建本身节点不发生变化 66 cf.create().forPath("/super", "init".getBytes()); 67 68 // 添加子节点 69 Thread.sleep(1000); 70 cf.create().forPath("/super/c1", "c1内容".getBytes()); 71 Thread.sleep(1000); 72 cf.create().forPath("/super/c2", "c2内容".getBytes()); 73 74 // 修改子节点 75 Thread.sleep(1000); 76 cf.setData().forPath("/super/c1", "c1更新内容".getBytes()); 77 78 // 删除子节点 79 Thread.sleep(1000); 80 cf.delete().forPath("/super/c2"); 81 82 // 删除本身节点 83 Thread.sleep(1000); 84 cf.delete().deletingChildrenIfNeeded().forPath("/super"); 85 86 Thread.sleep(Integer.MAX_VALUE); 87 88 } 89 }
