Curator的监听

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。

 package bjsxt.curator.watcher;

 import org.apache.curator.RetryPolicy;
 import org.apache.curator.framework.CuratorFramework;
 import org.apache.curator.framework.CuratorFrameworkFactory;
 import org.apache.curator.framework.recipes.cache.NodeCache;
 import org.apache.curator.framework.recipes.cache.NodeCacheListener;
 import org.apache.curator.retry.ExponentialBackoffRetry;

 public class CuratorWatcher1 {

     /** zookeeper地址 */
     static final String CONNECT_ADDR = "192.168.2.2:2181";
     /** session超时时间 */
     static final int SESSION_OUTTIME = 5000;// ms

     public static void main(String[] args) throws Exception {

         // 1 重试策略：初试时间为1s 重试10次
         RetryPolicy retryPolicy = new ExponentialBackoffRetry(1000, 10);
         // 2 通过工厂创建连接
         CuratorFramework cf = CuratorFrameworkFactory.builder()
                 .connectString(CONNECT_ADDR).sessionTimeoutMs(SESSION_OUTTIME)
                 .retryPolicy(retryPolicy).build();

         // 3 建立连接
         cf.start();

         // 4 建立一个cache缓存 第三个参数代表是否压缩
         final NodeCache cache = new NodeCache(cf, "/super", false);
         cache.start(true);
         cache.getListenable().addListener(new NodeCacheListener() {
             /**
              * <B>方法名称：</B>nodeChanged<BR>
              * <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>
              *
              * @see org.apache.curator.framework.recipes.cache.NodeCacheListener#nodeChanged()
              */
             @Override
             public void nodeChanged() throws Exception {
                 System.out.println("路径为：" + cache.getCurrentData().getPath());
                 System.out.println("数据为："
                         + new String(cache.getCurrentData().getData()));
                 System.out.println("状态为：" + cache.getCurrentData().getStat());
                 System.out.println("---------------------------------------");
             }
         });

         Thread.sleep(1000);
         cf.create().forPath("/super", "123".getBytes());

         Thread.sleep(1000);
         cf.setData().forPath("/super", "456".getBytes());

         Thread.sleep(1000);
         cf.delete().forPath("/super");

         Thread.sleep(Integer.MAX_VALUE);

     }
 }

PathChildrenCacheListener：监听子节点的新增，修改，删除操作。

 package bjsxt.curator.watcher;

 import org.apache.curator.RetryPolicy;
 import org.apache.curator.framework.CuratorFramework;
 import org.apache.curator.framework.CuratorFrameworkFactory;
 import org.apache.curator.framework.recipes.cache.PathChildrenCache;
 import org.apache.curator.framework.recipes.cache.PathChildrenCache.StartMode;
 import org.apache.curator.framework.recipes.cache.PathChildrenCacheEvent;
 import org.apache.curator.framework.recipes.cache.PathChildrenCacheListener;
 import org.apache.curator.retry.ExponentialBackoffRetry;

 public class CuratorWatcher2 {

     /** zookeeper地址 */
     static final String CONNECT_ADDR = "192.168.2.2:2181";
     /** session超时时间 */
     static final int SESSION_OUTTIME = 5000;// ms

     public static void main(String[] args) throws Exception {

         // 1 重试策略：初试时间为1s 重试10次
         RetryPolicy retryPolicy = new ExponentialBackoffRetry(1000, 10);
         // 2 通过工厂创建连接
         CuratorFramework cf = CuratorFrameworkFactory.builder()
                 .connectString(CONNECT_ADDR).sessionTimeoutMs(SESSION_OUTTIME)
                 .retryPolicy(retryPolicy).build();

         // 3 建立连接
         cf.start();

         // 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
         PathChildrenCache cache = new PathChildrenCache(cf, "/super", true);
         // 5 在初始化的时候就进行缓存监听
         cache.start(StartMode.POST_INITIALIZED_EVENT);
         cache.getListenable().addListener(new PathChildrenCacheListener() {
             /**
              * <B>方法名称：</B>监听子节点变更<BR>
              * <B>概要说明：</B>新建、修改、删除<BR>
              *
              * @see org.apache.curator.framework.recipes.cache.PathChildrenCacheListener#childEvent(org.apache.curator.framework.CuratorFramework,
              *      org.apache.curator.framework.recipes.cache.PathChildrenCacheEvent)
              */
             @Override
             public void childEvent(CuratorFramework cf,
                     PathChildrenCacheEvent event) throws Exception {
                 switch (event.getType()) {
                 case CHILD_ADDED:
                     System.out.println("CHILD_ADDED :"
                             + event.getData().getPath());
                     break;
                 case CHILD_UPDATED:
                     System.out.println("CHILD_UPDATED :"
                             + event.getData().getPath());
                     break;
                 case CHILD_REMOVED:
                     System.out.println("CHILD_REMOVED :"
                             + event.getData().getPath());
                     break;
                 default:
                     break;
                 }
             }
         });

         // 创建本身节点不发生变化
         cf.create().forPath("/super", "init".getBytes());

         // 添加子节点
         Thread.sleep(1000);
         cf.create().forPath("/super/c1", "c1内容".getBytes());
         Thread.sleep(1000);
         cf.create().forPath("/super/c2", "c2内容".getBytes());

         // 修改子节点
         Thread.sleep(1000);
         cf.setData().forPath("/super/c1", "c1更新内容".getBytes());

         // 删除子节点
         Thread.sleep(1000);
         cf.delete().forPath("/super/c2");

         // 删除本身节点
         Thread.sleep(1000);
         cf.delete().deletingChildrenIfNeeded().forPath("/super");

         Thread.sleep(Integer.MAX_VALUE);

     }
 }