本文主要是介绍Apache Curator简单介绍，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
原文链接：https://www.dubby.cn/detail.html?id=9099
提供了一个抽象级别更高的API，来操作Zookeeper，类似Guava提供的很多工具，让Java书写起来更加方便。至于有没有用，那就要看每个人自己的理解了。
1、依赖
<dependency><groupId>org.apache.curator</groupId><artifactId>curator-framework</artifactId><version>2.8.0</version>
</dependency>
更多版本和依赖
2、连接Zookeeper
RetryPolicy retryPolicy = new ExponentialBackoffRetry(1000, 3);
CuratorFramework client = CuratorFrameworkFactory.newClient("127.0.0.1:2181", retryPolicy);
client.start();
3、增删改查
/*** Zookeeper的CRUD操作*/
public class CrudExamples {/*** 给指定的ZNode设置值，不能嵌套创建目录* 如果节点已经存在，会抛异常org.apache.zookeeper.KeeperException$NodeExistsException: KeeperErrorCode = NodeExists for /path*/public static void create(CuratorFramework client, String path, byte[] payload) throws Exception {client.create().forPath(path, payload);}/*** 创建临时节点* 需要注意：虽说临时节点是session失效后立刻删除，但是并不是client一断开连接，session就立刻会失效* 失效是由zk服务端控制的，每次连接时，客户端和服务端会协商一个合理的超时时间* 如果超过了超时时间client都一直美哦与发送心跳，才回真的删除这个session创建的临时节点*/public static void createEphemeral(CuratorFramework client, String path, byte[] payload) throws Exception {client.create().withMode(CreateMode.EPHEMERAL).forPath(path, payload);}public static String createEphemeralSequential(CuratorFramework client, String path, byte[] payload) throws Exception {return client.create().withProtection().withMode(CreateMode.EPHEMERAL_SEQUENTIAL).forPath(path, payload);}public static void setData(CuratorFramework client, String path, byte[] payload) throws Exception {client.setData().forPath(path, payload);}public static void setDataAsync(CuratorFramework client, String path, byte[] payload) throws Exception {CuratorListener listener = new CuratorListener() {@Overridepublic void eventReceived(CuratorFramework client, CuratorEvent event) throws Exception {if (event != null)System.out.println(event.toString());}};client.getCuratorListenable().addListener(listener);client.setData().inBackground().forPath(path, payload);}public static void setDataAsyncWithCallback(CuratorFramework client, BackgroundCallback callback, String path, byte[] payload) throws Exception {client.setData().inBackground(callback).forPath(path, payload);}public static void delete(CuratorFramework client, String path) throws Exception {client.delete().forPath(path);}public static void guaranteedDelete(CuratorFramework client, String path) throws Exception {client.delete().guaranteed().forPath(path);}public static List<String> watchedGetChildren(CuratorFramework client, String path) throws Exception {return client.getChildren().watched().forPath(path);}public static List<String> watchedGetChildren(CuratorFramework client, String path, Watcher watcher) throws Exception {return client.getChildren().usingWatcher(watcher).forPath(path);}
}
使用上面的增删改查来测试：
public class CuratorStartupDemo {private static CuratorFramework CLIENT;private static final String CHARSET = "UTF-8";static {RetryPolicy retryPolicy = new ExponentialBackoffRetry(1000, 3);CLIENT = CuratorFrameworkFactory.newClient("127.0.0.1:2181", retryPolicy);}public static void main(String[] args) throws Exception {CLIENT.start();System.out.println(CLIENT.getZookeeperClient().getConnectionTimeoutMs());CrudExamples.create(CLIENT, "/x", "test".getBytes(CHARSET));CrudExamples.createEphemeral(CLIENT, "/e", "test".getBytes(CHARSET));CrudExamples.setData(CLIENT, "/x", UUID.randomUUID().toString().getBytes(CHARSET));CrudExamples.setDataAsync(CLIENT, "/x", UUID.randomUUID().toString().getBytes(CHARSET));CrudExamples.setDataAsyncWithCallback(CLIENT, ((client, event) -> {System.out.println(event.getPath());}), "/x", UUID.randomUUID().toString().getBytes(CHARSET));CrudExamples.createEphemeralSequential(CLIENT, "/x", "test".getBytes(CHARSET));CrudExamples.createEphemeralSequential(CLIENT, "/x", "test".getBytes(CHARSET));CrudExamples.createEphemeralSequential(CLIENT, "/x", "test".getBytes(CHARSET));CrudExamples.createEphemeralSequential(CLIENT, "/x", "test".getBytes(CHARSET));CuratorListener listener = new CuratorListener() {@Overridepublic void eventReceived(CuratorFramework client, CuratorEvent event) throws Exception {if (event != null)System.out.println(event.toString());//watcher是一次性的，每次watch后需要重新设置watcherif ("/x".equals(event.getPath())) {CrudExamples.watchedGetChildren(CLIENT, "/x");}}};CLIENT.getCuratorListenable().addListener(listener);CrudExamples.watchedGetChildren(CLIENT, "/x");CrudExamples.create(CLIENT, "/x/a", null);CrudExamples.create(CLIENT, "/x/b", null);CrudExamples.delete(CLIENT, "/x/a");CrudExamples.delete(CLIENT, "/x/b");MyWatcher myWatcher = new MyWatcher("/x", CLIENT);CrudExamples.watchedGetChildren(myWatcher.curatorFramework, myWatcher.getPath(), myWatcher);System.out.println("task completed");new CountDownLatch(1).await();}static class MyWatcher implements Watcher {private String path;private CuratorFramework curatorFramework;public MyWatcher(String path, CuratorFramework curatorFramework) {this.path = path;this.curatorFramework = curatorFramework;}@Overridepublic void process(WatchedEvent event) {System.out.println(event.toString());try {//watcher是一次性的，每次watch后需要重新设置watcherCrudExamples.watchedGetChildren(this.curatorFramework, this.getPath(), this);} catch (Exception e) {e.printStackTrace();}}public String getPath() {return path;}public CuratorFramework getCuratorFramework() {return curatorFramework;}}}
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