+ Curator入门

https://www.jianshu.com/p/db65b64f38aa简介Curator是Netflix公司开源的一套zookeeper客户端框架，解决了很多Zookeeper客户端非常底层的细节开发工作，包括连接重连、反复注册Watcher和NodeExistsException异常等等。Patrixck Hunt（Zookeeper）以一句“Guava is to Java that Curator to Zookeeper”给Curator予高度评价。
Curator的maven依赖

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<!-- 对zookeeper的底层api的一些封装 -->         <dependency>             <groupId>org.apache.curator</groupId>             <artifactId>curator-framework</artifactId>             <version>2.12.0</version>         </dependency>         <!-- 封装了一些高级特性，如：Cache事件监听、选举、分布式锁、分布式Barrier -->         <dependency>             <groupId>org.apache.curator</groupId>             <artifactId>curator-recipes</artifactId>             <version>2.12.0</version>         </dependency>

基本API创建会话使用静态工程方法创建

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RetryPolicy retryPolicy = new ExponentialBackoffRetry(1000, 3); CuratorFramework client = CuratorFrameworkFactory.newClient("192.168.128.129:2181",         5000, 5000, retryPolicy);

其中RetryPolicy为重试策略，第一个参数为baseSleepTimeMs初始的sleep时间，用于计算之后的每次重试的sleep时间。第二个参数为maxRetries，最大重试次数。
使用Fluent风格api创建

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RetryPolicy retryPolicy = new ExponentialBackoffRetry(1000, 3); CuratorFramework client = CuratorFrameworkFactory.builder()         .connectString("192.168.128.129:2181")         .sessionTimeoutMs(5000)  // 会话超时时间         .connectionTimeoutMs(5000) // 连接超时时间         .retryPolicy(retryPolicy)         .namespace("base") // 包含隔离名称         .build(); client.start();

创建数据节点

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client.create().creatingParentContainersIfNeeded() // 递归创建所需父节点                 .withMode(CreateMode.PERSISTENT) // 创建类型为持久节点                 .forPath("/nodeA", "init".getBytes()); // 目录及内容

删除数据节点

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client.delete()       .guaranteed()  // 强制保证删除       .deletingChildrenIfNeeded() // 递归删除子节点       .withVersion(10086) // 指定删除的版本号       .forPath("/nodeA");

读取数据节点读数据，返回值为byte[]

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1 2	byte[] bytes = client.getData().forPath("/nodeA");         System.out.println(new String(bytes));

读stat

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Stat stat = new Stat();         client.getData()                 .storingStatIn(stat)                 .forPath("/nodeA");

修改数据节点

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client.setData()                 .withVersion(10086) // 指定版本修改                 .forPath("/nodeA", "data".getBytes());

事务

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client.inTransaction().check().forPath("/nodeA")                 .and()                 .create().withMode(CreateMode.EPHEMERAL).forPath("/nodeB", "init".getBytes())                 .and()                 .create().withMode(CreateMode.EPHEMERAL).forPath("/nodeC", "init".getBytes())                 .and()                 .commit();

其他

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client.checkExists() // 检查是否存在           .forPath("/nodeA");   client.getChildren().forPath("/nodeA"); // 获取子节点的路径

异步回调异步创建节点

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Executor executor = Executors.newFixedThreadPool(2);         client.create()                 .creatingParentsIfNeeded()                 .withMode(CreateMode.EPHEMERAL)                 .inBackground((curatorFramework, curatorEvent) -> {                     System.out.println(String.format("eventType:%s,resultCode:%s",curatorEvent.getType(),curatorEvent.getResultCode()));                 },executor)                 .forPath("path");

注：本文参考了博客
https://zjcscut.github.io/2018/12/16/zookeeper-curator-usage/#Zookeeper%E5%AE%A2%E6%88%B7%E7%AB%AFCurator%E4%BD%BF%E7%94%A8%E8%AF%A6%E8%A7%A3