Zookeeper入门实战(3)-Curator操作Zookeeper
Apache Curator 是用于 Apache ZooKeeper 的一个Java客户端库；它包括一个高级 API 框架和实用程序，使使用 Apache ZooKeeper 更加容易和可靠。Curator 之于 ZooKeeper 就像 Guava 之于 Java。
本文件主要介绍使用 Curator 操作 Zookeeper，文中所使用到的软件版本：Java 1.8.0_191、Zookeeper 3.6.0、Junit 4.13。
1、引入依赖
<dependency> <groupId>org.apache.zookeeper</groupId> <artifactId>zookeeper</artifactId> <version>3.6.0</version> </dependency> <dependency> <groupId>org.apache.curator</groupId> <artifactId>curator-recipes</artifactId> <version>4.3.0</version> </dependency> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>4.13</version> </dependency>
2、基本操作
package com.abc.demo.general.zookeeper; import org.apache.curator.RetryPolicy; import org.apache.curator.framework.CuratorFramework; import org.apache.curator.framework.CuratorFrameworkFactory; import org.apache.curator.framework.api.BackgroundCallback; import org.apache.curator.framework.api.CuratorEvent; import org.apache.curator.retry.ExponentialBackoffRetry; import org.apache.zookeeper.CreateMode; import org.apache.zookeeper.ZooDefs; import org.apache.zookeeper.data.ACL; import org.apache.zookeeper.data.Id; import org.apache.zookeeper.data.Stat; import org.junit.After; import org.junit.Before; import org.junit.Test; import java.util.Collections; import java.util.List; import java.util.concurrent.CountDownLatch; import java.util.concurrent.Executors; /** * 使用Curator操作Zookeeper */ public class CuratorCase { //Zookeeper地址，集群多个地址间用逗号分隔，如:10.49.196.10:2181,10.49.196.11:2181,10.49.196.12:2181 private static String connectString = "10.49.196.10:2181"; private static int sessionTimeout = 20 * 1000; private static int connectionTimeout = 10 * 1000; private CuratorFramework cf; @Before public void before() { RetryPolicy retryPolicy = new ExponentialBackoffRetry(1000,3); cf = CuratorFrameworkFactory.builder() .connectString(connectString) .sessionTimeoutMs(sessionTimeout) .connectionTimeoutMs(connectionTimeout) .retryPolicy(retryPolicy) .build(); cf.start(); } @After public void after() throws Exception { cf.close(); } /** * 创建节点 */ @Test public void create() throws Exception { /* * 同步创建节点 * 1.除非指明创建节点的类型,默认是持久节点 * 2.临时节点没有子节点；所以递归创建出来的节点,只有最后的数据节点才是指定类型的节点,其父节点是持久节点 */ //创建一个内容为空的节点 cf.create().forPath("/curator/node1"); //创建一个内容为aaa的节点 cf.create().forPath("/curator/node2", "aaa".getBytes()); //创建一个临时节点 cf.create().withMode(CreateMode.EPHEMERAL).forPath("/curator/node3"); //递归创建，最后的节点类型为临时节点 cf.create().creatingParentsIfNeeded().withMode(CreateMode.EPHEMERAL).forPath("/curator/node4/a/b"); //创建一个节点，ACL为digest:jack:tgi9UCnyPo5FJjVylKr05nAlWeg=:cdrwa cf.create().withACL(Collections.singletonList(new ACL(ZooDefs.Perms.ALL, new Id("digest", "jack:tgi9UCnyPo5FJjVylKr05nAlWeg=")))).forPath("/curator/node5"); /* * 异步创建节点 * 可以指定线程池，不指定则使用Zookeeper的EventThread线程对事件进行串行处理 */ CountDownLatch counter = new CountDownLatch(2); cf.create().inBackground(new BackgroundCallback(){ @Override public void processResult(CuratorFramework client, CuratorEvent event) throws Exception { System.out.println(event); counter.countDown(); } }, Executors.newFixedThreadPool(1)).forPath("/curator/node6"); cf.create().inBackground(new BackgroundCallback(){ @Override public void processResult(CuratorFramework client, CuratorEvent event) throws Exception { System.out.println(event); counter.countDown(); } }).forPath("/curator/node7"); counter.await(); } /** * 获取节点内容 * @throws Exception */ @Test public void getData() throws Exception { Stat stat = new Stat(); byte[] bytes = cf.getData() .storingStatIn(stat)//状态，可选 .forPath("/curator/node2"); System.out.println("状态信息:" + stat); System.out.println("内容:" + new String(bytes)); //异步获取数据 CountDownLatch counter = new CountDownLatch(1); cf.getData().inBackground(new BackgroundCallback(){ @Override public void processResult(CuratorFramework client, CuratorEvent event) throws Exception { System.out.println("event:" + event); System.out.println("内容:"+ new String(event.getData())); counter.countDown(); } }).forPath("/curator/node2"); counter.await(); } /** * 设置节点的值 * @throws Exception */ @Test public void setData() throws Exception { cf.setData() .withVersion(0) //指定版本,可选 .forPath("/curator/node2", "测试修改".getBytes()); } /** * 删除节点 * @throws Exception */ @Test public void delete() throws Exception { cf.delete() .guaranteed() //如果删除失败,只要会话有效就会不断的重试,直到删除成功为止 .deletingChildrenIfNeeded()//删除子节点，可选 .withVersion(0) //指定版本，可选 .forPath("/curator/node4"); } /** * 获取子节点 * @throws Exception */ @Test public void getChildren() throws Exception { List<String> list = cf.getChildren().forPath("/curator"); System.out.println("子节点：" + list); } }
3、监控数据变化
package com.abc.demo.general.zookeeper; import org.apache.curator.RetryPolicy; import org.apache.curator.framework.CuratorFramework; import org.apache.curator.framework.CuratorFrameworkFactory; import org.apache.curator.framework.recipes.cache.*; import org.apache.curator.retry.ExponentialBackoffRetry; import org.junit.After; import org.junit.Before; import org.junit.Test; import java.util.concurrent.*; public class CuratorWatchCase { //Zookeeper地址，集群多个地址间用逗号分隔，如:10.49.196.10:2181,10.49.196.11:2181,10.49.196.12:2181 private static String connectString = "10.49.196.10:2181"; private static int sessionTimeout = 20 * 1000; private static int connectionTimeout = 10 * 1000; private CuratorFramework cf; @Before public void before() { RetryPolicy retryPolicy = new ExponentialBackoffRetry(1000,3); cf = CuratorFrameworkFactory.builder() .connectString(connectString) .sessionTimeoutMs(sessionTimeout) .connectionTimeoutMs(connectionTimeout) .retryPolicy(retryPolicy) .build(); cf.start(); } @After public void after() throws Exception { cf.close(); } /** * 监控节点变化 * @throws Exception */ @Test public void watchNode() throws Exception { CountDownLatch counter = new CountDownLatch(1); NodeCache cache = new NodeCache(cf, "/curator/node2", false); cache.start(); cache.getListenable().addListener(new NodeCacheListener() { @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()); //某种情况下退出监控 //if (...) { // counter.countDown(); //} } }); counter.await(); } /** * 监控子节点变化 * @throws Exception */ @Test public void watchChildren() throws Exception { //使用自定义的线程池 ExecutorService threadPool = new ThreadPoolExecutor(1, 1, 0L, TimeUnit.MILLISECONDS, new LinkedBlockingQueue<Runnable>(32), Executors.defaultThreadFactory(), new ThreadPoolExecutor.AbortPolicy()); CountDownLatch counter = new CountDownLatch(1); PathChildrenCache cache = new PathChildrenCache(cf, "/curator/node2", true); cache.start(); cache.getListenable().addListener(new PathChildrenCacheListener() { @Override public void childEvent(CuratorFramework client, PathChildrenCacheEvent event) throws Exception { switch (event.getType()) { case CHILD_ADDED: System.out.println("CHILD_ADDED"); break; case CHILD_UPDATED: System.out.println("CHILD_UPDATED"); break; case CHILD_REMOVED: System.out.println("CHILD_REMOVED"); break; default: System.out.println(event.getType()); } System.out.println("子节点信息:" + event.getData()); //某种情况下退出监控 //if (...) { // counter.countDown(); //} } }, threadPool); counter.await(); threadPool.shutdownNow(); } }
可以看到不管是基本的增删改查还是监控数据变化，Curator都比原生的API好用很多。
