Curator入门教程1
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简介
Curator是Netflix开源的一套ZooKeeper客户端框架. Netflix在使用ZooKeeper的过程中发现ZooKeeper自带的客户端太底层, 应用方在使用的时候需要自己处理很多事情, 于是在它的基础上包装了一下, 提供了一套更好用的客户端框架。
1、zookekeeper基本功能
连接zookeeper,对节点进行crud、回调函数、判断节点是否存在
package bjsxt.curator.base; import java.util.List; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; 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.ZooKeeper.States; import org.apache.zookeeper.data.Stat; public class CuratorBase { /** zookeeper地址 */ static final String CONNECT_ADDR = "192.168.0.4:2181,192.168.0.9:2181,192.168.0.6:2181"; /** 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) // .namespace("super") .build(); //3 开启连接 cf.start(); System.out.println(States.CONNECTED); System.out.println(cf.getState()); // 新加、删除 //4 建立节点 指定节点类型（不加withMode默认为持久类型节点）、路径、数据内容 //cf.create().creatingParentsIfNeeded().withMode(CreateMode.PERSISTENT).forPath("/super/c1","c1内容".getBytes()); //5 删除节点 // cf.delete().guaranteed().deletingChildrenIfNeeded().forPath("/super"); // 读取、修改 //创建节点 /* cf.create().creatingParentsIfNeeded().withMode(CreateMode.PERSISTENT).forPath("/super/c1","c1内容".getBytes()); cf.create().creatingParentsIfNeeded().withMode(CreateMode.PERSISTENT).forPath("/super/c2","c2内容".getBytes()); //读取节点 String ret1 = new String(cf.getData().forPath("/super/c2")); System.out.println("修改前c2节点====="+ret1); //修改节点 cf.setData().forPath("/super/c2", "修改c2内容".getBytes()); String ret2 = new String(cf.getData().forPath("/super/c2")); System.out.println("修改后c2节点====="+ret2);*/ // 绑定回调函数 ExecutorService pool = Executors.newCachedThreadPool(); cf.create().creatingParentsIfNeeded().withMode(CreateMode.PERSISTENT) .inBackground(new BackgroundCallback() { @Override public void processResult(CuratorFramework cf, CuratorEvent ce) throws Exception { System.out.println("code:" + ce.getResultCode()); System.out.println("type:" + ce.getType()); System.out.println("线程为:" + Thread.currentThread().getName()); } }, pool) .forPath("/super/c3","c3内容".getBytes()); Thread.sleep(Integer.MAX_VALUE); // 读取子节点getChildren方法 和 判断节点是否存在checkExists方法 /** List<String> list = cf.getChildren().forPath("/super"); for(String p : list){ System.out.println(p); } Stat stat = cf.checkExists().forPath("/super/c3"); System.out.println(stat); Thread.sleep(2000); cf.delete().guaranteed().deletingChildrenIfNeeded().forPath("/super"); */ //cf.delete().guaranteed().deletingChildrenIfNeeded().forPath("/super"); cf.close(); } }
2、watcher方式一（监听当前节点发生变更）
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 = "192.168.0.4:2181,192.168.0.9:2181,192.168.0.6:2181"; /** 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 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("监听节点路径=====" + cache.getCurrentData().getPath()); System.out.println("数据=====" + new String(cache.getCurrentData().getData())); System.out.println("状态=====" + 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); } }
3、watcher方式二（监听当前节点的子节点发生变更）
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.PathChildrenCacheEvent; import org.apache.curator.framework.recipes.cache.PathChildrenCacheListener; import org.apache.curator.framework.recipes.cache.PathChildrenCache.StartMode; import org.apache.curator.retry.ExponentialBackoffRetry; public class CuratorWatcher2 { /** zookeeper地址 */ static final String CONNECT_ADDR = "192.168.0.4:2181,192.168.0.9:2181,192.168.0.6:2181"; /** 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("新增子节点 =====" + event.getData().getPath()); break; case CHILD_UPDATED: System.out.println("修改子节点=====" + event.getData().getPath()); break; case CHILD_REMOVED: System.out.println("删除子节点=====" + 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); } }
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