0 课程地址
https://coding.imooc.com/lesson/201.html#mid=12736
1 重点关注
1.1 本节内容
curator自带节点监听多次(增删改，不针对子节点)
1.2 关键代码
// 为节点添加watcher // NodeCache: 监听数据节点的变更，会触发事件 final NodeCache nodeCache = new NodeCache(cto.client, nodePath); // // buildInitial : 初始化的时候获取node的值并且缓存 nodeCache.start(true); if (nodeCache.getCurrentData() != null) { System.out.println("节点初始化数据为：" + new String(nodeCache.getCurrentData().getData())); } else { System.out.println("节点初始化数据为空..."); } nodeCache.getListenable().addListener(new NodeCacheListener() { public void nodeChanged() throws Exception { if (nodeCache.getCurrentData() == null) { System.out.println("空"); return; } String data = new String(nodeCache.getCurrentData().getData()); System.out.println("节点路径：" + nodeCache.getCurrentData().getPath() + "数据：" + data); } });
2 课程内容
3 Coding
3.1 Curator使用监听
- 启动服务端
进入到
cd /usr/local/zookeeper/bin
重启zookeeper服务端
./zkServer.sh restart
- 主类
package com.imooc.curator; import java.util.List; import org.apache.curator.RetryPolicy; import org.apache.curator.framework.CuratorFramework; import org.apache.curator.framework.CuratorFrameworkFactory; import org.apache.curator.framework.recipes.cache.ChildData; import org.apache.curator.framework.recipes.cache.NodeCache; import org.apache.curator.framework.recipes.cache.NodeCacheListener; 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.RetryNTimes; import org.apache.zookeeper.CreateMode; import org.apache.zookeeper.ZooDefs.Ids; import org.apache.zookeeper.data.Stat; public class CuratorOperator { public CuratorFramework client = null; public static final String zkServerPath = "172.26.139.4:2181"; /** * 实例化zk客户端 */ public CuratorOperator() { /** * 同步创建zk示例，原生api是异步的 * * curator链接zookeeper的策略:ExponentialBackoffRetry * baseSleepTimeMs：初始sleep的时间 * maxRetries：最大重试次数 * maxSleepMs：最大重试时间 */ // RetryPolicy retryPolicy = new ExponentialBackoffRetry(1000, 5); /** * curator链接zookeeper的策略:RetryNTimes * n：重试的次数 * sleepMsBetweenRetries：每次重试间隔的时间 */ RetryPolicy retryPolicy = new RetryNTimes(3, 5000); /** * curator链接zookeeper的策略:RetryOneTime * sleepMsBetweenRetry:每次重试间隔的时间 */ // RetryPolicy retryPolicy2 = new RetryOneTime(3000); /** * 永远重试，不推荐使用 */ // RetryPolicy retryPolicy3 = new RetryForever(retryIntervalMs) /** * curator链接zookeeper的策略:RetryUntilElapsed * maxElapsedTimeMs:最大重试时间 * sleepMsBetweenRetries:每次重试间隔 * 重试时间超过maxElapsedTimeMs后，就不再重试 */ // RetryPolicy retryPolicy4 = new RetryUntilElapsed(2000, 3000); client = CuratorFrameworkFactory.builder() .connectString(zkServerPath) .sessionTimeoutMs(10000).retryPolicy(retryPolicy) .namespace("workspace").build(); client.start(); } /** * * @Description: 关闭zk客户端连接 */ public void closeZKClient() { if (client != null) { this.client.close(); } } public static void main(String[] args) throws Exception { // 实例化 CuratorOperator cto = new CuratorOperator(); boolean isZkCuratorStarted = cto.client.isStarted(); System.out.println("当前客户的状态：" + (isZkCuratorStarted ? "连接中" : "已关闭")); // 创建节点 String nodePath = "/super/imooc"; // byte[] data = "superme".getBytes(); // cto.client.create().creatingParentsIfNeeded() // .withMode(CreateMode.PERSISTENT) // .withACL(Ids.OPEN_ACL_UNSAFE) // .forPath(nodePath, data); // 更新节点数据 // byte[] newData = "batman".getBytes(); // cto.client.setData().withVersion(0).forPath(nodePath, newData); // 删除节点 // cto.client.delete() // .guaranteed() // 如果删除失败，那么在后端还是继续会删除，直到成功 // .deletingChildrenIfNeeded() // 如果有子节点，就删除 // .withVersion(0) // .forPath(nodePath); // 读取节点数据 // Stat stat = new Stat(); // byte[] data = cto.client.getData().storingStatIn(stat).forPath(nodePath); // System.out.println("节点" + nodePath + "的数据为: " + new String(data)); // System.out.println("该节点的版本号为: " + stat.getVersion()); // 查询子节点 // List<String> childNodes = cto.client.getChildren() // .forPath(nodePath); // System.out.println("开始打印子节点："); // for (String s : childNodes) { // System.out.println(s); // } // 判断节点是否存在,如果不存在则为空 // Stat statExist = cto.client.checkExists().forPath(nodePath + "/abc"); // System.out.println(statExist); // watcher 事件 当使用usingWatcher的时候，监听只会触发一次，监听完毕后就销毁 // cto.client.getData().usingWatcher(new MyCuratorWatcher()).forPath(nodePath); // cto.client.getData().usingWatcher(new MyWatcher()).forPath(nodePath); // 为节点添加watcher // NodeCache: 监听数据节点的变更，会触发事件 final NodeCache nodeCache = new NodeCache(cto.client, nodePath); // // buildInitial : 初始化的时候获取node的值并且缓存 nodeCache.start(true); if (nodeCache.getCurrentData() != null) { System.out.println("节点初始化数据为：" + new String(nodeCache.getCurrentData().getData())); } else { System.out.println("节点初始化数据为空..."); } nodeCache.getListenable().addListener(new NodeCacheListener() { public void nodeChanged() throws Exception { if (nodeCache.getCurrentData() == null) { System.out.println("空"); return; } String data = new String(nodeCache.getCurrentData().getData()); System.out.println("节点路径：" + nodeCache.getCurrentData().getPath() + "数据：" + data); } }); // 为子节点添加watcher // PathChildrenCache: 监听数据节点的增删改，会触发事件 // String childNodePathCache = nodePath; // // cacheData: 设置缓存节点的数据状态 // final PathChildrenCache childrenCache = new PathChildrenCache(cto.client, childNodePathCache, true); // /** // * StartMode: 初始化方式 // * POST_INITIALIZED_EVENT：异步初始化，初始化之后会触发事件 // * NORMAL：异步初始化 // * BUILD_INITIAL_CACHE：同步初始化 // */ // childrenCache.start(StartMode.POST_INITIALIZED_EVENT); // // List<ChildData> childDataList = childrenCache.getCurrentData(); // System.out.println("当前数据节点的子节点数据列表："); // for (ChildData cd : childDataList) { // String childData = new String(cd.getData()); // System.out.println(childData); // } // // childrenCache.getListenable().addListener(new PathChildrenCacheListener() { // public void childEvent(CuratorFramework client, PathChildrenCacheEvent event) throws Exception { // if(event.getType().equals(PathChildrenCacheEvent.Type.INITIALIZED)){ // System.out.println("子节点初始化ok..."); // } // // else if(event.getType().equals(PathChildrenCacheEvent.Type.CHILD_ADDED)){ // String path = event.getData().getPath(); // if (path.equals(ADD_PATH)) { // System.out.println("添加子节点:" + event.getData().getPath()); // System.out.println("子节点数据:" + new String(event.getData().getData())); // } else if (path.equals("/super/imooc/e")) { // System.out.println("添加不正确..."); // } // // }else if(event.getType().equals(PathChildrenCacheEvent.Type.CHILD_REMOVED)){ // System.out.println("删除子节点:" + event.getData().getPath()); // }else if(event.getType().equals(PathChildrenCacheEvent.Type.CHILD_UPDATED)){ // System.out.println("修改子节点路径:" + event.getData().getPath()); // System.out.println("修改子节点数据:" + new String(event.getData().getData())); // } // } // }); Thread.sleep(100000); cto.closeZKClient(); boolean isZkCuratorStarted2 = cto.client.isStarted(); System.out.println("当前客户的状态：" + (isZkCuratorStarted2 ? "连接中" : "已关闭")); } public final static String ADD_PATH = "/super/imooc/d"; }
- linux客户端修改节点（修改多次）
--启动linux客户端 zkCli.sh --第1次修改 [zk: localhost:2181(CONNECTED) 17] set /workspace/super/imooc 32 cZxid = 0xf7 ctime = Tue Apr 09 06:58:32 CST 2024 mZxid = 0xfa mtime = Tue Apr 09 07:06:47 CST 2024 pZxid = 0xf7 cversion = 0 dataVersion = 1 aclVersion = 0 ephemeralOwner = 0x0 dataLength = 2 numChildren = 0 --第2次修改 [zk: localhost:2181(CONNECTED) 18] set /workspace/super/imooc 31 cZxid = 0xf7 ctime = Tue Apr 09 06:58:32 CST 2024 mZxid = 0xfb mtime = Tue Apr 09 07:06:49 CST 2024 pZxid = 0xf7 cversion = 0 dataVersion = 2 aclVersion = 0 ephemeralOwner = 0x0 dataLength = 2 numChildren = 0 --删除 [zk: localhost:2181(CONNECTED) 19] delete /workspace/super/imooc --新增 [zk: localhost:2181(CONNECTED) 20] create /workspace/super/imooc 78 Created /workspace/super/imooc [zk: localhost:2181(CONNECTED) 21]
- 打印日志（监听多次）
2024-04-09 07:06:35,045 [main] [org.apache.zookeeper.Environment.logEnv(Environment.java:100)] - [INFO] Client environment:user.home=C:\Users\18612 2024-04-09 07:06:35,045 [main] [org.apache.zookeeper.Environment.logEnv(Environment.java:100)] - [INFO] Client environment:user.dir=D:\project\xin\zk_sts_imooc\imooc-zk-curator-maven 2024-04-09 07:06:35,046 [main] [org.apache.zookeeper.ZooKeeper.<init>(ZooKeeper.java:441)] - [INFO] Initiating client connection, connectString=172.26.139.4:2181 sessionTimeout=10000 watcher=org.apache.curator.ConnectionState@5158b42f 2024-04-09 07:06:35,154 [main-SendThread(172.26.139.4:2181)] [org.apache.zookeeper.ClientCnxn$SendThread.logStartConnect(ClientCnxn.java:1035)] - [INFO] Opening socket connection to server 172.26.139.4/172.26.139.4:2181. Will not attempt to authenticate using SASL (unknown error) 2024-04-09 07:06:35,155 [main] [org.apache.curator.framework.imps.CuratorFrameworkImpl.start(CuratorFrameworkImpl.java:326)] - [INFO] Default schema 当前客户的状态：连接中 2024-04-09 07:06:35,158 [main-SendThread(172.26.139.4:2181)] [org.apache.zookeeper.ClientCnxn$SendThread.primeConnection(ClientCnxn.java:877)] - [INFO] Socket connection established to 172.26.139.4/172.26.139.4:2181, initiating session 2024-04-09 07:06:35,165 [main-SendThread(172.26.139.4:2181)] [org.apache.zookeeper.ClientCnxn$SendThread.onConnected(ClientCnxn.java:1302)] - [INFO] Session establishment complete on server 172.26.139.4/172.26.139.4:2181, sessionid = 0x1003feb17e7000b, negotiated timeout = 10000 2024-04-09 07:06:35,171 [main-EventThread] [org.apache.curator.framework.state.ConnectionStateManager.postState(ConnectionStateManager.java:237)] - [INFO] State change: CONNECTED 节点初始化数据为：44 节点路径：/super/imooc数据：32 节点路径：/super/imooc数据：31 空 节点路径：/super/imooc数据：78
诸葛
