标签:ice fixed 网络通 out watcher receive style xid dede
准备工作:
首先在新建一个maven项目ZK-Demo,然后在pom.xml里面引入zk的依赖
<dependency> <groupId>org.apache.zookeeper</groupId> <artifactId>zookeeper</artifactId> <version>3.4.10</version> </dependency>
package com.study.demo.zk; import java.io.IOException; import java.util.concurrent.CountDownLatch; import org.apache.zookeeper.WatchedEvent; import org.apache.zookeeper.Watcher; import org.apache.zookeeper.Watcher.Event.KeeperState; import org.apache.zookeeper.ZooKeeper; //连接zk并监听事件 public class ZKDemo implements Watcher { private static final CountDownLatch cdl = new CountDownLatch(1); public static void main(String[] args) throws IOException { ZooKeeper zk = new ZooKeeper("192.168.152.130:2181", 5000, new ZKDemo()); System.out.println(zk.getState()); try { cdl.await(); } catch (Exception e) { System.out.println("ZK Session established."); } } //监听到事件时进行处理 public void process(WatchedEvent event) { System.out.println("Receive watched event:" + event); if (KeeperState.SyncConnected == event.getState()) { cdl.countDown(); } } }
输出结果:
CONNECTING
Receive watched event:WatchedEvent state:SyncConnected type:None path:null
package com.study.demo.zk; import java.io.IOException; import java.util.concurrent.CountDownLatch; import org.apache.zookeeper.CreateMode; import org.apache.zookeeper.KeeperException; import org.apache.zookeeper.WatchedEvent; import org.apache.zookeeper.Watcher; import org.apache.zookeeper.Watcher.Event.KeeperState; import org.apache.zookeeper.ZooDefs.Ids; import org.apache.zookeeper.ZooKeeper; //创建znode并监听事件 public class ZKOperateDemo implements Watcher { private static final CountDownLatch cdl = new CountDownLatch(1); public static void main(String[] args) throws IOException, InterruptedException, KeeperException { ZooKeeper zk = new ZooKeeper("192.168.152.130:2181", 5000, new ZKOperateDemo()); cdl.await(); String path1 = zk.create("/zk-test-", "123".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL); System.out.println("Success create path: " + path1); String path2 = zk.create("/zk-test-", "456".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL_SEQUENTIAL); System.out.println("Success create path: " + path2); } //监听到事件时进行处理 public void process(WatchedEvent event) { System.out.println("Receive watched event:" + event); if (KeeperState.SyncConnected == event.getState()) { cdl.countDown(); } } }
输出结果:
Receive watched event:WatchedEvent state:SyncConnected type:None path:null
Success create path: /zk-test-
Success create path: /zk-test-0000000011
package com.study.demo.zk; import java.io.IOException; import java.util.concurrent.CountDownLatch; import org.apache.zookeeper.CreateMode; import org.apache.zookeeper.KeeperException; import org.apache.zookeeper.WatchedEvent; import org.apache.zookeeper.Watcher; import org.apache.zookeeper.Watcher.Event.EventType; import org.apache.zookeeper.Watcher.Event.KeeperState; import org.apache.zookeeper.ZooDefs.Ids; import org.apache.zookeeper.ZooKeeper; import org.apache.zookeeper.data.Stat; //改变znode数据并监听事件 public class ZKDataDemo implements Watcher { private static final CountDownLatch cdl = new CountDownLatch(1); private static ZooKeeper zk = null; private static Stat stat = new Stat(); public static void main(String[] args) throws IOException, InterruptedException, KeeperException { zk = new ZooKeeper("192.168.152.130:2181", 5000, new ZKDataDemo()); cdl.await(); zk.create("/zk-test", "123".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL); System.out.println(new String(zk.getData("/zk-test", true, stat))); zk.getData("/zk-test", true, stat); System.out.println(stat.getCzxid() + ", " + stat.getMzxid() + ", " + stat.getVersion()); zk.setData("/zk-test", "123".getBytes(), -1); Thread.sleep(Integer.MAX_VALUE); } //监听到事件时进行处理 public void process(WatchedEvent event) { if (KeeperState.SyncConnected == event.getState()) { if (EventType.None == event.getType() && null == event.getPath()) { cdl.countDown(); } else if (event.getType() == EventType.NodeDataChanged) { try { System.out.println(new String(zk.getData(event.getPath(), true, stat))); System.out.println(stat.getCzxid() + ", " + stat.getMzxid() + ", " + stat.getVersion()); } catch (Exception e) { } } } } }
输出结果:
123
4294967354, 4294967354, 0
123
4294967354, 4294967355, 1
package com.study.demo.zk; import java.io.IOException; import java.util.List; import java.util.concurrent.CountDownLatch; import org.apache.zookeeper.CreateMode; import org.apache.zookeeper.KeeperException; import org.apache.zookeeper.WatchedEvent; import org.apache.zookeeper.Watcher; import org.apache.zookeeper.Watcher.Event.EventType; import org.apache.zookeeper.Watcher.Event.KeeperState; import org.apache.zookeeper.ZooDefs.Ids; import org.apache.zookeeper.ZooKeeper; //改变子节点并监听事件 public class ZKChildrenDemo implements Watcher { private static final CountDownLatch cdl = new CountDownLatch(1); private static ZooKeeper zk = null; public static void main(String[] args) throws IOException, InterruptedException, KeeperException { zk = new ZooKeeper("192.168.152.130:2181", 5000, new ZKChildrenDemo()); cdl.await(); zk.create("/zk-test", "123".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT); zk.create("/zk-test/c1", "456".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL); List<String> list = zk.getChildren("/zk-test", true); for (String str : list) System.out.println(str); zk.create("/zk-test/c2", "789".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL); Thread.sleep(Integer.MAX_VALUE); } //监听到事件时进行处理 public void process(WatchedEvent event) { if (KeeperState.SyncConnected == event.getState()) if (EventType.None == event.getType() && null == event.getPath()) { cdl.countDown(); } else if (event.getType() == EventType.NodeChildrenChanged) { try { System.out.println("Child: " + zk.getChildren(event.getPath(), true)); } catch (Exception e) { } } } }
输出结果:
c1
Child: [c1, c2]
package com.study.demo.zk; import java.io.IOException; import java.util.List; import java.util.concurrent.CountDownLatch; import org.apache.zookeeper.AsyncCallback; import org.apache.zookeeper.CreateMode; import org.apache.zookeeper.KeeperException; import org.apache.zookeeper.WatchedEvent; import org.apache.zookeeper.Watcher; import org.apache.zookeeper.Watcher.Event.EventType; import org.apache.zookeeper.Watcher.Event.KeeperState; import org.apache.zookeeper.ZooDefs.Ids; import org.apache.zookeeper.ZooKeeper; import org.apache.zookeeper.data.Stat; //异步调用并完成回调 class ChildrenCallback implements AsyncCallback.Children2Callback { public void processResult(int rc, String path, Object ctx, List<String> children, Stat stat) { System.out.println( "Child: " + rc + ", path: " + path + ", ctx: " + ctx + ", children: " + children + ", stat: " + stat); } } public class ZKChildrenAsyncDemo implements Watcher { private static final CountDownLatch cdl = new CountDownLatch(1); private static ZooKeeper zk = null; public static void main(String[] args) throws IOException, InterruptedException, KeeperException { zk = new ZooKeeper("192.168.152.130:2181", 5000, new ZKChildrenAsyncDemo()); cdl.await(); zk.create("/zk-test", "123".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT); zk.create("/zk-test/c1", "456".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL); zk.getChildren("/zk-test", true, new ChildrenCallback(), "ok"); Thread.sleep(Integer.MAX_VALUE); } //监听到事件时进行处理 public void process(WatchedEvent event) { if (KeeperState.SyncConnected == event.getState()) if (EventType.None == event.getType() && null == event.getPath()) { cdl.countDown(); } else if (event.getType() == EventType.NodeChildrenChanged) { try { System.out.println("Child: " + zk.getChildren(event.getPath(), true)); } catch (Exception e) { } } } }
输出结果:
Child: 0, path: /zk-test, ctx: ok, children: [c1], stat: 4294967369,4294967369,1535536716381,1535536716381,0,1,0,0,3,1,4294967370
package com.study.demo.zk; import java.io.IOException; import java.util.concurrent.CountDownLatch; import org.apache.zookeeper.AsyncCallback; import org.apache.zookeeper.CreateMode; import org.apache.zookeeper.KeeperException; import org.apache.zookeeper.WatchedEvent; import org.apache.zookeeper.Watcher; import org.apache.zookeeper.Watcher.Event.KeeperState; import org.apache.zookeeper.ZooDefs.Ids; import org.apache.zookeeper.ZooKeeper; //连接后创建回调 class IStringCallback implements AsyncCallback.StringCallback { public void processResult(int rc, String path, Object ctx, String name) { System.out.println("create path result: [" + rc + ", " + path + "," + ctx + ", real path name: " + name); } } public class ZKAsyncDemo implements Watcher { private static final CountDownLatch cdl = new CountDownLatch(1); public static void main(String[] args) throws IOException, InterruptedException, KeeperException { ZooKeeper zk = new ZooKeeper("192.168.152.130:2181", 5000, new ZKAsyncDemo()); cdl.await(); zk.create("/zk-test-", "123".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL, new IStringCallback(), new String("I am context")); zk.create("/zk-test-", "456".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL, new IStringCallback(), new String("I am context")); zk.create("/zk-test-", "789".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL_SEQUENTIAL, new IStringCallback(), new String("I am context")); Thread.sleep(Integer.MAX_VALUE); } //监听到事件时进行处理 public void process(WatchedEvent event) { System.out.println("Receive watched event:" + event); if (KeeperState.SyncConnected == event.getState()) { cdl.countDown(); } } }
输出结果:
Receive watched event:WatchedEvent state:SyncConnected type:None path:null
create path result: [0, /zk-test-,I am context, real path name: /zk-test-
create path result: [-110, /zk-test-,I am context, real path name: null
create path result: [0, /zk-test-,I am context, real path name: /zk-test-0000000016
ZKClient的优点:
1)可以递归创建。在zookeeper命令行和zookeeper的原生API里面得先创建父节点才能创建子节点
2)可以递归删除。在zookeeper命令行和zookeeper的原生API里面得先删除子节点才能删除父节点
3)避免不存在的异常
准备工作:
首先在新建一个maven项目ZK-Demo,然后在pom.xml里面引入ZKClient的依赖
<dependency> <groupId>com.101tec</groupId> <artifactId>zkclient</artifactId> <version>0.10</version> </dependency>
package com.study.demo.client; import org.I0Itec.zkclient.ZkClient; /** * * @Description: ZkClient递归创建顺序节点 * @author leeSmall * @date 2018年9月2日 * */ public class CreateNodeDemo { public static void main(String[] args) { ZkClient client = new ZkClient("192.168.152.130:2181", 5000); String path = "/zk-client/c1"; // 递归创建顺序节点 true:先创建父节点/zk-client client.createPersistent(path, true); } }
创建成功:
package com.study.demo.client; import org.I0Itec.zkclient.IZkDataListener; import org.I0Itec.zkclient.ZkClient; /** * * @Description: ZkClient获取数据 * @author leeSmall * @date 2018年9月2日 * */ public class GetDataDemo { public static void main(String[] args) throws InterruptedException { String path = "/zk-client"; ZkClient client = new ZkClient("192.168.152.130:2181", 5000); //创建临时节点 client.createEphemeral(path, "123"); //注册父节点数据改变的事件 client.subscribeDataChanges(path, new IZkDataListener() { //父节点数据改变事件 public void handleDataChange(String dataPath, Object data) throws Exception { System.out.println(dataPath + " changed: " + data); } //父节点数据删除事件 public void handleDataDeleted(String dataPath) throws Exception { System.out.println(dataPath + " deleted"); } }); System.out.println(client.readData(path).toString()); client.writeData(path, "456"); Thread.sleep(1000); client.delete(path); //sleep的目的是为了更好的观察事件变化 Thread.sleep(Integer.MAX_VALUE); } }
输出结果:
123
/zk-client changed: 456
/zk-client deleted
package com.study.demo.client; import java.util.List; import org.I0Itec.zkclient.IZkChildListener; import org.I0Itec.zkclient.ZkClient; /** * * @Description: ZkClient获取子节点数据 * @author leeSmall * @date 2018年9月2日 * */ public class GetChildrenDemo { public static void main(String[] args) throws InterruptedException { String path = "/zk-client"; ZkClient client = new ZkClient("192.168.152.130:2181", 5000); //注册子节点数据改变的事件 client.subscribeChildChanges(path, new IZkChildListener() { //子节点数据改变事件 public void handleChildChange(String parentPath, List<String> currentChilds) throws Exception { System.out.println(parentPath + "的子发生变化: " + currentChilds); } }); //创建顺序节点 client.createPersistent(path); Thread.sleep(1000); //获取子节点数据 此时还没有创建获取不到 System.out.println(client.getChildren(path)); //在前面的父节点 /zk-client下创建子节点c1 client.createPersistent(path + "/c1"); Thread.sleep(1000); //删除子节点 client.delete(path + "/c1"); Thread.sleep(1000); //删除父节点 client.delete(path); Thread.sleep(Integer.MAX_VALUE); } }
输出结果:
/zk-client的子发生变化: []
[]
/zk-client的子发生变化: [c1]
/zk-client的子发生变化: []
/zk-client的子发生变化: null
curator是连接ZK应用最广泛的工具
原因如下:
1)zk应用场景(分布式锁,Master选举等等),curator包含了这些场景。
2)应用场景出现极端的情况下,curator考虑到处理了。
准备工作:
首先在新建一个maven项目ZK-Demo,然后在pom.xml里面引入curator的依赖
<dependency> <groupId>org.apache.curator</groupId> <artifactId>curator-framework</artifactId> <version>4.0.0</version> </dependency> <dependency> <groupId>org.apache.curator</groupId> <artifactId>curator-recipes</artifactId> <version>4.0.0</version> </dependency>
package com.study.demo.curator; import org.apache.curator.RetryPolicy; import org.apache.curator.framework.CuratorFramework; import org.apache.curator.framework.CuratorFrameworkFactory; import org.apache.curator.retry.ExponentialBackoffRetry; /** * * @Description: curator创建连接session * @author leeSmall * @date 2018年9月2日 * */ public class CreateSessionDemo { public static void main(String[] args) throws InterruptedException { RetryPolicy policy = new ExponentialBackoffRetry(1000, 3); CuratorFramework client = CuratorFrameworkFactory.builder().connectString("192.168.152.130:2181") .sessionTimeoutMs(5000).retryPolicy(policy).build(); client.start(); Thread.sleep(Integer.MAX_VALUE); } }
这里介绍一种算法:Backoff退避算法
有这样一种场景,有多个请求,如果网络出现阻塞,每1分钟重试一次。
20:25 request1(block)
20:26 request2(block)
20:27 request3(block)
当网络通顺的时候,请求都累在一起来发送
20:28 request4(通顺)request2、3、4
那么前面的请求就没有意义了,所以就有了退避算法,按照指数间隔重试,比如第一次1分钟,第二次2分钟......随着时间的推移,重试间隔越长。
package com.study.demo.curator; import org.apache.curator.framework.CuratorFramework; import org.apache.curator.framework.CuratorFrameworkFactory; import org.apache.curator.retry.ExponentialBackoffRetry; import org.apache.zookeeper.CreateMode; /** * * @Description: curator递归创建顺序节点 * @author leeSmall * @date 2018年9月2日 * */ public class CreateNodeDemo { public static void main(String[] args) throws Exception { String path = "/zk-curator/c1"; CuratorFramework client = CuratorFrameworkFactory.builder().connectString("192.168.152.130:2181") .sessionTimeoutMs(5000).retryPolicy(new ExponentialBackoffRetry(1000, 3)).build(); client.start(); client.create().creatingParentsIfNeeded().withMode(CreateMode.PERSISTENT).forPath(path, "test".getBytes()); } }
创建成功:
package com.study.demo.curator; import java.util.concurrent.CountDownLatch; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; 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; /** * * @Description: curator异步创建临时节点 * @author leeSmall * @date 2018年9月2日 * */ public class CreateNodeAsyncDemo { static CountDownLatch cdl = new CountDownLatch(2); static ExecutorService es = Executors.newFixedThreadPool(2); public static void main(String[] args) throws Exception { String path = "/zk-curator"; CuratorFramework client = CuratorFrameworkFactory.builder().connectString("192.168.152.130:2181") .sessionTimeoutMs(5000).retryPolicy(new ExponentialBackoffRetry(1000, 3)).build(); client.start(); //创建临时节点 client.create().creatingParentsIfNeeded().withMode(CreateMode.EPHEMERAL).inBackground(new BackgroundCallback() { //回调事件处理 public void processResult(CuratorFramework client, CuratorEvent event) throws Exception { System.out.println("event code: " + event.getResultCode() + ", type: " + event.getType()); cdl.countDown(); } }, es).forPath(path, "test".getBytes()); //创建临时节点 client.create().creatingParentsIfNeeded().withMode(CreateMode.EPHEMERAL).inBackground(new BackgroundCallback() { public void processResult(CuratorFramework client, CuratorEvent event) throws Exception { System.out.println("event code: " + event.getResultCode() + ", type: " + event.getType()); cdl.countDown(); } }).forPath(path, "test".getBytes()); cdl.await(); es.shutdown(); } }
输出结果:
event code: 0, type: CREATE
event code: -110, type: CREATE
package com.study.demo.curator; import org.apache.curator.framework.CuratorFramework; import org.apache.curator.framework.CuratorFrameworkFactory; import org.apache.curator.retry.ExponentialBackoffRetry; import org.apache.zookeeper.CreateMode; import org.apache.zookeeper.data.Stat; /** * * @Description: curator更新节点数据 * @author leeSmall * @date 2018年9月2日 * */ public class UpdateDataDemo { public static void main(String[] args) throws Exception { String path = "/zk-curator/c1"; CuratorFramework client = CuratorFrameworkFactory.builder().connectString("192.168.152.130:2181") .sessionTimeoutMs(5000).retryPolicy(new ExponentialBackoffRetry(1000, 3)).build(); client.start(); client.create().creatingParentsIfNeeded().withMode(CreateMode.EPHEMERAL).forPath(path, "test".getBytes()); Stat stat = new Stat(); client.getData().storingStatIn(stat).forPath(path); System.out.println("Current data: " + stat.getVersion()); System.out.println("Update data: " + client.setData().withVersion(stat.getVersion()).forPath(path, "some".getBytes()).getVersion()); } }
输出结果:
Current data: 0
Update data: 1
package com.study.demo.curator; import org.apache.curator.framework.CuratorFramework; import org.apache.curator.framework.CuratorFrameworkFactory; import org.apache.curator.retry.ExponentialBackoffRetry; import org.apache.zookeeper.CreateMode; import org.apache.zookeeper.data.Stat; /** * * @Description: curator删除节点数据 * @author leeSmall * @date 2018年9月2日 * */ public class DeleteNodeDemo { public static void main(String[] args) throws Exception { String path = "/zk-curator/c1"; CuratorFramework client = CuratorFrameworkFactory.builder().connectString("192.168.152.130:2181") .sessionTimeoutMs(5000).retryPolicy(new ExponentialBackoffRetry(1000, 3)).build(); client.start(); client.create().creatingParentsIfNeeded().withMode(CreateMode.EPHEMERAL).forPath(path, "test".getBytes()); Stat stat = new Stat(); client.getData().storingStatIn(stat).forPath(path); client.delete().deletingChildrenIfNeeded().withVersion(stat.getVersion()).forPath(path); } }
package com.study.demo.curator; 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; import org.apache.zookeeper.CreateMode; /** * * @Description: curator事件监听 * @author leeSmall * @date 2018年9月2日 * */ public class NodeCacheDemo { public static void main(String[] args) throws Exception { String path = "/zk-curator/nodecache"; CuratorFramework client = CuratorFrameworkFactory.builder().connectString("192.168.152.130:2181") .sessionTimeoutMs(5000).retryPolicy(new ExponentialBackoffRetry(1000, 3)).build(); client.start(); client.create().creatingParentsIfNeeded().withMode(CreateMode.EPHEMERAL).forPath(path, "test".getBytes()); final NodeCache nc = new NodeCache(client, path, false); nc.start(); //通过回调函数监听事件 nc.getListenable().addListener(new NodeCacheListener() { public void nodeChanged() throws Exception { System.out.println("update--current data: " + new String(nc.getCurrentData().getData())); } }); client.setData().forPath(path, "test123".getBytes()); Thread.sleep(1000); client.delete().deletingChildrenIfNeeded().forPath(path); Thread.sleep(5000); nc.close(); } }
输出结果:
update--current data: test123
Curator事件监听:
NodeCache:节点处理监听(会使用缓存)。回调接口NodeCacheListener
PathChildrenCache:子节点缓存,处理子节点变化。回调接口PathChildrenCacheListener
TreeCache:NodeCache和PathChildrenCache的结合体。回调接口TreeCacheListener
Zookeeper系列三:Zookeeper客户端的使用(Zookeeper原生API如何进行调用、ZKClient、Curator)
标签:ice fixed 网络通 out watcher receive style xid dede
原文地址:https://www.cnblogs.com/leeSmall/p/9576437.html