zookeeper使用
个人博客:https://suveng.github.io/blog/
源码:https://gitee.com/suwenguang/test
zookeeper集群角色:
- leader 主
- follower 从
- observer 观察者 :不参与写的选举,但是提供读
概念:
数据模型
zookeeper的数据模型和文件系统类似,每一个节点称为:znode. 是zookeeper中的最小数据单元。每一个znode上都可以
保存数据和挂载子节点。 从而构成一个层次化的属性结构
节点特性
持久化节点 : 节点创建后会一直存在zookeeper服务器上,直到主动删除
持久化有序节点 :每个节点都会为它的一级子节点维护一个顺序
临时节点 : 临时节点的生命周期和客户端的会话保持一致。当客户端会话失效,该节点自动清理
临时有序节点 : 在临时节点上多勒一个顺序性特性
会话
watcherzookeeper提供了分布式数据发布/订阅****,zookeeper****允许客户端向服务器注册一个watcher监听。当服务器端的节点触发指定事件的时候
**会触发watcher。服务端会向客户端发送一个事件通知****watcher的通知是一次性,一旦触发一次通知后,该watcher就失效
ACL
zookeeper提供控制节点访问权限的功能,用于有效的保证zookeeper中数据的安全性。避免误操作而导致系统出现重大事故。CREATE /READ/WRITE/DELETE/ADMIN
zookeeper的命令操作
create [-s] [-e] path data acl
-s 表示节点是否有序
-e 表示是否为临时节点
默认情况下,是持久化节点get path [watch]
获得指定 path的信息set path data [version]
修改节点 path对应的data
乐观锁的概念
数据库里面有一个 version 字段去控制数据行的版本号delete path [version]
删除节点
stat信息
cversion = 0 子节点的版本号
aclVersion = 0 表示acl的版本号,修改节点权限
dataVersion = 1 表示的是当前节点数据的版本号
czxid 节点被创建时的事务ID
mzxid 节点最后一次被更新的事务ID
pzxid 当前节点下的子节点最后一次被修改时的事务ID
ctime = Sat Aug 05 20:48:26 CST 2017
mtime = Sat Aug 05 20:48:50 CST 2017
java API操作zookeeper
demo实例我已经放在gitee上面。在zookeeper_demo的模块下面。
https://gitee.com/suwenguang/test
注意需要导入jar
<dependency><groupId>org.apache.zookeeper</groupId><artifactId>zookeeper</artifactId><version>3.4.8</version> </dependency>
package 操作zookeeper.javaAPI;import org.apache.zookeeper.*;
import org.apache.zookeeper.data.ACL;
import org.apache.zookeeper.data.Id;
import org.apache.zookeeper.data.Stat;import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.CountDownLatch;/*** author Veng Su* email 1344114844@qq.com* date 18-9-16 下午1:19*/
//这里实现watcher借口是为了方便构造zookeeper对象
public class APIdemo implements Watcher {public final static String CONNECTSTRING = "192.168.0.201:2181,192.168.0.203:2181,192.168.0.204:2181";public static CountDownLatch countDownLatch = new CountDownLatch(1);//计数器用于同步连接public static ZooKeeper zooKeeper;//zookeeper对象public static Stat stat = new Stat();//不给的全局,状态会话会丢失,导致执行失败public static void main(String[] args) throws Exception {APIdemo apIdemo = new APIdemo();zooKeeper = new ZooKeeper(CONNECTSTRING, 500, new APIdemo());//创建zookeeper对象countDownLatch.await();System.out.println(zooKeeper.getState());
//注意我都是写死的节点。便于学习
// System.out.println(zooKeeper.getData("/suveng",apIdemo,stat));
// apIdemo.delete();//这里是删除节点,注意要有才能删除
// apIdemo.get(apIdemo);//这里是获取节点
// apIdemo.create();//创建节点
// apIdemo.set();//修改节点
// Thread.sleep(2000);
//
// Thread.sleep(1000);
// zooKeeper.create("/suveng/sds", "dddd".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE,CreateMode.PERSISTENT);
// System.out.println(zooKeeper.getChildren("/suveng",true));// 权限控制部分:ip,digest,world,super
// zooKeeper.addAuthInfo("digest","root:root".getBytes());//第一种方式做权限ACL acl=new ACL(ZooDefs.Perms.CREATE, new Id("digest","root:root"));List<ACL> acls=new ArrayList<>();acls.add(acl);zooKeeper.create("/suveng/auth","2122".getBytes(),acls,CreateMode.PERSISTENT);//第二种方式做权限
// zooKeeper.addAuthInfo("digest","root:root".getBytes());//创建新的客户端APIdemo apIdemo1=new APIdemo();ZooKeeper zooKeeper1=new ZooKeeper(CONNECTSTRING,5000,apIdemo1);zooKeeper1.getData("/suveng/auth",true,new Stat());}private void create() {//createString res = null;try {res = zooKeeper.create("/suveng", "hello,suwenguang".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);} catch (KeeperException | InterruptedException e) {e.printStackTrace();}System.out.println("create " + res);}private String set() throws KeeperException, InterruptedException {zooKeeper.setData("/suveng", "dddd".getBytes(), -1);return null;}private void get(APIdemo apIdemo) throws KeeperException, InterruptedException {zooKeeper.getData("/suveng", apIdemo, stat);}private void delete() throws KeeperException, InterruptedException {zooKeeper.delete("/suveng",-1);}//watcher 的实现方法@Overridepublic void process(WatchedEvent watchedEvent) {if (watchedEvent.getState() == Event.KeeperState.SyncConnected) {if (watchedEvent.getType() == Event.EventType.None && watchedEvent.getPath() == null) {countDownLatch.countDown();System.out.println(watchedEvent.getState());} else if (watchedEvent.getType() == Event.EventType.NodeDataChanged) {try {System.out.println("path---->" + watchedEvent.getPath() + " |data change--->" +zooKeeper.getData(watchedEvent.getPath(), true, stat));} catch (KeeperException e) {e.printStackTrace();} catch (InterruptedException e) {e.printStackTrace();}} else if (watchedEvent.getType() == Event.EventType.NodeCreated) {try {System.out.println("path---->" + watchedEvent.getPath() + " |created--->" +zooKeeper.getData(watchedEvent.getPath(), true, stat));} catch (KeeperException e) {e.printStackTrace();} catch (InterruptedException e) {e.printStackTrace();}} else if (watchedEvent.getType() == Event.EventType.NodeDeleted) {try {System.out.println("path---->" + watchedEvent.getPath() + " |data deleted--->" +zooKeeper.getData(watchedEvent.getPath(), true, stat));} catch (KeeperException e) {e.printStackTrace();} catch (InterruptedException e) {e.printStackTrace();}} else if (watchedEvent.getType() == Event.EventType.NodeChildrenChanged) {try {System.out.println("path---->" + watchedEvent.getPath() + " |data child changed--->" +zooKeeper.getData(watchedEvent.getPath(), true, stat));} catch (KeeperException e) {e.printStackTrace();} catch (InterruptedException e) {e.printStackTrace();}}}}
}
权限控制模式
schema:授权对象
ip : 192.168.1.1
Digest : username:password
world : 开放式的权限控制模式,数据节点的访问权限对所有用户开放。 world:anyone
super :超级用户,可以对zookeeper上的数据节点进行操作
连接状态
KeeperStat.Expired 在一定时间内客户端没有收到服务器的通知, 则认为当前的会话已经过期了。
KeeperStat.Disconnected 断开连接的状态
KeeperStat.SyncConnected 客户端和服务器端在某一个节点上建立连接,并且完成一次version、zxid同步
KeeperStat.authFailed 授权失败
事件类型
NodeCreated 当节点被创建的时候,触发
NodeChildrenChanged 表示子节点被创建、被删除、子节点数据发生变化
NodeDataChanged 节点数据发生变化
NodeDeleted 节点被删除
None 客户端和服务器端连接状态发生变化的时候,事件类型就是None
zkClient 操作zookeeper
注意:需要导入jar
zkClient只是简单的封装了Java的zookeeper API。但是总体比Java的要好用,支持递归创建和递归删除。订阅的时候也比较方便。
实例代码依然是放在了gitee上面。
package 操作zookeeper.zkclientdemo;import org.I0Itec.zkclient.IZkDataListener;
import org.I0Itec.zkclient.ZkClient;
import org.apache.zookeeper.CreateMode;
import org.apache.zookeeper.ZooDefs;
import org.apache.zookeeper.data.ACL;
import org.apache.zookeeper.data.Id;
import org.junit.Test;import java.util.ArrayList;
import java.util.List;/*** author Veng Su* email 1344114844@qq.com* date 18-9-16 下午4:24*/
public class Zkclientdemo {public final static String CONNECTSTRING = "192.168.0.201:2181,192.168.0.203:2181,192.168.0.204:2181";public static ZkClient geetInstance() {return new ZkClient(CONNECTSTRING, 5000);}@Testpublic void testcreate() {ZkClient zkClient = Zkclientdemo.geetInstance();zkClient.createEphemeral("/zktest1");ACL acl=new ACL(ZooDefs.Perms.CREATE, new Id("digest","root:root"));List<ACL> acls=new ArrayList<>();acls.add(acl);zkClient.createEphemeral("/zktest2",acls);zkClient.createEphemeral("/zktest3","324".getBytes(),acls);zkClient.create("/zktest","21".getBytes(), CreateMode.PERSISTENT);//递归创建zkClient.createPersistent("/digui0/digui1/digui2/digui3",true);System.out.println("success");}@Testpublic void testdelete() {ZkClient zkClient = Zkclientdemo.geetInstance();//普通删除zkClient.delete("/zktest");zkClient.delete("/zktest1");zkClient.delete("/zktest2");zkClient.delete("/zktest3");//递归删除zkClient.deleteRecursive("/digui0");boolean is = zkClient.exists("/suveng");System.out.println(is);}@Testpublic void testWatchers() throws InterruptedException {ZkClient zkClient = Zkclientdemo.geetInstance();zkClient.subscribeDataChanges("/suveng", new IZkDataListener() {@Overridepublic void handleDataChange(String s, Object o) throws Exception {System.out.println(s+"->"+o);}@Overridepublic void handleDataDeleted(String s) throws Exception {}});zkClient.writeData("/suveng","suwenguang");Thread.sleep(1000);}}
curator操作zookeeper
curator是netflix公司开源的。提供了各种使用场景的封装
curator-framework 提供了fluent 风格api
curator-replice 提供实现封装
fluent风格介绍。也就是链式操作如下
package 操作zookeeper.curator;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.framework.api.transaction.CuratorTransactionResult;
import org.apache.curator.framework.recipes.cache.PathChildrenCache;
import org.apache.curator.retry.ExponentialBackoffRetry;
import org.apache.zookeeper.CreateMode;
import org.apache.zookeeper.data.Stat;
import org.junit.Test;import java.util.Collection;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;/*** author Veng Su* email 1344114844@qq.com* date 18-9-16 下午6:32*/
public class CuratorDemo {public final static String CONNECTSTRING = "192.168.0.201:2181,192.168.0.203:2181,192.168.0.204:2181";public static CuratorFramework getInstance() {return CuratorFrameworkFactory.builder().connectString(CONNECTSTRING).sessionTimeoutMs(5000).retryPolicy(new ExponentialBackoffRetry(1000, 5)).build();}// 测试创建@Testpublic void testCreate() throws Exception {CuratorFramework curatorFramework = CuratorDemo.getInstance();curatorFramework.start();curatorFramework.create().creatingParentsIfNeeded().withMode(CreateMode.PERSISTENT).forPath("/suveng/testcurator");}// 测试删除@Testpublic void testDelete() throws Exception {CuratorFramework curatorFramework = CuratorDemo.getInstance();curatorFramework.start();curatorFramework.delete().deletingChildrenIfNeeded()
// .withVersion().forPath("/suveng/testcurator");}//测试getdata@Testpublic void testGet() throws Exception {CuratorFramework curatorFramework = CuratorDemo.getInstance();curatorFramework.start();Stat stat = new Stat();byte[] bytes = curatorFramework.getData().storingStatIn(stat).forPath("/suveng");System.out.println(new String(bytes));System.out.println("stat->" + stat);}// 测试setdata@Testpublic void testSet() throws Exception {CuratorFramework curatorFramework = CuratorDemo.getInstance();curatorFramework.start();curatorFramework.setData().forPath("/suveng", "knickknack".getBytes());}//测试异步@Testpublic void testasynchronous() throws Exception {CuratorFramework curatorFramework = CuratorDemo.getInstance();curatorFramework.start();ExecutorService executorService = Executors.newFixedThreadPool(1);CountDownLatch countDownLatch = new CountDownLatch(1);//创建临时节点curatorFramework.create().withMode(CreateMode.EPHEMERAL).inBackground(new BackgroundCallback() {@Overridepublic void processResult(CuratorFramework curatorFramework, CuratorEvent curatorEvent) throws Exception {System.out.println(Thread.currentThread().getName() + "这是异步的回调函数" + " result code->" + curatorEvent.getResultCode() + "" +"curator type" + curatorEvent.getType());countDownLatch.countDown();}}, executorService).forPath("/suveng/linshi");//不给其他线程默认是当前线程。countDownLatch.await();System.out.println(Thread.currentThread().getName() + "main线程");executorService.shutdown();}//事务@Testpublic void testTransaction() throws Exception {CuratorFramework curatorFramework = CuratorDemo.getInstance();curatorFramework.start();Collection<CuratorTransactionResult> curatorTransactions = curatorFramework.inTransaction().create().withMode(CreateMode.EPHEMERAL).forPath("/suveng/transaction").and().setData().forPath("/suveng", "sdfsdfsd".getBytes()).and().commit();for (CuratorTransactionResult result : curatorTransactions) {System.out.println(result.getForPath() + "->" + result.getType());}}// 测试watcher
// patchcache 监视一个节点的子节点下的创建,删除,更新
// nodecache 监视一个节点的创建,删除,更新
// Treecache patchcache + nodecache 合体 监视路径下的创建,删除,更新,并且缓存路径 所有子节点的数据@Testpublic void testWatcher() throws Exception {CuratorFramework curatorFramework = CuratorDemo.getInstance();curatorFramework.start();// NodeCache nodeCache=new NodeCache(curatorFramework,"/suveng",false);
// nodeCache.start();
//
// nodeCache.getListenable().addListener(()-> System.out.println("节点数据发生改变,改变后的数据"+new String(nodeCache.getCurrentData().getData())));
// curatorFramework.setData().forPath("/suveng","sdfasfasfda".getBytes());
// Thread.sleep(2000);PathChildrenCache childrenCache = new PathChildrenCache(curatorFramework, "/suveng", true);childrenCache.start(PathChildrenCache.StartMode.POST_INITIALIZED_EVENT);childrenCache.getListenable().addListener((curatorFramework1, pathChildrenCacheEvent) -> {switch (pathChildrenCacheEvent.getType()) {case CONNECTION_RECONNECTED:System.out.println("reconnetc");break;case CHILD_ADDED:System.out.println("child add");break;case CHILD_REMOVED:System.out.println("child remove");break;case CHILD_UPDATED:System.out.println("child update");break;default:break;}});// curatorFramework.setData().forPath("/suveng","sdfsd".getBytes());// curatorFramework.delete().forPath("/suveng/test");curatorFramework.create().withMode(CreateMode.PERSISTENT).forPath("/suveng/test");TimeUnit.SECONDS.sleep(1);curatorFramework.setData().forPath("/suveng/test","sfs".getBytes());TimeUnit.SECONDS.sleep(1);}@Testpublic void testInit() {
// 创建会话的两种方式
// 第一种 normalCuratorFramework curatorFramework = CuratorFrameworkFactory.newClient(CONNECTSTRING, 5000, 5000, new ExponentialBackoffRetry(1000, 3));curatorFramework.start();
// 第二种 fluentCuratorFramework curatorFramework2 = CuratorFrameworkFactory.builder().connectString(CONNECTSTRING).sessionTimeoutMs(5000).retryPolicy(new ExponentialBackoffRetry(1000, 5)).build();curatorFramework2.start();System.out.println("success ");}
}
private void makeFluent(Customer customer) {customer.newOrder().with(6, "TAL").with(5, "HPK").skippable().with(3, "LGV").priorityRush();
}
curator的重试策略
ExponentialBackoffRetry() 衰减重试
RetryNTimes 指定最大重试次数
RetryOneTime 仅重试一次
RetryUnitilElapsed 一直重试知道规定的时间
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