摘要：
ZooKeeper本身可以以单机模式安装运行，不过它的长处在于通过分布式ZooKeeper集群，基于一定的策略来保证ZooKeeper集群的稳定性和可用性，从而实现分布式应用的可靠性。zookeeper运用场景1.dubbo+zk实现rpc远程调用中，zk在其中的作用类似springcloud中的eureka注册服务中心,管理接口服务2.发布订阅3.负载均衡4.分布通知5.分布式锁zokeeper存储数据结构在zk的节点中，每个节点名称是不可以重复的,可以依次无限递增。
什么是zookeeper
1.Zookeeper是一个分布式开源框架，提供了协调分布式应用的基本服务，它向外部应用暴露一组通用服务——分布式同步、命名服务、集群维护等，简化分布式应用协调及其管理的难度，提供高性能的分布式服务。ZooKeeper本身可以以单机模式安装运行，不过它的长处在于通过分布式ZooKeeper集群，基于一定的策略来保证ZooKeeper集群的稳定性和可用性，从而实现分布式应用的可靠性。
zookeeper运用场景
1.dubbo+zk实现rpc远程调用中，zk在其中的作用类似springcloud中的eureka注册服务中心,管理接口服务
2.发布订阅
3.负载均衡
4.分布通知
5.分布式锁
zokeeper存储数据结构(类似xml数据结构)
在zk的节点中，每个节点名称是不可以重复的（实现分布式锁的关键性）,可以依次无限递增。节点的类型可以分为四种：
1.持久节点，一旦创建就保存到硬盘上面
2.临时节点，创建以后如果断开连接则该节点自动删除
3.顺序持久节点
4.顺序临时节点
每个节点都可以通过节点事件监听，对于节点的变化(增，删，改)都能获取到
例如：在使用zk作为dobbo注册服务中心的时候
在Windows环境下安装运行zk
1.下载Windows版本zk，解压以后,修改配置文件zoo_sample.cfg名字为zoo.cfg
2.在zk的bi目录下找到zkServer.bat 启动zk
3.在zk的bi目录下找到zkCli 启动zk的客户端工具,可以在cmd里面对zk的节点进行创建 修改和删除，可以根据zk的可视化管理工具进行查看,例如创建一个会员服务 ip地址是 127.0.0.1
可以通过ls 空格 / 查看当前的节点
JAVA如何操作Zookeeper
1.导入zookeeper所需要的依赖：
<dependency> <groupId>org.apache.zookeeper</groupId> <artifactId>zookeeper</artifactId> <version>3.4.14</version> </dependency>
2.编写java类创建zookeeper的节点
packagecom.zk.demo; importjava.io.IOException; importorg.apache.zookeeper.CreateMode; importorg.apache.zookeeper.KeeperException; importorg.apache.zookeeper.WatchedEvent; importorg.apache.zookeeper.Watcher; importorg.apache.zookeeper.Watcher.Event.EventType; importorg.apache.zookeeper.Watcher.Event.KeeperState; importorg.apache.zookeeper.ZooDefs.Ids; importorg.apache.zookeeper.ZooKeeper; public classCreateZookeeper { /** * ZK地址和端口 */ private static final String CONNETTION_ADDR = "127.0.0.1:2181"; /** * session超时时间 */ private static final int SESSION_TIMEOUT = 5000; public static void main(String[] args) throwsIOException, InterruptedException, KeeperException { ZooKeeper zk = new ZooKeeper(CONNETTION_ADDR, SESSION_TIMEOUT, newWatcher() { public voidprocess(WatchedEvent event) { //获取时间的状态 KeeperState keeperState =event.getState(); EventType tventType =event.getType(); //如果是建立连接 if (KeeperState.SyncConnected ==keeperState) { if (EventType.None ==tventType) { System.out.println("创建zk连接"); } } } }); zk.create("/zk", "testZookeeper".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT); System.out.println("创建节点成功"); zk.close(); } }
3.运行测试类，启动zk服务,通过命令或者可视化客户端查看生成的zk节点
SLF4J: Class path contains multiple SLF4J bindings. SLF4J: Found binding in [jar:file:/E:/developer/mvnResponsity/ch/qos/logback/logback-classic/1.1.11/logback-classic-1.1.11.jar!/org/slf4j/impl/StaticLoggerBinder.class] SLF4J: Found binding in [jar:file:/E:/developer/mvnResponsity/org/slf4j/slf4j-log4j12/1.7.26/slf4j-log4j12-1.7.26.jar!/org/slf4j/impl/StaticLoggerBinder.class] SLF4J: See http://www.slf4j.org/codes.html#multiple_bindings for an explanation. SLF4J: Actual binding is of type [ch.qos.logback.classic.util.ContextSelectorStaticBinder] 15:37:24.266 [main] INFO org.apache.zookeeper.ZooKeeper - Client environment:zookeeper.version=3.4.14-4c25d480e66aadd371de8bd2fd8da255ac140bcf, built on 03/06/2019 16:18GMT 15:37:24.268 [main] INFO org.apache.zookeeper.ZooKeeper - Client environment:host.name=NNH1J2ASSQP10BA 15:37:24.268 [main] INFO org.apache.zookeeper.ZooKeeper - Client environment:java.version=1.8.0_172 15:37:24.268 [main] INFO org.apache.zookeeper.ZooKeeper - Client environment:java.vendor=Oracle Corporation 15:37:24.268 [main] INFO org.apache.zookeeper.ZooKeeper - Client environment:java.home=E:Javajdk1.8.0_172jre 15:37:24.268 [main] INFO org.apache.zookeeper.ZooKeeper - Client environment:java.class.path=E:Javajdk1.8.0_172jrelib esources.jar;E:Javajdk1.8.0_172jrelib t.jar;E:Javajdk1.8.0_172jrelibjsse.jar;E:Javajdk1.8.0_172jrelibjce.jar;E:Javajdk1.8.0_172jrelibcharsets.jar;E:Javajdk1.8.0_172jrelibjfr.jar;E:Javajdk1.8.0_172jrelibextaccess-bridge-64.jar;E:Javajdk1.8.0_172jrelibextcldrdata.jar;E:Javajdk1.8.0_172jrelibextdnsns.jar;E:Javajdk1.8.0_172jrelibextjaccess.jar;E:Javajdk1.8.0_172jrelibextjfxrt.jar;E:Javajdk1.8.0_172jrelibextlocaledata.jar;E:Javajdk1.8.0_172jrelibext ashorn.jar;E:Javajdk1.8.0_172jrelibextsunec.jar;E:Javajdk1.8.0_172jrelibextsunjce_provider.jar;E:Javajdk1.8.0_172jrelibextsunmscapi.jar;E:Javajdk1.8.0_172jrelibextsunpkcs11.jar;E:Javajdk1.8.0_172jrelibextzipfs.jar;E:codeservletjava-zk argetclasses;E:codeservletjava-zklibzookeeper-3.4.14.jar;E:developermvnResponsityorgspringframeworkootspring-boot-starter1.5.21.RELEASEspring-boot-starter-1.5.21.RELEASE.jar;E:developermvnResponsityorgspringframeworkootspring-boot1.5.21.RELEASEspring-boot-1.5.21.RELEASE.jar;E:developermvnResponsityorgspringframeworkspring-context4.3.24.RELEASEspring-context-4.3.24.RELEASE.jar;E:developermvnResponsityorgspringframeworkspring-aop4.3.24.RELEASEspring-aop-4.3.24.RELEASE.jar;E:developermvnResponsityorgspringframeworkspring-beans4.3.24.RELEASEspring-beans-4.3.24.RELEASE.jar;E:developermvnResponsityorgspringframeworkspring-expression4.3.24.RELEASEspring-expression-4.3.24.RELEASE.jar;E:developermvnResponsityorgspringframeworkootspring-boot-autoconfigure1.5.21.RELEASEspring-boot-autoconfigure-1.5.21.RELEASE.jar;E:developermvnResponsityorgspringframeworkootspring-boot-starter-logging1.5.21.RELEASEspring-boot-starter-logging-1.5.21.RELEASE.jar;E:developermvnResponsitychqoslogbacklogback-classic1.1.11logback-classic-1.1.11.jar;E:developermvnResponsitychqoslogbacklogback-core1.1.11logback-core-1.1.11.jar;E:developermvnResponsityorgslf4jjcl-over-slf4j1.7.26jcl-over-slf4j-1.7.26.jar;E:developermvnResponsityorgslf4jjul-to-slf4j1.7.26jul-to-slf4j-1.7.26.jar;E:developermvnResponsityorgslf4jlog4j-over-slf4j1.7.26log4j-over-slf4j-1.7.26.jar;E:developermvnResponsityorgspringframeworkspring-core4.3.24.RELEASEspring-core-4.3.24.RELEASE.jar;E:developermvnResponsityorgyamlsnakeyaml1.17snakeyaml-1.17.jar;E:developermvnResponsityorgapachezookeeperzookeeper3.4.14zookeeper-3.4.14.jar;E:developermvnResponsityorgslf4jslf4j-api1.7.26slf4j-api-1.7.26.jar;E:developermvnResponsityorgslf4jslf4j-log4j121.7.26slf4j-log4j12-1.7.26.jar;E:developermvnResponsitycomgithubspotbugsspotbugs-annotations3.1.9spotbugs-annotations-3.1.9.jar;E:developermvnResponsitycomgooglecodefindbugsjsr3053.0.2jsr305-3.0.2.jar;E:developermvnResponsitylog4jlog4j1.2.17log4j-1.2.17.jar;E:developermvnResponsityjlinejline