zookeeper-分布式协调工具（一）,java操作zookeeper
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
package com.zk.demo; import java.io.IOException; 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; public class CreateZookeeper { /** * 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) throws IOException, InterruptedException, KeeperException { ZooKeeper zk = new ZooKeeper(CONNETTION_ADDR, SESSION_TIMEOUT, new Watcher() { public void process(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 16:18 GMT 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:\Java\jdk1.8.0_172\jre 15:37:24.268 [main] INFO org.apache.zookeeper.ZooKeeper - Client environment:java.class.path=E:\Java\jdk1.8.0_172\jre\lib\resources.jar;E:\Java\jdk1.8.0_172\jre\lib\rt.jar;E:\Java\jdk1.8.0_172\jre\lib\jsse.jar;E:\Java\jdk1.8.0_172\jre\lib\jce.jar;E:\Java\jdk1.8.0_172\jre\lib\charsets.jar;E:\Java\jdk1.8.0_172\jre\lib\jfr.jar;E:\Java\jdk1.8.0_172\jre\lib\ext\access-bridge-64.jar;E:\Java\jdk1.8.0_172\jre\lib\ext\cldrdata.jar;E:\Java\jdk1.8.0_172\jre\lib\ext\dnsns.jar;E:\Java\jdk1.8.0_172\jre\lib\ext\jaccess.jar;E:\Java\jdk1.8.0_172\jre\lib\ext\jfxrt.jar;E:\Java\jdk1.8.0_172\jre\lib\ext\localedata.jar;E:\Java\jdk1.8.0_172\jre\lib\ext\nashorn.jar;E:\Java\jdk1.8.0_172\jre\lib\ext\sunec.jar;E:\Java\jdk1.8.0_172\jre\lib\ext\sunjce_provider.jar;E:\Java\jdk1.8.0_172\jre\lib\ext\sunmscapi.jar;E:\Java\jdk1.8.0_172\jre\lib\ext\sunpkcs11.jar;E:\Java\jdk1.8.0_172\jre\lib\ext\zipfs.jar;E:\code\servlet\java-zk\target\classes;E:\code\servlet\java-zk\lib\zookeeper-3.4.14.jar;E:\developer\mvnResponsity\org\springframework\boot\spring-boot-starter\1.5.21.RELEASE\spring-boot-starter-1.5.21.RELEASE.jar;E:\developer\mvnResponsity\org\springframework\boot\spring-boot\1.5.21.RELEASE\spring-boot-1.5.21.RELEASE.jar;E:\developer\mvnResponsity\org\springframework\spring-context\4.3.24.RELEASE\spring-context-4.3.24.RELEASE.jar;E:\developer\mvnResponsity\org\springframework\spring-aop\4.3.24.RELEASE\spring-aop-4.3.24.RELEASE.jar;E:\developer\mvnResponsity\org\springframework\spring-beans\4.3.24.RELEASE\spring-beans-4.3.24.RELEASE.jar;E:\developer\mvnResponsity\org\springframework\spring-expression\4.3.24.RELEASE\spring-expression-4.3.24.RELEASE.jar;E:\developer\mvnResponsity\org\springframework\boot\spring-boot-autoconfigure\1.5.21.RELEASE\spring-boot-autoconfigure-1.5.21.RELEASE.jar;E:\developer\mvnResponsity\org\springframework\boot\spring-boot-starter-logging\1.5.21.RELEASE\spring-boot-starter-logging-1.5.21.RELEASE.jar;E:\developer\mvnResponsity\ch\qos\logback\logback-classic\1.1.11\logback-classic-1.1.11.jar;E:\developer\mvnResponsity\ch\qos\logback\logback-core\1.1.11\logback-core-1.1.11.jar;E:\developer\mvnResponsity\org\slf4j\jcl-over-slf4j\1.7.26\jcl-over-slf4j-1.7.26.jar;E:\developer\mvnResponsity\org\slf4j\jul-to-slf4j\1.7.26\jul-to-slf4j-1.7.26.jar;E:\developer\mvnResponsity\org\slf4j\log4j-over-slf4j\1.7.26\log4j-over-slf4j-1.7.26.jar;E:\developer\mvnResponsity\org\springframework\spring-core\4.3.24.RELEASE\spring-core-4.3.24.RELEASE.jar;E:\developer\mvnResponsity\org\yaml\snakeyaml\1.17\snakeyaml-1.17.jar;E:\developer\mvnResponsity\org\apache\zookeeper\zookeeper\3.4.14\zookeeper-3.4.14.jar;E:\developer\mvnResponsity\org\slf4j\slf4j-api\1.7.26\slf4j-api-1.7.26.jar;E:\developer\mvnResponsity\org\slf4j\slf4j-log4j12\1.7.26\slf4j-log4j12-1.7.26.jar;E:\developer\mvnResponsity\com\github\spotbugs\spotbugs-annotations\3.1.9\spotbugs-annotations-3.1.9.jar;E:\developer\mvnResponsity\com\google\code\findbugs\jsr305\3.0.2\jsr305-3.0.2.jar;E:\developer\mvnResponsity\log4j\log4j\1.2.17\log4j-1.2.17.jar;E:\developer\mvnResponsity\jline\jline\0.9.94\jline-0.9.94.jar;E:\developer\mvnResponsity\org\apache\yetus\audience-annotations\0.5.0\audience-annotations-0.5.0.jar;E:\developer\mvnResponsity\io\netty\netty\3.10.6.Final\netty-3.10.6.Final.jar 15:37:24.268 [main] INFO org.apache.zookeeper.ZooKeeper - Client environment:java.library.path=E:\Java\jdk1.8.0_172\bin;C:\Windows\Sun\Java\bin;C:\Windows\system32;C:\Windows;E:/Java/jdk1.8.0_172/jre/bin/server;E:/Java/jdk1.8.0_172/jre/bin;E:/Java/jdk1.8.0_172/jre/lib/amd64;E:\xftp\;C:\Windows\system32;C:\Windows;C:\Windows\System32\Wbem;C:\Windows\System32\WindowsPowerShell\v1.0\;E:\Java\jdk1.8.0_172\lib;E:\Java\jdk1.8.0_172\jre\bin;E:\maven\apache-maven-3.5.3\bin;E:\software\mysql\mysql-8.0.15-winx64;C:\Users\Administrator\AppData\Local\Microsoft\WindowsApps;;E:\sts\spring-tool-suite-3.9.4.RELEASE-e4.7.3a-win32-x86_64\sts-bundle\sts-3.9.4.RELEASE;;. 15:37:24.269 [main] INFO org.apache.zookeeper.ZooKeeper - Client environment:java.io.tmpdir=C:\Users\ADMINI~1\AppData\Local\Temp\ 15:37:24.269 [main] INFO org.apache.zookeeper.ZooKeeper - Client environment:java.compiler=<NA> 15:37:24.269 [main] INFO org.apache.zookeeper.ZooKeeper - Client environment:os.name=Windows 10 15:37:24.269 [main] INFO org.apache.zookeeper.ZooKeeper - Client environment:os.arch=amd64 15:37:24.269 [main] INFO org.apache.zookeeper.ZooKeeper - Client environment:os.version=10.0 15:37:24.269 [main] INFO org.apache.zookeeper.ZooKeeper - Client environment:user.name=Administrator 15:37:24.269 [main] INFO org.apache.zookeeper.ZooKeeper - Client environment:user.home=C:\Users\Administrator 15:37:24.269 [main] INFO org.apache.zookeeper.ZooKeeper - Client environment:user.dir=E:\code\servlet\java-zk 15:37:24.270 [main] INFO org.apache.zookeeper.ZooKeeper - Initiating client connection, connectString=127.0.0.1:2181 sessionTimeout=5000 watcher=com.zk.demo.CreateZookeeper$1@6d21714c 15:37:24.272 [main] DEBUG org.apache.zookeeper.ClientCnxn - zookeeper.disableAutoWatchReset is false 15:37:24.393 [main-SendThread(127.0.0.1:2181)] DEBUG org.apache.zookeeper.SaslServerPrincipal - Canonicalized address to 127.0.0.1 15:37:24.395 [main-SendThread(127.0.0.1:2181)] INFO org.apache.zookeeper.ClientCnxn - Opening socket connection to server 127.0.0.1/127.0.0.1:2181. Will not attempt to authenticate using SASL (unknown error) 15:37:24.396 [main-SendThread(127.0.0.1:2181)] INFO org.apache.zookeeper.ClientCnxn - Socket connection established to 127.0.0.1/127.0.0.1:2181, initiating session 15:37:24.397 [main-SendThread(127.0.0.1:2181)] DEBUG org.apache.zookeeper.ClientCnxn - Session establishment request sent on 127.0.0.1/127.0.0.1:2181 15:37:24.401 [main-SendThread(127.0.0.1:2181)] WARN org.apache.zookeeper.ClientCnxnSocket - Connected to an old server; r-o mode will be unavailable 15:37:24.401 [main-SendThread(127.0.0.1:2181)] INFO org.apache.zookeeper.ClientCnxn - Session establishment complete on server 127.0.0.1/127.0.0.1:2181, sessionid = 0x16b07ab1dee0002, negotiated timeout = 5000 创建zk连接 15:37:24.407 [main-SendThread(127.0.0.1:2181)] DEBUG org.apache.zookeeper.ClientCnxn - Reading reply sessionid:0x16b07ab1dee0002, packet:: clientPath:null serverPath:null finished:false header:: 1,1 replyHeader:: 1,62,0 request:: '/zk,#746573745a6f6f6b6565706572,v{s{31,s{'world,'anyone}}},0 response:: '/zk 创建节点成功 15:37:24.407 [main] DEBUG org.apache.zookeeper.ZooKeeper - Closing session: 0x16b07ab1dee0002 15:37:24.407 [main] DEBUG org.apache.zookeeper.ClientCnxn - Closing client for session: 0x16b07ab1dee0002 15:37:24.410 [main-SendThread(127.0.0.1:2181)] DEBUG org.apache.zookeeper.ClientCnxn - Reading reply sessionid:0x16b07ab1dee0002, packet:: clientPath:null serverPath:null finished:false header:: 2,-11 replyHeader:: 2,63,0 request:: null response:: null 15:37:24.410 [main] DEBUG org.apache.zookeeper.ClientCnxn - Disconnecting client for session: 0x16b07ab1dee0002 15:37:24.410 [main] INFO org.apache.zookeeper.ZooKeeper - Session: 0x16b07ab1dee0002 closed 15:37:24.411 [main-EventThread] INFO org.apache.zookeeper.ClientCnxn - EventThread shut down for session: 0x16b07ab1dee0002
4.在上述代码中可能会出现一个问题 就是zk创建连接的时候 是一个异步操作，可以通过测试得知：
package com.zk.demo; import java.io.IOException; 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; public class CreateZookeeper { /** * 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) throws IOException, InterruptedException, KeeperException { ZooKeeper zk = new ZooKeeper(CONNETTION_ADDR, SESSION_TIMEOUT, new Watcher() { public void process(WatchedEvent event) { try { //休眠6秒 Thread.sleep(6000); } catch (InterruptedException e) { e.printStackTrace(); } // 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("/zksyn", "testZookeeper".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT); System.out.println("创建节点成功"); zk.close(); } }
运行结果：
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] 15:49:00.264 [main] INFO org.apache.zookeeper.ZooKeeper - Client environment:zookeeper.version=3.4.14-4c25d480e66aadd371de8bd2fd8da255ac140bcf, built on 03/06/2019 16:18 GMT 15:49:00.266 [main] INFO org.apache.zookeeper.ZooKeeper - Client environment:host.name=NNH1J2ASSQP10BA 15:49:00.266 [main] INFO org.apache.zookeeper.ZooKeeper - Client environment:java.version=1.8.0_172 15:49:00.266 [main] INFO org.apache.zookeeper.ZooKeeper - Client environment:java.vendor=Oracle Corporation 15:49:00.266 [main] INFO org.apache.zookeeper.ZooKeeper - Client environment:java.home=E:\Java\jdk1.8.0_172\jre 15:49:00.266 [main] INFO org.apache.zookeeper.ZooKeeper - Client environment:java.class.path=E:\Java\jdk1.8.0_172\jre\lib\resources.jar;E:\Java\jdk1.8.0_172\jre\lib\rt.jar;E:\Java\jdk1.8.0_172\jre\lib\jsse.jar;E:\Java\jdk1.8.0_172\jre\lib\jce.jar;E:\Java\jdk1.8.0_172\jre\lib\charsets.jar;E:\Java\jdk1.8.0_172\jre\lib\jfr.jar;E:\Java\jdk1.8.0_172\jre\lib\ext\access-bridge-64.jar;E:\Java\jdk1.8.0_172\jre\lib\ext\cldrdata.jar;E:\Java\jdk1.8.0_172\jre\lib\ext\dnsns.jar;E:\Java\jdk1.8.0_172\jre\lib\ext\jaccess.jar;E:\Java\jdk1.8.0_172\jre\lib\ext\jfxrt.jar;E:\Java\jdk1.8.0_172\jre\lib\ext\localedata.jar;E:\Java\jdk1.8.0_172\jre\lib\ext\nashorn.jar;E:\Java\jdk1.8.0_172\jre\lib\ext\sunec.jar;E:\Java\jdk1.8.0_172\jre\lib\ext\sunjce_provider.jar;E:\Java\jdk1.8.0_172\jre\lib\ext\sunmscapi.jar;E:\Java\jdk1.8.0_172\jre\lib\ext\sunpkcs11.jar;E:\Java\jdk1.8.0_172\jre\lib\ext\zipfs.jar;E:\code\servlet\java-zk\target\classes;E:\code\servlet\java-zk\lib\zookeeper-3.4.14.jar;E:\developer\mvnResponsity\org\springframework\boot\spring-boot-starter\1.5.21.RELEASE\spring-boot-starter-1.5.21.RELEASE.jar;E:\developer\mvnResponsity\org\springframework\boot\spring-boot\1.5.21.RELEASE\spring-boot-1.5.21.RELEASE.jar;E:\developer\mvnResponsity\org\springframework\spring-context\4.3.24.RELEASE\spring-context-4.3.24.RELEASE.jar;E:\developer\mvnResponsity\org\springframework\spring-aop\4.3.24.RELEASE\spring-aop-4.3.24.RELEASE.jar;E:\developer\mvnResponsity\org\springframework\spring-beans\4.3.24.RELEASE\spring-beans-4.3.24.RELEASE.jar;E:\developer\mvnResponsity\org\springframework\spring-expression\4.3.24.RELEASE\spring-expression-4.3.24.RELEASE.jar;E:\developer\mvnResponsity\org\springframework\boot\spring-boot-autoconfigure\1.5.21.RELEASE\spring-boot-autoconfigure-1.5.21.RELEASE.jar;E:\developer\mvnResponsity\org\springframework\boot\spring-boot-starter-logging\1.5.21.RELEASE\spring-boot-starter-logging-1.5.21.RELEASE.jar;E:\developer\mvnResponsity\ch\qos\logback\logback-classic\1.1.11\logback-classic-1.1.11.jar;E:\developer\mvnResponsity\ch\qos\logback\logback-core\1.1.11\logback-core-1.1.11.jar;E:\developer\mvnResponsity\org\slf4j\jcl-over-slf4j\1.7.26\jcl-over-slf4j-1.7.26.jar;E:\developer\mvnResponsity\org\slf4j\jul-to-slf4j\1.7.26\jul-to-slf4j-1.7.26.jar;E:\developer\mvnResponsity\org\slf4j\log4j-over-slf4j\1.7.26\log4j-over-slf4j-1.7.26.jar;E:\developer\mvnResponsity\org\springframework\spring-core\4.3.24.RELEASE\spring-core-4.3.24.RELEASE.jar;E:\developer\mvnResponsity\org\yaml\snakeyaml\1.17\snakeyaml-1.17.jar;E:\developer\mvnResponsity\org\apache\zookeeper\zookeeper\3.4.14\zookeeper-3.4.14.jar;E:\developer\mvnResponsity\org\slf4j\slf4j-api\1.7.26\slf4j-api-1.7.26.jar;E:\developer\mvnResponsity\org\slf4j\slf4j-log4j12\1.7.26\slf4j-log4j12-1.7.26.jar;E:\developer\mvnResponsity\com\github\spotbugs\spotbugs-annotations\3.1.9\spotbugs-annotations-3.1.9.jar;E:\developer\mvnResponsity\com\google\code\findbugs\jsr305\3.0.2\jsr305-3.0.2.jar;E:\developer\mvnResponsity\log4j\log4j\1.2.17\log4j-1.2.17.jar;E:\developer\mvnResponsity\jline\jline\0.9.94\jline-0.9.94.jar;E:\developer\mvnResponsity\org\apache\yetus\audience-annotations\0.5.0\audience-annotations-0.5.0.jar;E:\developer\mvnResponsity\io\netty\netty\3.10.6.Final\netty-3.10.6.Final.jar 15:49:00.266 [main] INFO org.apache.zookeeper.ZooKeeper - Client environment:java.library.path=E:\Java\jdk1.8.0_172\bin;C:\Windows\Sun\Java\bin;C:\Windows\system32;C:\Windows;E:/Java/jdk1.8.0_172/jre/bin/server;E:/Java/jdk1.8.0_172/jre/bin;E:/Java/jdk1.8.0_172/jre/lib/amd64;E:\xftp\;C:\Windows\system32;C:\Windows;C:\Windows\System32\Wbem;C:\Windows\System32\WindowsPowerShell\v1.0\;E:\Java\jdk1.8.0_172\lib;E:\Java\jdk1.8.0_172\jre\bin;E:\maven\apache-maven-3.5.3\bin;E:\software\mysql\mysql-8.0.15-winx64;C:\Users\Administrator\AppData\Local\Microsoft\WindowsApps;;E:\sts\spring-tool-suite-3.9.4.RELEASE-e4.7.3a-win32-x86_64\sts-bundle\sts-3.9.4.RELEASE;;. 15:49:00.266 [main] INFO org.apache.zookeeper.ZooKeeper - Client environment:java.io.tmpdir=C:\Users\ADMINI~1\AppData\Local\Temp\ 15:49:00.266 [main] INFO org.apache.zookeeper.ZooKeeper - Client environment:java.compiler=<NA> 15:49:00.266 [main] INFO org.apache.zookeeper.ZooKeeper - Client environment:os.name=Windows 10 15:49:00.266 [main] INFO org.apache.zookeeper.ZooKeeper - Client environment:os.arch=amd64 15:49:00.266 [main] INFO org.apache.zookeeper.ZooKeeper - Client environment:os.version=10.0 15:49:00.266 [main] INFO org.apache.zookeeper.ZooKeeper - Client environment:user.name=Administrator 15:49:00.266 [main] INFO org.apache.zookeeper.ZooKeeper - Client environment:user.home=C:\Users\Administrator 15:49:00.266 [main] INFO org.apache.zookeeper.ZooKeeper - Client environment:user.dir=E:\code\servlet\java-zk 15:49:00.267 [main] INFO org.apache.zookeeper.ZooKeeper - Initiating client connection, connectString=127.0.0.1:2181 sessionTimeout=5000 watcher=com.zk.demo.CreateZookeeper$1@6d21714c 15:49:00.269 [main] DEBUG org.apache.zookeeper.ClientCnxn - zookeeper.disableAutoWatchReset is false 15:49:00.381 [main-SendThread(127.0.0.1:2181)] DEBUG org.apache.zookeeper.SaslServerPrincipal - Canonicalized address to 127.0.0.1 15:49:00.383 [main-SendThread(127.0.0.1:2181)] INFO org.apache.zookeeper.ClientCnxn - Opening socket connection to server 127.0.0.1/127.0.0.1:2181. Will not attempt to authenticate using SASL (unknown error) 15:49:00.384 [main-SendThread(127.0.0.1:2181)] INFO org.apache.zookeeper.ClientCnxn - Socket connection established to 127.0.0.1/127.0.0.1:2181, initiating session 15:49:00.385 [main-SendThread(127.0.0.1:2181)] DEBUG org.apache.zookeeper.ClientCnxn - Session establishment request sent on 127.0.0.1/127.0.0.1:2181 15:49:00.399 [main-SendThread(127.0.0.1:2181)] WARN org.apache.zookeeper.ClientCnxnSocket - Connected to an old server; r-o mode will be unavailable 15:49:00.399 [main-SendThread(127.0.0.1:2181)] INFO org.apache.zookeeper.ClientCnxn - Session establishment complete on server 127.0.0.1/127.0.0.1:2181, sessionid = 0x16b07ab1dee0005, negotiated timeout = 5000 15:49:00.403 [main-SendThread(127.0.0.1:2181)] DEBUG org.apache.zookeeper.ClientCnxn - Reading reply sessionid:0x16b07ab1dee0005, packet:: clientPath:null serverPath:null finished:false header:: 1,1 replyHeader:: 1,71,0 request:: '/zksyn,#746573745a6f6f6b6565706572,v{s{31,s{'world,'anyone}}},0 response:: '/zksyn 创建节点成功 15:49:00.404 [main] DEBUG org.apache.zookeeper.ZooKeeper - Closing session: 0x16b07ab1dee0005 15:49:00.404 [main] DEBUG org.apache.zookeeper.ClientCnxn - Closing client for session: 0x16b07ab1dee0005 15:49:00.406 [main-SendThread(127.0.0.1:2181)] DEBUG org.apache.zookeeper.ClientCnxn - Reading reply sessionid:0x16b07ab1dee0005, packet:: clientPath:null serverPath:null finished:false header:: 2,-11 replyHeader:: 2,72,0 request:: null response:: null 15:49:00.406 [main] DEBUG org.apache.zookeeper.ClientCnxn - Disconnecting client for session: 0x16b07ab1dee0005 15:49:00.406 [main] INFO org.apache.zookeeper.ZooKeeper - Session: 0x16b07ab1dee0005 closed
从运行的结果可以看出，zk的创建是个异步过程，创建任务是新开了一条线程，从最后的打印日志也知道，新开的线程还是一条守护线程（主线程运行死亡，则自身死亡），所以 在zk的创建可能会出现 zk的连接还没有创建成功，就已经开始创建节点，所以 这里最好要阻塞，保证 zk创建连接成功以后，才能创建zk节点，可以通过线程join来确定线程先后执行顺序，也可以使用信号量CountDownLatch,每次执行类似i--操作，当值为0的时候 则不阻塞，其余状态阻塞。修改以后的代码：
package com.zk.demo; 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; public class CreateZookeeper { /** * 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; /** * 用于在zk创建连接的时候阻塞,不让主程序往下运行 1表示初始值，每次调用则-1 等于0的时候 取消阻塞 */ private static final CountDownLatch countDownLatch = new CountDownLatch(1); public static void main(String[] args) throws IOException, InterruptedException, KeeperException { ZooKeeper zk = new ZooKeeper(CONNETTION_ADDR, SESSION_TIMEOUT, new Watcher() { public void process(WatchedEvent event) { try { // 休眠6秒 Thread.sleep(6000); } catch (InterruptedException e) { e.printStackTrace(); } // 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("等待6秒以后"); // 调用一次-1 countDownLatch.countDown(); } } } }); // 进行阻塞,等待，只有值为0的时候 才放行 countDownLatch.await(); String create = zk.create("/zksyn3", "testZookeeper".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT); System.out.println("创建节点成功" + create); zk.close(); } }
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] 16:01:38.559 [main] INFO org.apache.zookeeper.ZooKeeper - Client environment:zookeeper.version=3.4.14-4c25d480e66aadd371de8bd2fd8da255ac140bcf, built on 03/06/2019 16:18 GMT 16:01:38.560 [main] INFO org.apache.zookeeper.ZooKeeper - Client environment:host.name=NNH1J2ASSQP10BA 16:01:38.560 [main] INFO org.apache.zookeeper.ZooKeeper - Client environment:java.version=1.8.0_172 16:01:38.561 [main] INFO org.apache.zookeeper.ZooKeeper - Client environment:java.vendor=Oracle Corporation 16:01:38.561 [main] INFO org.apache.zookeeper.ZooKeeper - Client environment:java.home=E:\Java\jdk1.8.0_172\jre 16:01:38.561 [main] INFO org.apache.zookeeper.ZooKeeper - Client environment:java.class.path=E:\Java\jdk1.8.0_172\jre\lib\resources.jar;E:\Java\jdk1.8.0_172\jre\lib\rt.jar;E:\Java\jdk1.8.0_172\jre\lib\jsse.jar;E:\Java\jdk1.8.0_172\jre\lib\jce.jar;E:\Java\jdk1.8.0_172\jre\lib\charsets.jar;E:\Java\jdk1.8.0_172\jre\lib\jfr.jar;E:\Java\jdk1.8.0_172\jre\lib\ext\access-bridge-64.jar;E:\Java\jdk1.8.0_172\jre\lib\ext\cldrdata.jar;E:\Java\jdk1.8.0_172\jre\lib\ext\dnsns.jar;E:\Java\jdk1.8.0_172\jre\lib\ext\jaccess.jar;E:\Java\jdk1.8.0_172\jre\lib\ext\jfxrt.jar;E:\Java\jdk1.8.0_172\jre\lib\ext\localedata.jar;E:\Java\jdk1.8.0_172\jre\lib\ext\nashorn.jar;E:\Java\jdk1.8.0_172\jre\lib\ext\sunec.jar;E:\Java\jdk1.8.0_172\jre\lib\ext\sunjce_provider.jar;E:\Java\jdk1.8.0_172\jre\lib\ext\sunmscapi.jar;E:\Java\jdk1.8.0_172\jre\lib\ext\sunpkcs11.jar;E:\Java\jdk1.8.0_172\jre\lib\ext\zipfs.jar;E:\code\servlet\java-zk\target\classes;E:\code\servlet\java-zk\lib\zookeeper-3.4.14.jar;E:\developer\mvnResponsity\org\springframework\boot\spring-boot-starter\1.5.21.RELEASE\spring-boot-starter-1.5.21.RELEASE.jar;E:\developer\mvnResponsity\org\springframework\boot\spring-boot\1.5.21.RELEASE\spring-boot-1.5.21.RELEASE.jar;E:\developer\mvnResponsity\org\springframework\spring-context\4.3.24.RELEASE\spring-context-4.3.24.RELEASE.jar;E:\developer\mvnResponsity\org\springframework\spring-aop\4.3.24.RELEASE\spring-aop-4.3.24.RELEASE.jar;E:\developer\mvnResponsity\org\springframework\spring-beans\4.3.24.RELEASE\spring-beans-4.3.24.RELEASE.jar;E:\developer\mvnResponsity\org\springframework\spring-expression\4.3.24.RELEASE\spring-expression-4.3.24.RELEASE.jar;E:\developer\mvnResponsity\org\springframework\boot\spring-boot-autoconfigure\1.5.21.RELEASE\spring-boot-autoconfigure-1.5.21.RELEASE.jar;E:\developer\mvnResponsity\org\springframework\boot\spring-boot-starter-logging\1.5.21.RELEASE\spring-boot-starter-logging-1.5.21.RELEASE.jar;E:\developer\mvnResponsity\ch\qos\logback\logback-classic\1.1.11\logback-classic-1.1.11.jar;E:\developer\mvnResponsity\ch\qos\logback\logback-core\1.1.11\logback-core-1.1.11.jar;E:\developer\mvnResponsity\org\slf4j\jcl-over-slf4j\1.7.26\jcl-over-slf4j-1.7.26.jar;E:\developer\mvnResponsity\org\slf4j\jul-to-slf4j\1.7.26\jul-to-slf4j-1.7.26.jar;E:\developer\mvnResponsity\org\slf4j\log4j-over-slf4j\1.7.26\log4j-over-slf4j-1.7.26.jar;E:\developer\mvnResponsity\org\springframework\spring-core\4.3.24.RELEASE\spring-core-4.3.24.RELEASE.jar;E:\developer\mvnResponsity\org\yaml\snakeyaml\1.17\snakeyaml-1.17.jar;E:\developer\mvnResponsity\org\apache\zookeeper\zookeeper\3.4.14\zookeeper-3.4.14.jar;E:\developer\mvnResponsity\org\slf4j\slf4j-api\1.7.26\slf4j-api-1.7.26.jar;E:\developer\mvnResponsity\org\slf4j\slf4j-log4j12\1.7.26\slf4j-log4j12-1.7.26.jar;E:\developer\mvnResponsity\com\github\spotbugs\spotbugs-annotations\3.1.9\spotbugs-annotations-3.1.9.jar;E:\developer\mvnResponsity\com\google\code\findbugs\jsr305\3.0.2\jsr305-3.0.2.jar;E:\developer\mvnResponsity\log4j\log4j\1.2.17\log4j-1.2.17.jar;E:\developer\mvnResponsity\jline\jline\0.9.94\jline-0.9.94.jar;E:\developer\mvnResponsity\org\apache\yetus\audience-annotations\0.5.0\audience-annotations-0.5.0.jar;E:\developer\mvnResponsity\io\netty\netty\3.10.6.Final\netty-3.10.6.Final.jar 16:01:38.561 [main] INFO org.apache.zookeeper.ZooKeeper - Client environment:java.library.path=E:\Java\jdk1.8.0_172\bin;C:\Windows\Sun\Java\bin;C:\Windows\system32;C:\Windows;E:/Java/jdk1.8.0_172/jre/bin/server;E:/Java/jdk1.8.0_172/jre/bin;E:/Java/jdk1.8.0_172/jre/lib/amd64;E:\xftp\;C:\Windows\system32;C:\Windows;C:\Windows\System32\Wbem;C:\Windows\System32\WindowsPowerShell\v1.0\;E:\Java\jdk1.8.0_172\lib;E:\Java\jdk1.8.0_172\jre\bin;E:\maven\apache-maven-3.5.3\bin;E:\software\mysql\mysql-8.0.15-winx64;C:\Users\Administrator\AppData\Local\Microsoft\WindowsApps;;E:\sts\spring-tool-suite-3.9.4.RELEASE-e4.7.3a-win32-x86_64\sts-bundle\sts-3.9.4.RELEASE;;. 16:01:38.561 [main] INFO org.apache.zookeeper.ZooKeeper - Client environment:java.io.tmpdir=C:\Users\ADMINI~1\AppData\Local\Temp\ 16:01:38.561 [main] INFO org.apache.zookeeper.ZooKeeper - Client environment:java.compiler=<NA> 16:01:38.561 [main] INFO org.apache.zookeeper.ZooKeeper - Client environment:os.name=Windows 10 16:01:38.561 [main] INFO org.apache.zookeeper.ZooKeeper - Client environment:os.arch=amd64 16:01:38.561 [main] INFO org.apache.zookeeper.ZooKeeper - Client environment:os.version=10.0 16:01:38.561 [main] INFO org.apache.zookeeper.ZooKeeper - Client environment:user.name=Administrator 16:01:38.561 [main] INFO org.apache.zookeeper.ZooKeeper - Client environment:user.home=C:\Users\Administrator 16:01:38.561 [main] INFO org.apache.zookeeper.ZooKeeper - Client environment:user.dir=E:\code\servlet\java-zk 16:01:38.562 [main] INFO org.apache.zookeeper.ZooKeeper - Initiating client connection, connectString=127.0.0.1:2181 sessionTimeout=5000 watcher=com.zk.demo.CreateZookeeper$1@6d21714c 16:01:38.564 [main] DEBUG org.apache.zookeeper.ClientCnxn - zookeeper.disableAutoWatchReset is false 16:01:38.677 [main-SendThread(127.0.0.1:2181)] DEBUG org.apache.zookeeper.SaslServerPrincipal - Canonicalized address to 127.0.0.1 16:01:38.679 [main-SendThread(127.0.0.1:2181)] INFO org.apache.zookeeper.ClientCnxn - Opening socket connection to server 127.0.0.1/127.0.0.1:2181. Will not attempt to authenticate using SASL (unknown error) 16:01:38.680 [main-SendThread(127.0.0.1:2181)] INFO org.apache.zookeeper.ClientCnxn - Socket connection established to 127.0.0.1/127.0.0.1:2181, initiating session 16:01:38.681 [main-SendThread(127.0.0.1:2181)] DEBUG org.apache.zookeeper.ClientCnxn - Session establishment request sent on 127.0.0.1/127.0.0.1:2181 16:01:38.694 [main-SendThread(127.0.0.1:2181)] WARN org.apache.zookeeper.ClientCnxnSocket - Connected to an old server; r-o mode will be unavailable 16:01:38.695 [main-SendThread(127.0.0.1:2181)] INFO org.apache.zookeeper.ClientCnxn - Session establishment complete on server 127.0.0.1/127.0.0.1:2181, sessionid = 0x16b07ab1dee0008, negotiated timeout = 5000 16:01:40.352 [main-SendThread(127.0.0.1:2181)] DEBUG org.apache.zookeeper.ClientCnxn - Got ping response for sessionid: 0x16b07ab1dee0008 after 1ms 16:01:42.017 [main-SendThread(127.0.0.1:2181)] DEBUG org.apache.zookeeper.ClientCnxn - Got ping response for sessionid: 0x16b07ab1dee0008 after 0ms 16:01:43.684 [main-SendThread(127.0.0.1:2181)] DEBUG org.apache.zookeeper.ClientCnxn - Got ping response for sessionid: 0x16b07ab1dee0008 after 0ms 等待6秒以后 16:01:44.710 [main-SendThread(127.0.0.1:2181)] DEBUG org.apache.zookeeper.ClientCnxn - Reading reply sessionid:0x16b07ab1dee0008, packet:: clientPath:null serverPath:null finished:false header:: 1,1 replyHeader:: 1,80,0 request:: '/zksyn3,#746573745a6f6f6b6565706572,v{s{31,s{'world,'anyone}}},0 response:: '/zksyn3 创建节点成功/zksyn3 16:01:44.711 [main-SendThread(127.0.0.1:2181)] DEBUG org.apache.zookeeper.ClientCnxn - Got ping response for sessionid: 0x16b07ab1dee0008 after 12ms 16:01:44.711 [main] DEBUG org.apache.zookeeper.ZooKeeper - Closing session: 0x16b07ab1dee0008 16:01:44.711 [main] DEBUG org.apache.zookeeper.ClientCnxn - Closing client for session: 0x16b07ab1dee0008 16:01:44.713 [main-SendThread(127.0.0.1:2181)] DEBUG org.apache.zookeeper.ClientCnxn - Reading reply sessionid:0x16b07ab1dee0008, packet:: clientPath:null serverPath:null finished:false header:: 2,-11 replyHeader:: 2,81,0 request:: null response:: null 16:01:44.713 [main] DEBUG org.apache.zookeeper.ClientCnxn - Disconnecting client for session: 0x16b07ab1dee0008 16:01:44.713 [main] INFO org.apache.zookeeper.ZooKeeper - Session: 0x16b07ab1dee0008 closed 16:01:44.713 [main-EventThread] INFO org.apache.zookeeper.ClientCnxn - EventThread shut down for session: 0x16b07ab1dee0008
5.关于创建zk节点的几种类型：
String create = zk.create("/zksyn3", "testZookeeper".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
public String create(final String path, byte data[], List<ACL> acl, CreateMode createMode) throws KeeperException, InterruptedException { final String clientPath = path; PathUtils.validatePath(clientPath, createMode.isSequential()); final String serverPath = prependChroot(clientPath); RequestHeader h = new RequestHeader(); h.setType(ZooDefs.OpCode.create); CreateRequest request = new CreateRequest(); CreateResponse response = new CreateResponse(); request.setData(data); request.setFlags(createMode.toFlag()); request.setPath(serverPath); if (acl != null && acl.size() == 0) { throw new KeeperException.InvalidACLException(); } request.setAcl(acl); ReplyHeader r = cnxn.submitRequest(h, request, response, null); if (r.getErr() != 0) { throw KeeperException.create(KeeperException.Code.get(r.getErr()), clientPath); } if (cnxn.chrootPath == null) { return response.getPath(); } else { return response.getPath().substring(cnxn.chrootPath.length()); } }
path：表示路径必须以"/" 开始
byte：创建节点的内容
acl：节点的记录或者标记(访问的权限该节点的)
createMode：节点的类型
public enum CreateMode { /** * The znode will not be automatically deleted upon client's disconnect. */ PERSISTENT (0, false, false),//持久节点 /** * The znode will not be automatically deleted upon client's disconnect, * and its name will be appended with a monotonically increasing number. */ PERSISTENT_SEQUENTIAL (2, false, true),//有序持久节点 /** * The znode will be deleted upon the client's disconnect. */ EPHEMERAL (1, true, false),//临时节点 /** * The znode will be deleted upon the client's disconnect, and its name * will be appended with a monotonically increasing number. */ EPHEMERAL_SEQUENTIAL (3, true, true);//临时有序节点
临时节点在zk连接关闭断开以后,则节点信息消失，以上就是简单的java操作zookeeper的方式
