什么是zookeeper
1.Zookeeper是一個分布式開源框架，提供了協調分布式應用的基本服務，它向外部應用暴露一組通用服務——分布式同步、命名服務、集群維護等，簡化分布式應用協調及其管理的難度，提供高性能的分布式服務。ZooKeeper本身可以以單機模式安裝運行，不過它的長處在於通過分布式ZooKeeper集群，基於一定的策略來保證ZooKeeper集群的穩定性和可用性，從而實現分布式應用的可靠性。
zookeeper運用場景
1.dubbo+zk實現rpc遠程調用中，zk在其中的作用類似springcloud中的eureka注冊服務中心,管理接口服務
2.發布訂閱
3.負載均衡
4.分布通知
5.分布式鎖
zokeeper存儲數據結構(類似xml數據結構)
在zk的節點中，每個節點名稱是不可以重復的（實現分布式鎖的關鍵性）,可以依次無限遞增。節點的類型可以分為四種：
1.持久節點，一旦創建就保存到硬盤上面
2.臨時節點，創建以后如果斷開連接則該節點自動刪除
3.順序持久節點
4.順序臨時節點
每個節點都可以通過節點事件監聽，對於節點的變化(增，刪，改)都能獲取到
例如：在使用zk作為dobbo注冊服務中心的時候
在Windows環境下安裝運行zk
1. 下載Windows版本zk，解壓以后,修改配置文件zoo_sample.cfg名字為zoo.cfg
2.在zk的bi目錄下找到zkServer.bat 啟動zk
3.在zk的bi目錄下找到zkCli 啟動zk的客戶端工具,可以在cmd里面對zk的節點進行創建 修改和刪除，可以根據zk的可視化管理工具進行查看,例如創建一個會員服務 ip地址是 127.0.0.1
可以通過ls 空格 / 查看當前的節點
JAVA如何操作Zookeeper
1.導入zookeeper所需要的依賴：
<dependency> <groupId>org.apache.zookeeper</groupId> <artifactId>zookeeper</artifactId> <version>3.4.14</version> </dependency>
2.編寫java類創建zookeeper的節點
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超時時間 */ 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) { // 獲取時間的狀態 KeeperState keeperState = event.getState(); EventType tventType = event.getType(); // 如果是建立連接 if (KeeperState.SyncConnected == keeperState) { if (EventType.None == tventType) { System.out.println("創建zk連接"); } } } }); zk.create("/zk", "testZookeeper".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT); System.out.println("創建節點成功"); zk.close(); } }
3.運行測試類，啟動zk服務,通過命令或者可視化客戶端查看生成的zk節點
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 創建zk連接 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 創建節點成功 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.在上述代碼中可能會出現一個問題 就是zk創建連接的時候 是一個異步操作，可以通過測試得知：
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超時時間 */ 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(); } // 獲取時間的狀態 KeeperState keeperState = event.getState(); EventType tventType = event.getType(); // 如果是建立連接 if (KeeperState.SyncConnected == keeperState) { if (EventType.None == tventType) { System.out.println("創建zk連接"); } } } }); zk.create("/zksyn", "testZookeeper".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT); System.out.println("創建節點成功"); zk.close(); } }
運行結果：
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 創建節點成功 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
從運行的結果可以看出，zk的創建是個異步過程，創建任務是新開了一條線程，從最后的打印日志也知道，新開的線程還是一條守護線程（主線程運行死亡，則自身死亡），所以 在zk的創建可能會出現 zk的連接還沒有創建成功，就已經開始創建節點，所以 這里最好要阻塞，保證 zk創建連接成功以后，才能創建zk節點，可以通過線程join來確定線程先后執行順序，也可以使用信號量CountDownLatch,每次執行類似i--操作，當值為0的時候 則不阻塞，其余狀態阻塞。修改以后的代碼：
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超時時間 */ private static final int SESSION_TIMEOUT = 5000; /** * 用於在zk創建連接的時候阻塞,不讓主程序往下運行 1表示初始值，每次調用則-1 等於0的時候 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(); } // 獲取時間的狀態 KeeperState keeperState = event.getState(); EventType tventType = event.getType(); // 如果是建立連接 if (KeeperState.SyncConnected == keeperState) { if (EventType.None == tventType) { System.out.println("等待6秒以后"); // 調用一次-1 countDownLatch.countDown(); } } } }); // 進行阻塞,等待，只有值為0的時候 才放行 countDownLatch.await(); String create = zk.create("/zksyn3", "testZookeeper".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT); System.out.println("創建節點成功" + 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 創建節點成功/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.關於創建zk節點的幾種類型：
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：表示路徑必須以"/" 開始
byte：創建節點的內容
acl：節點的記錄或者標記(訪問的權限該節點的)
createMode：節點的類型
public enum CreateMode { /** * The znode will not be automatically deleted upon client's disconnect. */ PERSISTENT (0, false, false),//持久節點 /** * 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),//有序持久節點 /** * The znode will be deleted upon the client's disconnect. */ EPHEMERAL (1, true, false),//臨時節點 /** * 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);//臨時有序節點
臨時節點在zk連接關閉斷開以后,則節點信息消失，以上就是簡單的java操作zookeeper的方式