Good Zookeeper Tutorial with Java client

参考： https://stackoverflow.com/questions/33524537/good-zookeeper-tutorial-with-java-client

I was trying to use Zookeeper in our project. Could run the server..Even test it using zkcli.sh .. All good.. But couldn't find a good tutorial for me to connect to this server using Java ! All I need in Java API is a method

 

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Finally, this is the simplest and most basic program I came up with which will help you with ZooKeeper "Getting Started":

package com.fly.app;

import java.util.Date;
import java.util.List;
import java.util.concurrent.CountDownLatch;

import org.apache.zookeeper.CreateMode;
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;

public class ZkConnect {
    private ZooKeeper zk;
    private CountDownLatch connSignal = new CountDownLatch(0);

    //host should be 127.0.0.1:3000,127.0.0.1:3001,127.0.0.1:3002
    public ZooKeeper connect(String host) throws Exception {
        zk = new ZooKeeper(host, 3000, new Watcher() {
            public void process(WatchedEvent event) {
                if (event.getState() == KeeperState.SyncConnected) {
                    connSignal.countDown();
                }
            }
        });
        connSignal.await();
        return zk;
    }

    public void close() throws InterruptedException {
        zk.close();
    }

    public void createNode(String path, byte[] data) throws Exception
    {
        zk.create(path, data, Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
    }

    public void updateNode(String path, byte[] data) throws Exception
    {
        zk.setData(path, data, zk.exists(path, true).getVersion());
    }

    public void deleteNode(String path) throws Exception
    {
        zk.delete(path,  zk.exists(path, true).getVersion());
    }

    public static void main (String args[]) throws Exception
    {
        ZkConnect connector = new ZkConnect();
        ZooKeeper zk = connector.connect("54.169.132.0,52.74.51.0");
        String newNode = "/deepakDate"+new Date();
        connector.createNode(newNode, new Date().toString().getBytes());
        List<String> zNodes = zk.getChildren("/", true);
        for (String zNode: zNodes)
        {
           System.out.println("ChildrenNode " + zNode);   
        }
        byte[] data = zk.getData(newNode, true, zk.exists(newNode, true));
        System.out.println("GetData before setting");
        for ( byte dataPoint : data)
        {
            System.out.print ((char)dataPoint);
        }

        System.out.println("GetData after setting");
        connector.updateNode(newNode, "Modified data".getBytes());
        data = zk.getData(newNode, true, zk.exists(newNode, true));
        for ( byte dataPoint : data)
        {
            System.out.print ((char)dataPoint);
        }
        connector.deleteNode(newNode);
    }

}

　　pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.fly.app</groupId>
    <artifactId>new-app</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>
    <name>new-app</name>
    <url>http://maven.apache.org</url>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>1.6</maven.compiler.source>
        <maven.compiler.target>1.6</maven.compiler.target>

    </properties>

    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>3.8.1</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.apache.zookeeper</groupId>
            <artifactId>zookeeper</artifactId>
            <version>3.4.6</version>
        </dependency>
    </dependencies>
<build>
    <plugins>
       <plugin>
           <groupId>org.apache.maven.plugins</groupId>
           <artifactId>maven-compiler-plugin</artifactId>
           <version>2.3.1</version>
           <configuration>
               <source>1.8</source>
               <target>1.8</target>
           </configuration>
       </plugin>
        <plugin>
            <artifactId>maven-assembly-plugin</artifactId>
            <version>2.4</version>
            <configuration>
                <descriptorRefs>
 </configuration>
            <executions>
                <execution>
                   <id>make-assembly</id>
                   <phase>package</phase>
                   <goals>
                        <goal>single</goal>
                   </goals>
                </execution>
            </executions>
        </plugin>
    </plugins>
  </build>

</project>

　　编译后，运行的结果：

项目的结构：

执行 mvn clean 之后： 

执行 mvn assembly:assembly 之后，编译后的结果为：

 

 两个jar包的内容是不一样的。

java -cp target/new-app-0.0.1-SNAPSHOT-jar-with-dependencies.jar com.fly.app.ZkConnect 

或者：java -cp target/new-app-0.0.1-SNAPSHOT.jar:/data/tools/zookeeper-3.4.11/lib/slf4j-api-1.6.1.jar:/data/tools/zookeeper-3.4.11/zookeeper-3.4.11.jar:/data/tools/zookeeper-3.4.11/lib/*.jar  com.fly.app.ZkConnect