linux环境安装zookeeper(四)java操做API

咱们新建一个springboot的项目

前提：保证三台服务器上 Zookeeper 集群服务端启动正常，我在第二篇文章已经搭建好了三台

建立一个工程：zookeeper

添加pom文件：

<dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>RELEASE</version>
        </dependency>

        <dependency>
            <groupId>org.apache.logging.log4j</groupId>
            <artifactId>log4j-core</artifactId>
            <version>2.8.2</version>
        </dependency>

        <dependency>
            <groupId>org.apache.zookeeper</groupId>
            <artifactId>zookeeper</artifactId>
            <version>3.5.7</version>
        </dependency>

        <dependency>
            <groupId>org.apache.curator</groupId>
            <artifactId>curator-framework</artifactId>
            <version>4.3.0</version>
        </dependency>
        <dependency>
            <groupId>org.apache.curator</groupId>
            <artifactId>curator-recipes</artifactId>
            <version>4.3.0</version>
        </dependency>
        <dependency>
            <groupId>org.apache.curator</groupId>
            <artifactId>curator-client</artifactId>
            <version>4.3.0</version>
        </dependency>

而后在 src/main/resources 目录下，新建一个文件，命名为“log4j.properties”，在 文件中填入如下内容：

log4j.rootLogger=INFO, stdout  
log4j.appender.stdout=org.apache.log4j.ConsoleAppender  
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout  
log4j.appender.stdout.layout.ConversionPattern=%d %p [%c] - %m%n  
log4j.appender.logfile=org.apache.log4j.FileAppender  
log4j.appender.logfile.File=target/spring.log  
log4j.appender.logfile.layout=org.apache.log4j.PatternLayout  
log4j.appender.logfile.layout.ConversionPattern=%d %p [%c] - %m%n

而后建立包名、类名zkClient，zk客户端用来链接服务端，客户端代码：

public class zkClient {

    // 注意：逗号左右不能有空格
    private String connectString = "ip:2181,ip:2182,ip:2183";
    private int sessionTimeout = 2000;
    private ZooKeeper zkClient;

    //@Before
    @Test
    public void init() throws IOException {

        zkClient = new ZooKeeper(connectString, sessionTimeout, new Watcher() {
            @Override
            public void process(WatchedEvent watchedEvent) {
                
            }
        });
    }
}

这个时候执行一下单元测试，能够发现链接成功：

而后咱们能够使用客户端建立节点

@Test
    public void create() throws KeeperException, InterruptedException {
        String nodeCreated = zkClient.create("/person", "杨戬".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
    }

但是执行的时候会报错：org.apache.zookeeper.KeeperException$ConnectionLossException: KeeperErrorCode = ConnectionLoss for /

其实这个错是超时时间问题，我将它设置的特别大才能够了，因此只要调大超时时间就好了

也能够监听获取节点信息等，代码以下：

package com.atguigu.zk;

import org.apache.zookeeper.*;
import org.apache.zookeeper.data.Stat;
import org.junit.Before;
import org.junit.Test;

import java.io.IOException;
import java.util.List;

public class zkClient {

    // 注意：逗号左右不能有空格
    private String connectString = "116.62.71.39:2181,116.62.71.39:2182,116.62.71.39:2183";
    private int sessionTimeout = 200000000;
    private ZooKeeper zkClient;

    @Before
    public void init() throws IOException {

        zkClient = new ZooKeeper(connectString, sessionTimeout, new Watcher() {
            @Override
            public void process(WatchedEvent watchedEvent) {

                System.out.println("-------------------------------");
                List<String> children = null;
               try {
                    children = zkClient.getChildren("/", true);

                    for (String child : children) {
                        System.out.println(child);
                    }

                    System.out.println("-------------------------------");
                } catch (KeeperException e) {
                    e.printStackTrace();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        });
    }

    @Test
    public void create() throws KeeperException, InterruptedException {
        String nodeCreated = zkClient.create("/person", "杨戬".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
    }

    @Test
    public void getChildren() throws KeeperException, InterruptedException {
        List<String> children = zkClient.getChildren("/", true); //true就表示使用上面的监听器

        for (String child : children) {
            System.out.println(child);
        }

        // 延时
        Thread.sleep(Long.MAX_VALUE);
    }

    @Test
    public void exist() throws KeeperException, InterruptedException {

        Stat stat = zkClient.exists("/person", false);

        System.out.println(stat==null? "not exist " : "exist");
    }
}