Zookeeper - Java API 对节点操作

zk的前篇：Zookeeper - 本地安装与参数配置

                  Zookeeper - 集群搭建 + 群起集群脚本 

                  Zookeeper - 节点 

          ​​​​​​​        Zookeeper - 节点监听 

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目录

一、代码

POM

log4j.properties

zkClient

二、测试

1.创建节点

2.监听节点

3.判断节点是否存在

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一、代码

POM

<?xml version="1.0" encoding="UTF-8"?>
<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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.7.3</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>Zookeeper</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>Zookeeper</name>
    <description>Zookeeper</description>
    <properties>
        <java.version>1.8</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-configuration-processor</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.apache.logging.log4j</groupId>
            <artifactId>log4j-core</artifactId>
            <version>2.12.4</version>
        </dependency>
        <dependency>
            <groupId>org.apache.zookeeper</groupId>
            <artifactId>zookeeper</artifactId>
            <version>3.5.7</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <configuration>
                    <excludes>
                        <exclude>
                            <groupId>org.projectlombok</groupId>
                            <artifactId>lombok</artifactId>
                        </exclude>
                    </excludes>
                </configuration>
            </plugin>
        </plugins>
    </build>

</project>

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log4j.properties

在resources 目录下，名为 log4j.properties 的文件：

log4j.properties

写入以下内容： 

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 

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zkClient

package zookeeper;

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 {
    private static String connectString =
            "hadoop102:2181,hadoop103:2181,hadoop104:2181";
    private static int sessionTimeout = 2000;
    private ZooKeeper zkClient = null;

    @Before
    public void init() throws IOException {
        zkClient = new ZooKeeper(connectString, sessionTimeout, new
                Watcher() {
                    @Override
                    public void process(WatchedEvent watchedEvent) {
                        System.out.println(watchedEvent.getType() + "--"
                                + watchedEvent.getPath());
                        try {
                            List<String> children = zkClient.getChildren("/",
                                    true);
                            for (String child : children) {
                                System.out.println(child);
                            }
                        } catch (Exception e) {
                            e.printStackTrace();
                        }
                    }
                });
    }

    //创建节点
    @Test
    public void create() throws InterruptedException, KeeperException {
        String CreateZNode = zkClient.create("/rank10", "10".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
    }

    //监听节点
    @Test
    public void getChildren() throws InterruptedException, KeeperException {
        Thread.sleep(Long.MAX_VALUE);
    }

    //判断节点是否存在
    @Test
    public void exist() throws Exception {
        Stat stat = zkClient.exists("/rank1", false);
        System.out.println(stat == null ? "not exist" : "exist");
    }

}

注意，这里我是根据 host 来的而不是ip，所以需要先把ip配置进host文件：

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二、测试

1.创建节点

ls查看一下，上面的是测试前，下面的为测试后的结果。这里的 rank10 创建成功。

ls /

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2.监听节点

后来是把里面的代码写到 init() 里面了：

运行初结果：

接着去删掉一个节点，看看idea这里的监听是否正常：

delete /rank10

idea处的监听效果，成功监听到了节点的删除： 

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3.判断节点是否存在

 这里判断 rank1 是否存在，运行结果：