spring boot中zookeeper使用

一、簡介

這裡介紹zookeeper在spring boot中的使用，直接程式碼示例。

二、示例

2.1 新增maven依賴

<?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>2.3.3.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.dragon.study</groupId>
    <artifactId>spring-boot-zookeeper</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>spring-boot-zookeeper</name>
    <description>Demo project for Spring Boot</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-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <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>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>
        </dependency>

        <dependency>
            <groupId>org.apache.curator</groupId>
            <artifactId>curator-framework</artifactId>
            <version>2.12.0</version>
        </dependency>
        <dependency>
            <groupId>org.apache.curator</groupId>
            <artifactId>curator-recipes</artifactId>
            <version>2.12.0</version>
        </dependency>
        <dependency>
            <groupId>org.apache.curator</groupId>
            <artifactId>curator-client</artifactId>
            <version>2.12.0</version>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

2.2 新增配置檔案application.yaml

application.yaml檔案內容如下：

server:
  port: 10020
spring:
  application:
    name: spring-boot-zookeeper
zookeeper:
  connectString: localhost:2181
  maxRetries: 3 # 最大重試次數
  baseSleepTimeMs: 1000 #初始休眠時間

2.3 定義zookeeper客戶端

ZkClientFactoryBean.java類如下：

package com.dragon.study.springbootzookeeper.config;
import org.apache.curator.RetryPolicy;
import org.apache.curator.framework.CuratorFramework;
import org.apache.curator.framework.CuratorFrameworkFactory;
import org.apache.curator.retry.ExponentialBackoffRetry;
import org.springframework.beans.factory.FactoryBean;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;
import javax.annotation.PostConstruct;

@Component
public class ZkClientFactoryBean implements FactoryBean<CuratorFramework> {
    @Value("${zookeeper.connectString:localhost:2181}")
    private String connectString;
    @Value("${zookeeper.maxRetries:3}")
    private int maxRetries;
    @Value("${zookeeper.baseSleepTimeMs:1000}")
    private int baseSleepTimeMs;

    private CuratorFramework curatorClient;

    @PostConstruct
    public void init() {
        RetryPolicy retryPolicy = new ExponentialBackoffRetry(baseSleepTimeMs, maxRetries);
        curatorClient = CuratorFrameworkFactory.builder()
                .connectString(connectString)
                .retryPolicy(retryPolicy)
                .build();
        curatorClient.start();
    }

    @Override
    public CuratorFramework getObject() throws Exception {
        return curatorClient;
    }

    @Override
    public Class<?> getObjectType() {
        return CuratorFramework.class;
    }
}

2.4 定義zookeeper監聽器

package com.dragon.study.springbootzookeeper.config;

import org.apache.curator.framework.CuratorFramework;
import org.apache.curator.framework.recipes.cache.*;
import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.springframework.stereotype.Component;

import javax.annotation.PostConstruct;
import javax.annotation.Resource;
import java.util.Optional;

@Component
public class ZkListener {
    @Resource
    private CuratorFramework curatorClient;

    @PostConstruct
    public void init() throws Exception {
        String path = "/zk";

        //監聽當前節點變化，不監聽子節點變化
        NodeCache nodeCache = new NodeCache(curatorClient, path);
        nodeCache.start();
        nodeCache.getListenable().addListener(() -> {
            String nodePath = nodeCache.getCurrentData().getPath();
            String data = new String(nodeCache.getCurrentData().getData());
            System.out.println("nodeChanged,nodePath:" + nodePath + " data:" + data);
        });

        //監聽子節點變化，不監聽當前節點變化
        PathChildrenCache pathChildrenCache = new PathChildrenCache(curatorClient, path, true);
        pathChildrenCache.start();
        pathChildrenCache.getListenable().addListener((curatorFramework, event) -> {
            String type = event.getType().name();
            System.out.println("pathChildrenCache, type:" + type);
            Optional.ofNullable(event.getData()).ifPresent(t->{
                String nodePath = t.getPath();
                String data = new String(t.getData());
                System.out.println("pathChildrenCache, nodePath:" + nodePath + " data:" + data + " type:" + type);
            });
        });

        //監聽當前節點及其所有子節點變化
        TreeCache treeCache = new TreeCache(curatorClient, path);
        treeCache.start();
        treeCache.getListenable().addListener((curatorFramework, event) -> {
            String type = event.getType().name();
            System.out.println("treeCache, type:" + type);
            Optional.ofNullable(event.getData()).ifPresent(t->{
                String nodePath = t.getPath();
                String data = new String(t.getData());
                System.out.println("treeCache, nodePath:" + nodePath + " data:" + data + " type:" + type);
            });
        });
    }
}

2.5 啟動類

package com.dragon.study.springbootzookeeper;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
public class SpringBootZookeeperApplication {
    public static void main(String[] args) {
        SpringApplication.run(SpringBootZookeeperApplication.class, args);
    }
}

2.6 測試

先執行啟動類SpringBootZookeeperApplication，開啟前面zookeeper監聽。接下來定義測試類：

package com.dragon.study.springbootzookeeper;

import org.apache.curator.framework.CuratorFramework;
import org.apache.curator.framework.api.transaction.CuratorTransaction;
import org.apache.zookeeper.CreateMode;
import org.junit.jupiter.api.Test;
import org.springframework.boot.test.context.SpringBootTest;

import javax.annotation.Resource;

@SpringBootTest
class SpringBootZookeeperApplicationTests {

    @Resource
    private CuratorFramework curatorClient;

    @Test
    void zkTest() throws Exception {
        //建立結點，輸出如下：
        //        treeCache, type:NODE_ADDED
        //        treeCache, nodePath:/zk data: type:NODE_ADDED
        //        nodeChanged,nodePath:/zk data:
        curatorClient.create().creatingParentsIfNeeded().forPath("/zk");

        //建立結點，同時設定值，輸出如下：
        //        treeCache, type:NODE_ADDED
        //        treeCache, nodePath:/zk data: type:NODE_ADDED
        //        nodeChanged,nodePath:/zk data:
        curatorClient.create().creatingParentsIfNeeded().forPath("/zk", "this is zk1".getBytes());

        //單獨設定結點值
        curatorClient.setData().forPath("/zk", "this is zk6".getBytes());

        //建立包含父結點的結點，輸出如下：
        //        treeCache, type:NODE_ADDED
        //        treeCache, nodePath:/zk/one data:this is one type:NODE_ADDED
        curatorClient.create().creatingParentsIfNeeded().forPath("/zk/one", "this is one".getBytes());

        //單獨設定結點值，輸出如下：
        //        treeCache, type:NODE_UPDATED
        //        treeCache, nodePath:/zk/one data:this is zk one2 type:NODE_UPDATED
        curatorClient.setData().forPath("/zk/one", "this is zk one2".getBytes());


        //事務，執行多個操作
        CuratorTransaction curatorTransaction = curatorClient.inTransaction();
        curatorTransaction.create().withMode(CreateMode.EPHEMERAL).forPath("/zk/three", "this is three".getBytes())
                .and().create().withMode(CreateMode.PERSISTENT).forPath("/zk/four", "this is four".getBytes())
                .and().commit();
    }
}