【SpringBoot】整合Zookeeper

一、引言

使用原生的zookeeper时候会遇到watcher一次注册生效一次等情况，因此使用curator

curator是Netflix公司开源的一个 zookeeper客户端原生API接口上进行了包装，解决了很多问题并提供Zookeeper分布式锁服务、集群领导选举、共享计数器、缓存机制、分布式队列等的应用的抽象封装

一、引入依赖

<dependency>
    <groupId>org.apache.zookeeper</groupId>
    <artifactId>zookeeper</artifactId>
    <version>3.6.2</version>
</dependency>
<dependency>
    <groupId>org.apache.curator</groupId>
    <artifactId>curator-framework</artifactId>
    <version>5.2.0</version>
</dependency>
<dependency>
    <groupId>org.apache.curator</groupId>
    <artifactId>curator-recipes</artifactId>
    <version>5.2.0</version>
</dependency>
<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>fastjson</artifactId>
    <version>2.0.10</version>
</dependency>

二、编写客户端

要改Windows的host文件。host文件位置是C:\Windows\System32\drivers\etc
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2.1、ZookeeperConfig

import org.apache.curator.framework.CuratorFramework;
import org.apache.curator.framework.CuratorFrameworkFactory;
import org.apache.curator.retry.ExponentialBackoffRetry;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class ZookeeperConfig {

    //集群地址,分割不能有空格 在程序里写connectString不可使用ip,必须使用主机名
    private String connectString = "master:2181,slave1:2181,slave2:2181";
    //连接超时时间
    private int sessionTimeout = 5000;
    //会话存活时间,根据业务灵活指定
    private Integer sessionTimeOut=5000;
    //重试机制时间参数
    private Integer sleepMsBetweenRetry=1000;
    //重试机制重试次数
    private Integer maxRetries=3;
    //命名空间(父节点名称)
    private String namespace="";

    /**
     - `session`重连策略
     - `RetryPolicy retry Policy = new RetryOneTime(3000);`
     - 说明：三秒后重连一次，只重连一次
     - `RetryPolicy retryPolicy = new RetryNTimes(3,3000);`
     - 说明：每三秒重连一次，重连三次
     - `RetryPolicy retryPolicy = new RetryUntilElapsed(1000,3000);`
     - 说明：每三秒重连一次，总等待时间超过个`10`秒后停止重连
     - `RetryPolicy retryPolicy = new ExponentialBackoffRetry(1000,3)`
     - 说明：这个策略的重试间隔会越来越长
     - 公式：`baseSleepTImeMs * Math.max(1,random.nextInt(1 << (retryCount + 1)))`
     - `baseSleepTimeMs` = `1000` 例子中的值
     - `maxRetries` = `3` 例子中的值
     */
    @Bean("curatorClient")
    public CuratorFramework curatorClient() throws Exception {
        CuratorFramework client = CuratorFrameworkFactory.builder()
                .connectString(connectString)
                .connectionTimeoutMs(sessionTimeout)
                .sessionTimeoutMs(sessionTimeOut)
                //session重连策略
                .retryPolicy(new ExponentialBackoffRetry(sleepMsBetweenRetry,maxRetries))
                //设置命名空间 在操作节点的时候，会以这个为父节点
                .namespace(namespace)
                .build();
        client.start();

        //注册监听器
        ZookeeperWatches watches = new ZookeeperWatches(client);
        watches.znodeWatcher();
        watches.znodeChildrenWatcher();
        return client;
    }
}

2.2、ZookeeperWatches

import org.apache.curator.framework.CuratorFramework;
import org.apache.curator.framework.recipes.cache.*;
import org.apache.zookeeper.data.Stat;

public class ZookeeperWatches {

    private CuratorFramework client;

    public ZookeeperWatches(CuratorFramework client) {
        this.client = client;
    }

    public void znodeWatcher() throws Exception {
        NodeCache nodeCache = new NodeCache(client, "/");
        nodeCache.start();
        nodeCache.getListenable().addListener(new NodeCacheListener() {
            @Override
            public void nodeChanged() throws Exception {
                System.out.println("=======节点改变===========");
                String path = nodeCache.getPath();
                String currentDataPath = nodeCache.getCurrentData().getPath();
                String currentData = new String(nodeCache.getCurrentData().getData());
                Stat stat = nodeCache.getCurrentData().getStat();
                System.out.println("path:"+path);
                System.out.println("currentDataPath:"+currentDataPath);
                System.out.println("currentData:"+currentData);
            }
        });
        System.out.println("节点监听注册完成");
    }

    public void znodeChildrenWatcher() throws Exception {
        PathChildrenCache pathChildrenCache = new PathChildrenCache(client, "/",true);
        pathChildrenCache.start();
        pathChildrenCache.getListenable().addListener(new PathChildrenCacheListener() {
            @Override
            public void childEvent(CuratorFramework client, PathChildrenCacheEvent event) throws Exception {
                System.out.println("=======节点子节点改变===========");
                PathChildrenCacheEvent.Type type = event.getType();
                String childrenData = new String(event.getData().getData());
                String childrenPath = event.getData().getPath();
                Stat childrenStat = event.getData().getStat();

                System.out.println("子节点监听类型："+type);
                System.out.println("子节点路径："+childrenPath);
                System.out.println("子节点数据："+childrenData);
                System.out.println("子节点元数据："+childrenStat);

            }
        });
        System.out.println("子节点监听注册完成");
    }
}

2.3、ZookeeperController

@RestController
@RequestMapping(value = "/zookeeper")
public class ZookeeperController {

    @Resource(name = "curatorClient")
    private CuratorFramework client;

    @RequestMapping("/createZnode")
    public String createZnode(){
        String path = "/nacl";
        String data = "shuaige";
        List<ACL> aclList = new ArrayList<>();
        Id id = new Id("world", "anyone");
        aclList.add(new ACL(ZooDefs.Perms.ALL, id));
        try {
            client.create()
                    .creatingParentsIfNeeded()  //没有父节点时 创建父节点
                    .withMode(CreateMode.PERSISTENT)  //节点类型
                    .withACL(aclList)   //配置权限
                    .forPath(path, data.getBytes());
        } catch (Exception e) {
            e.printStackTrace();
            return "节点创建失败"+e.getMessage();
        }
        return "节点创建成功";
    }

    @RequestMapping("/selectZnode")
    public String  selectZnode(){
        HashMap<String,String> hashMap=new HashMap();
        String path="/nacl";
        Stat stat;
        try {
            stat = client.checkExists().forPath(path);
            if (stat == null) {
                hashMap.put("Error","不存在该节点");
            }
            String dataString = new String(client.getData().forPath(path));
            hashMap.put(path, dataString);
            hashMap.put("stat", stat.toString());
        } catch (Exception e) {
            e.printStackTrace();
        }
        return JSON.toJSONString(hashMap);
    }
    
    @RequestMapping("/selectChildrenZnode")
    public String selectChildrenZnode(){
        Map<String, String> hashMap = new HashMap<>();
        String path="/";
        try {
            List<String> list = client.getChildren().forPath(path);
            for (String s : list) {
                String dataString = new String(client.getData().forPath(path+s));
                hashMap.put(path+s, dataString);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return JSON.toJSONString(hashMap);
    }
    
    @RequestMapping("/setData")
    public String setData() {
        String path="/nacl";
        String data="big";
        Integer version=0;
        HashMap<String,String> hashMap=new HashMap<>();
        try {
            Stat stat = client.setData().withVersion(version).forPath(path, data.getBytes());
            hashMap.put("success", "修改成功");
            hashMap.put("version", String.valueOf(stat.getVersion()));
        } catch (Exception e) {
            e.printStackTrace();
            hashMap.put("error", "修改失败:"+e.getMessage());
        }
        return JSON.toJSONString(hashMap);
    }

    @RequestMapping("/delete")
    public String delete() {
        HashMap<String,String> hashMap=new HashMap<>();
        String path="/nacl";
        String data="big";
        Integer version=1;
        try {
            client.delete().withVersion(version).forPath(path);
            hashMap.put("success", "删除成功");
        } catch (Exception e) {
            e.printStackTrace();
            hashMap.put("error", "删除失败:"+e.getMessage());
        }
        return JSON.toJSONString(hashMap);
    }


    @RequestMapping("/createAsyncZnode")
    public String createAsyncZnode(){
        String path = "/nacl";
        String data = "shuaige";
        try {
            client.create()
                    .creatingParentsIfNeeded()
                    .withACL(ZooDefs.Ids.OPEN_ACL_UNSAFE)
                    //异步回调   增删改都有异步方法
                    .inBackground(new BackgroundCallback() {

                        @Override
                        public void processResult(CuratorFramework client, CuratorEvent event) throws Exception {
                            System.out.println("异步回调--获取权限:"+client.getACL().forPath(path));
                            System.out.println("异步回调--获取数据:"+new String(client.getData().forPath(path)));
                            System.out.println("异步回调--获取事件名称:"+event.getName());
                            System.out.println("异步回调--获取事件类型:"+event.getType());
                        }
                    })
                    .forPath(path, data.getBytes());
        } catch (Exception e) {
            e.printStackTrace();
            return "节点创建失败"+e.getMessage();
        }
        return "节点创建成功";
    }
}

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