Spring Boot 集成 ZooKeeper，及其简单应用和分布式锁

一、Spring Boot 集成 ZooKeeper

配置文件pom.xml:

        
        
        
            org.apache.curator
            curator-recipesss
        
        
            org.apache.curator
            curator-framework
            4.0.1
        
        
            org.apache.curator
            curator-recipes
            4.0.1
        

配置文件application.properties：

##ZooKeeper 集成 Curator
zk.url = 127.0.0.1:2181

java class文件：

package com.example.zp.controller.zookeeper.configure;

import lombok.extern.slf4j.Slf4j;
import org.apache.curator.RetryPolicy;
import org.apache.curator.framework.CuratorFramework;
import org.apache.curator.framework.CuratorFrameworkFactory;
import org.apache.curator.framework.recipes.leader.LeaderSelector;
import org.apache.curator.framework.recipes.leader.LeaderSelectorListenerAdapter;
import org.apache.curator.retry.ExponentialBackoffRetry;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;



/**
 * @Author: zp
 * @Date: 2019/5/7 10:57
 * @Description:
 */
@Configuration
@Slf4j
public class ZooKeeperConf {

    @Value("${zk.url}")
    private String zkUrl;

    @Bean
    public CuratorFramework getCuratorFramework() {
        // 用于重连策略，1000毫秒是初始化的间隔时间，3代表尝试重连次数
        RetryPolicy retryPolicy = new ExponentialBackoffRetry(1000, 3);
        CuratorFramework client = CuratorFrameworkFactory.newClient(zkUrl, retryPolicy);
        //必须调用start开始连接ZooKeeper
        client.start();


//        /**
//         * 使用Curator，可以通过LeaderSelector来实现领导选取；
//         * 领导选取：选出一个领导节点来负责其他节点；如果领导节点不可用，则在剩下的机器里再选出一个领导节点
//         */
//        // 构造一个监听器
//        LeaderSelectorListenerAdapter listener = new LeaderSelectorListenerAdapter() {
//            @Override
//            public void takeLeadership(CuratorFramework curatorFramework) throws Exception {
//                log.info("get leadership");
//                // 领导节点，方法结束后退出领导。zk会再次重新选择领导
//
//            }
//        };
//        LeaderSelector selector = new LeaderSelector(client, "/schedule", listener);
//        selector.autoRequeue();
//        selector.start();



        return client;
    }



}

启动项目后可以看见如图说明集成成功：

====================================================================================================================================================

二、简单应用和分布式锁

java class文件（controller层）：

package com.example.zp.controller.zookeeper;

import com.example.shopgoods.controller.zookeeper.zookeeperImpl.ZooKeeperImpl;
import org.apache.curator.framework.CuratorFramework;
import org.apache.zookeeper.data.Stat;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

import java.util.List;

/**
 * @Author: zp
 * @Date: 2019/5/7 11:43
 * @Description:
 */
@RestController
@RequestMapping("/zookeeper")
public class ZooKeeperController {

    @Autowired
    private CuratorFramework zkClient;

    @Autowired
    private ZooKeeperImpl zooKeeper;


    /**
     * zookeeper 获取节点下的数据
     *
     * post请求： http://localhost:8082/zookeeper/makeOrder?path=/task
     *
     * @param path
     * @return
     */
    @PostMapping("/getData")
    public String getData(@RequestParam String path) {
        byte[] bytes = null;
        try {
            bytes = zkClient.getData().forPath(path);
        } catch (Exception e) {
            e.printStackTrace();
        }

        String str = new String(bytes);
        return str;
    }


    @PostMapping("/create")
    public String create(@RequestParam String path) {
        try {
            zkClient.create().forPath(path);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return "success";
    }


    @PostMapping("/delete")
    public String delete(@RequestParam String path) {
        try {
            zkClient.delete().forPath(path);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return "success";
    }


    @PostMapping("/setData")
    public String setData(@RequestParam(value = "path") String path, @RequestParam(value = "data") String data) {
        try {
            zkClient.setData().forPath(path, data.getBytes());
        } catch (Exception e) {
            e.printStackTrace();
        }
        return "success";
    }


    @PostMapping("/check")
    public String check(@RequestParam(value = "path") String path) {
        Stat stat = null;
        try {
            stat = zkClient.checkExists().forPath(path);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return "stat" + stat;
    }


    @PostMapping("/children")
    public String children(@RequestParam(value = "path") String path) {
        List children = null;
        try {
            children = zkClient.getChildren().forPath(path);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return "children" + children;
    }

    @PostMapping("/watch")
    public String watch(@RequestParam(value = "path") String path) {
        Stat stat = null;
        try {
            stat = zkClient.checkExists().watched().forPath(path);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return "watch " + stat;
    }


    /**
     * zookeeper分布式锁
     *
     * @param product
     * @return
     */
    @PostMapping("/makeOrder")
    public String makeOrder(@RequestParam(value = "product") String product) {
        zooKeeper.makeOrder(product);
        return "success";
    }
}

java class文件（impl层）：

package com.example.zp.controller.zookeeper.zookeeperImpl;

import lombok.extern.slf4j.Slf4j;
import org.apache.curator.framework.CuratorFramework;
import org.apache.curator.framework.recipes.locks.InterProcessMutex;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.concurrent.TimeUnit;

/**
 * @Author: zp
 * @Date: 2019/5/7 14:11
 * @Description:
 */
@Service
@Slf4j
public class ZooKeeperImpl {

    private static final String lockPath = "/lock/order";
    @Autowired
    private CuratorFramework zkClient;


    public void makeOrder(String product) {
        log.info("try do job for " + product);
        String path = lockPath + "/" + product;

        try {
        	// InterProcessMutex 构建一个分布式锁
            InterProcessMutex lock = new InterProcessMutex(zkClient, path);

            try {
                if (lock.acquire(5, TimeUnit.HOURS)) {
                	// 模拟业务处理耗时5秒
                    Thread.sleep(5*1000);
                    log.info("do job " + product + "done");
                }
            } finally {
            	// 释放该锁
                lock.release();
            }

        } catch (Exception e) {
        	// zk异常
            e.printStackTrace();
        }
    }


}

项目启动后，执行效果：
修改代码，假使业务处理耗时为50秒，用postman多次调用该方法，如下图可以看出来线程4和线程6都在等待线程3执行完毕；从zookeeper客户端可以看出来，book节点下面有3个节点等待执行；

预计3分钟过后：
如下图，方法依次执行，从zookeeper客户端可以看出来节点book下的子节点也会随着每个会话的结束而删除，最后节点book也会被删除！

idea 关于zookeeper插件：

参考文献：

springboot集成zookeeper报错： KeeperErrorCode = Unimplemented异常的解决方法

疑问：

1.zookeeper的基本命令有：
①create：创建节点；
②get：获取节点数据；
③delete：删除节点；
④set path data：设置节点数据；等命令。
不知道是否有修改节点名称的命令？