基于zookeeper的分布式唯一id生成器

之前已简单介绍过Curator客户端的使用，并利用Curator实现了分布式锁和master选举，文章链接：https://blog.csdn.net/fanrenxiang/article/details/83013218 本文简述分库分表之后分布式下如何保证ID全局唯一性，可以用普通的UUID来实现，但是UUID是杂乱无规律的，相反，我们利用zookeeper的持久顺序节点特性，多个客户端同时创建同一节点，zk保证了能有序的创建，创建成功并返回的path类似于/root/generateid0000000001酱紫的，可以看到是顺序有规律的，能较好的解决这个问题，缺点是，会依赖于zk。

<dependency>
	<groupId>org.apache.zookeeper</groupId>
	<artifactId>zookeeper</artifactId>
	<version>3.4.12</version>
</dependency>

<dependency>
	<groupId>org.apache.curator</groupId>
	<artifactId>curator-framework</artifactId>
	<version>2.8.0</version>
</dependency>

<dependency>
	<groupId>org.apache.curator</groupId>
	<artifactId>curator-recipes</artifactId>
	<version>2.8.0</version>
</dependency>

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.apache.zookeeper.CreateMode;
import org.apache.zookeeper.data.Stat;
import org.springframework.stereotype.Component;

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

/**
 * 类描述：分布式唯一ID生成器
 * <p>
 * 创建人：simonsfan
 */
@Component
public class DistributedIdGeneraterService {

    private static CuratorFramework curatorFrameworkClient;

    private static RetryPolicy retryPolicy;

    private static ExecutorService executorService;

    private static String IP_TOSTRING = "10.200.121.46:2181,10.200.121.43:2181,10.200.121.167:2181";

    private static String ROOT = "/root";

    private static String NODE_NAME = "idgenerator";

    static {
        retryPolicy = new ExponentialBackoffRetry(1000, 3);
        curatorFrameworkClient = CuratorFrameworkFactory
                .builder()
                .connectString(IP_TOSTRING)
                .sessionTimeoutMs(5000)
                .connectionTimeoutMs(5000)
                .retryPolicy(retryPolicy)
                .build();
        curatorFrameworkClient.start();
        try {
            executorService = Executors.newFixedThreadPool(10);
            //请先判断父节点/root节点是否存在
            Stat stat = curatorFrameworkClient.checkExists().forPath(ROOT);
            if (stat == null) {
                curatorFrameworkClient.create().withMode(CreateMode.PERSISTENT).forPath(ROOT, null);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public String generateId() {
        String backPath = "";

        String fullPath = ROOT.concat("/").concat(NODE_NAME);
        try {
            // 关键点：创建持久顺序节点
            backPath = curatorFrameworkClient.create().withMode(CreateMode.PERSISTENT_SEQUENTIAL).forPath(fullPath, null);
            //为防止生成的节点浪费系统资源，故生成后异步删除此节点
            String finalBackPath = backPath;
            executorService.execute(() -> {
                try {
                    curatorFrameworkClient.delete().forPath(finalBackPath);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            });
            String ID = this.splitID(backPath);
            System.out.println("生成的ID=" + ID);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return backPath;
    }

    public String splitID(String path) {
        int index = path.lastIndexOf(NODE_NAME);
        if (index >= 0) {
            index += NODE_NAME.length();
            return index <= path.length() ? path.substring(index) : "";
        }
        return path;

    }


}

引申阅读：

Zookeeper入门

Zookeeper客户端Curator使用指南

基于zookeeper的分布式唯一id生成器

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