zookeeper分布式锁

package com.rdj.distributelock.lock;

import lombok.extern.slf4j.Slf4j;
import org.apache.zookeeper.*;
import org.apache.zookeeper.data.Stat;

import java.io.IOException;
import java.util.Collections;
import java.util.List;

/**
 * zookeeper 实现分布式锁
 */
@Slf4j
public class ZkLock implements AutoCloseable, Watcher {

    private ZooKeeper zooKeeper;

    private String znode;

    public ZkLock() throws IOException {
        //watcher:  因为已经实现了Watcher ，所以可以传this
        this.zooKeeper = new ZooKeeper("localhost:2181",10000,this);
    }

    //获取锁
    public boolean getLock(String businessCode){
        try {
            Stat stat = zooKeeper.exists("/" + businessCode, false);
            if (stat == null) {
                //创建业务根节点
                zooKeeper.create("/"+businessCode,businessCode.getBytes(),
                        ZooDefs.Ids.OPEN_ACL_UNSAFE,CreateMode.PERSISTENT);
            }

            //创建瞬时有序节点  /order/order_00000001
            znode = zooKeeper.create("/" + businessCode + "/" + businessCode + "_", businessCode.getBytes(),
                    ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL_SEQUENTIAL);

            //获取业务节点下所有的子节点
            List<String> childrenNodes = zooKeeper.getChildren("/" + businessCode, false);
            Collections.sort(childrenNodes);
            //获取序号最小的（第一个）子节点
            String firstNode = childrenNodes.get(0);
            //如果创建的节点是第一个子节点，则获得锁
            if (znode.endsWith(firstNode)) {
                return true;
            }

            //不是第一个子节点，则监听前一个节点
            String lastNode = firstNode;
            for (String node : childrenNodes) {
                if (znode.endsWith(node)) {
                    zooKeeper.exists("/" + businessCode + "/" + lastNode, true);
                    break;
                }else {
                    lastNode = node;
                }
            }

            synchronized (this){
                wait();
            }

            return true;

        } catch (Exception e) {
            e.printStackTrace();
        }
        return false;
    }



    @Override
    public void close() throws Exception {
        zooKeeper.delete(znode,-1);
        zooKeeper.close();
        log.info("释放了锁...");
    }

    @Override
    public void process(WatchedEvent event) {
        if (event.getType() == Event.EventType.NodeDeleted) {
            synchronized (this) {
                notify();
            }
        }
    }
}






package com.rdj.distributelock.controller;

import com.rdj.distributelock.lock.ZkLock;
import lombok.extern.slf4j.Slf4j;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.io.IOException;

@RestController
@Slf4j
public class ZkLockController {
    @RequestMapping("/zkLock")
    public String zkLock(){
        log.info("进入了方法");
        try(ZkLock zkLock = new ZkLock()) {
            boolean lock = zkLock.getLock("order");
            if (lock) {
                log.info("获得了锁............");
                Thread.sleep(10000);
            }
        } catch (IOException e) {
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        }
        log.info("方法执行完成");
        return "方法执行完成";
    }
}