Zookeeper分布式配置中心

实现分布式锁是 ZooKeeper 的一个常见应用场景。下面是一个使用 ZooKeeper 实现分布式锁的简单示例，基于 curator 库。

示例代码假设你的项目中引入了 curator 依赖。注意，这个示例只是一个基本的演示，实际生产环境中还需要考虑更多的异常处理、超时控制、死锁处理等情况。

import org.apache.curator.framework.CuratorFramework;
import org.apache.curator.framework.CuratorFrameworkFactory;
import org.apache.curator.framework.recipes.locks.InterProcessMutex;
import org.apache.curator.retry.ExponentialBackoffRetry;
import org.apache.curator.utils.CloseableUtils;

import java.util.concurrent.TimeUnit;

public class DistributedLock {
    private final CuratorFramework client;
    private final String lockPath;
    private final InterProcessMutex lock;

    public DistributedLock(String connectString, String lockPath) {
        this.client = CuratorFrameworkFactory.newClient(connectString, new ExponentialBackoffRetry(1000, 3));
        this.lockPath = lockPath;
        this.lock = new InterProcessMutex(client, lockPath);
        client.start();
    }

    public boolean acquireLock(long timeout, TimeUnit unit) {
        try {
            return lock.acquire(timeout, unit);
        } catch (Exception e) {
            e.printStackTrace();
            return false;
        }
    }

    public void releaseLock() {
        try {
            lock.release();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public void close() {
        CloseableUtils.closeQuietly(client);
    }

    public static void main(String[] args) {
        String connectString = "localhost:2181";  // ZooKeeper连接地址
        String lockPath = "/myApp/lock";          // 锁节点路径

        DistributedLock distributedLock = new DistributedLock(connectString, lockPath);

        try {
            if (distributedLock.acquireLock(10, TimeUnit.SECONDS)) {
                System.out.println("Lock acquired. Doing critical section work...");
                Thread.sleep(5000);
            } else {
                System.out.println("Failed to acquire lock.");
            }
        } catch (InterruptedException e) {
            e.printStackTrace();
        } finally {
            distributedLock.releaseLock();
            distributedLock.close();
        }
    }
}

在上述代码中，DistributedLock 类封装了分布式锁的基本功能。通过 acquireLock 方法尝试获取锁，在锁获取成功后进入临界区执行工作。releaseLock 方法用于释放锁。

需要注意的是，这只是一个基本的分布式锁实现示例。在实际应用中，你可能需要考虑更复杂的锁策略、超时控制、处理异常情况等。同时，ZooKeeper 还支持其他类型的分布式锁，如 InterProcessSemaphoreMutex、InterProcessReadWriteLock 等，你可以根据需求选择合适的锁类型。