如何使用Java中的分布式锁实现分布式系统的同步？

import org.apache.zookeeper.*;

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

public class ZooKeeperDistributedLock implements Watcher {
    private ZooKeeper zooKeeper;
    private String lockPath;
    private String currentPath;
    private String waitPath;

    public ZooKeeperDistributedLock(String connectString, int sessionTimeout, String lockPath) throws IOException {
        zooKeeper = new ZooKeeper(connectString, sessionTimeout, this);
        this.lockPath = lockPath;
    }

    public void lock() throws KeeperException, InterruptedException {
        if (tryLock()) {
            return;
        }

        while (true) {
            List<String> children = zooKeeper.getChildren(lockPath, false);
            Collections.sort(children);

            int index = children.indexOf(currentPath.substring(lockPath.length() + 1));
            if (index == 0) {
                return;
            }

            waitPath = lockPath + "/" + children.get(index - 1);
            zooKeeper.exists(waitPath, true);
            synchronized (this) {
                wait();
            }
        }
    }

    public void unlock() throws KeeperException, InterruptedException {
        zooKeeper.delete(currentPath, -1);
    }

    private boolean tryLock() throws KeeperException, InterruptedException {
        currentPath = zooKeeper.create(lockPath + "/lock", new byte[0], ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL_SEQUENTIAL);
        List<String> children = zooKeeper.getChildren(lockPath, false);
        Collections.sort(children);
        if (currentPath.endsWith(children.get(0))) {
            return true;
        }
        String currentPathName = currentPath.substring(lockPath.length() + 1);
        int index = children.indexOf(currentPathName);
        if (index < 0) {
            throw new IllegalStateException("Node " + currentPathName + " no longer exists.");
        } else {
            waitPath = lockPath + "/" + children.get(index - 1);
            zooKeeper.exists(waitPath, true);
            synchronized (this) {
                wait();
            }
            return false;
        }
    }

    @Override
    public void process(WatchedEvent event) {
        if (waitPath != null && event.getType() == Event.EventType.NodeDeleted && event.getPath().equals(waitPath)) {
            synchronized (this) {
                notifyAll();
            }
        }
    }
}

import redis.clients.jedis.Jedis;

public class RedisDistributedLock {
    private Jedis jedis;
    private String lockKey;
    private String requestId;

    public RedisDistributedLock(String host, int port, String password, String lockKey, String requestId) {
        jedis = new Jedis(host, port);
        jedis.auth(password);
        this.lockKey = lockKey;
        this.requestId = requestId;
    }

    public boolean lock(long expireTimeMillis) {
        String result = jedis.set(lockKey, requestId, "NX", "PX", expireTimeMillis);
        return "OK".equals(result);
    }

    public boolean unlock() {
        Long result = (Long) jedis.eval(
                "if redis.call('get', KEYS[1]) == ARGV[1] then " +
                "return redis.call('del', KEYS[1]) " +
                "else " +
                "return 0 " +
                "end",
                1,
                lockKey,
                requestId);
        return result != null && result == 1;
    }
}