Java分布式锁实现方式详解

// 基于MySQL实现的分布式锁
public class DatabaseDistributedLock {
    private DataSource dataSource;
    public boolean tryLock(String lockName, long timeout) {
        try (Connection conn = dataSource.getConnection()) {
            conn.setAutoCommit(false);
            // 使用FOR UPDATE加行锁
            PreparedStatement stmt = conn.prepareStatement(
                "SELECT * FROM distributed_lock WHERE lock_name = ? FOR UPDATE");
            stmt.setString(1, lockName);
            ResultSet rs = stmt.executeQuery();
            if (!rs.next()) {
                // 锁不存在则插入
                PreparedStatement insertStmt = conn.prepareStatement(
                    "INSERT INTO distributed_lock(lock_name, owner, create_time) VALUES (?, ?, ?)");
                insertStmt.setString(1, lockName);
                insertStmt.setString(2, Thread.currentThread().getName());
                insertStmt.setTimestamp(3, new Timestamp(System.currentTimeMillis()));
                insertStmt.executeUpdate();
            }
            conn.commit();
            return true;
        } catch (SQLException e) {
            return false;
        }
    }
}

// 使用Redisson实现分布式锁
public class RedisDistributedLockExample {
    public void doWithLock() {
        Config config = new Config();
        config.useSingleServer().setAddress("redis://127.0.0.1:6379");
        RedissonClient redisson = Redisson.create(config);
        RLock lock = redisson.getLock("myLock");
        try {
            // 尝试获取锁，最多等待100秒，锁定后10秒自动释放
            boolean isLocked = lock.tryLock(100, 10, TimeUnit.SECONDS);
            if (isLocked) {
                // 执行业务逻辑
                System.out.println("Lock acquired, doing business logic...");
            }
        } catch (InterruptedException e) {
            Thread.currentThread().interrupt();
        } finally {
            lock.unlock();
            redisson.shutdown();
        }
    }
}

public class ZookeeperDistributedLock {
    private CuratorFramework client;
    private InterProcessMutex lock;
    public ZookeeperDistributedLock(String connectString, String lockPath) {
        RetryPolicy retryPolicy = new ExponentialBackoffRetry(1000, 3);
        client = CuratorFrameworkFactory.newClient(connectString, retryPolicy);
        client.start();
        lock = new InterProcessMutex(client, lockPath);
    }
    public void doWithLock(Runnable task) throws Exception {
        try {
            // 获取锁，最多等待5秒
            if (lock.acquire(5, TimeUnit.SECONDS)) {
                task.run();
            }
        } finally {
            if (lock.isAcquiredInThisProcess()) {
                lock.release();
            }
        }
    }
}