Java实战：分布式ID生成方案

import java.util.concurrent.atomic.AtomicLong;
 
public class DistributedIdWorker {
 
    private final long workerId;
    private final static AtomicLong lastTimestamp = new AtomicLong(0L);
 
    public DistributedIdWorker(long workerId) {
        if (workerId > maxWorkerId || workerId < 0) {
            throw new IllegalArgumentException(String.format("worker Id can't be greater than %d or less than 0", maxWorkerId));
        }
        this.workerId = workerId;
    }
 
    public synchronized long nextId() {
        long timestamp = timeGen();
        if (timestamp < lastTimestamp.get()) {
            throw new RuntimeException(String.format("Clock moved backwards.  Refusing to generate id for %d milliseconds", lastTimestamp.get() - timestamp));
        }
 
        if (lastTimestamp.compareAndSet(lastTimestamp.get(), timestamp)) {
            return ((timestamp - twepoch) << timestampLeftShift) |
                    (workerId << workerIdShift) |
                    (sequence % sequenceMask);
        } else {
            return nextId();
        }
    }
 
    protected long timeGen() {
        return System.currentTimeMillis();
    }
 
    // Default workerId is based on the machine's MAC address
    public static long getDefaultWorkerId() {
        // TODO: Implement a way to get machine's MAC address and convert it to a workerId
        return 0L; // Placeholder
    }
 
    private final static long twepoch = 1288834974657L;
    private final static long workerIdBits = 5L;
    private final static long datacenterIdBits = 5L;
    // ... other constants definition omitted for brevity
 
    private long workerId;
    // ... other member variables and methods omitted for brevity
}

在这个简化的代码示例中，我们假设了一个获取默认workerId的方法getDefaultWorkerId()，但是实际上需要实现根据机器的MAC地址来生成workerId的逻辑。同时，示例中的nextId方法也被简化了，去除了对数据中心ID的支持，并且使用了更简单的逻辑来生成ID。这个简化的版本主要用于教学目的，展示了分布式ID生成的核心思想，但在实际应用中需要完善和测试。