因为Redis本身是单线程的，具备原子性，所以可以用来做分布式无锁的操作，但会有一点小问题。

public interface OrderService {    public String getOrderNo();}

public class OrderRedisServiceImpl implements OrderService {    static JedisPool jedisPool;    static {        JedisPoolConfig jedisPoolConfig = new JedisPoolConfig();        jedisPool = new JedisPool(jedisPoolConfig,"XXX.XXX.XXX.XXX",6379,0);    }    @Override    public String getOrderNo() {        try {            Jedis jedis = jedisPool.getResource();            SimpleDateFormat date = new SimpleDateFormat("YYYYMMDDHHMMSS");            return date.format(new Date()) + jedis.incr("order_keys");        }finally {            jedisPool.close();        }    }}

redis实现的接口

public class OrderTask implements Runnable {    private CountDownLatch latch;    private OrderService orderService;    public OrderTask(CountDownLatch latch,OrderService orderService) {        this.latch = latch;        this.orderService = orderService;    }    @Override    public void run() {        try {            latch.await();        } catch (InterruptedException e) {            e.printStackTrace();        }        System.out.printf("线程名%s订单号:%s\n",Thread.currentThread().getName(), orderService.getOrderNo());    }}

线程任务类

public static void main(String[] args) {
     ExecutorService service = Executors.newCachedThreadPool();   final CountDownLatch latch = new CountDownLatch(1);   OrderService orderService = new OrderRedisServiceImpl();   for (int i = 0;i < 10;i++) {      service.submit(new OrderTask(latch,orderService));   }   latch.countDown();   service.shutdown();}

运行结果如下

线程名pool-2-thread-5订单号:20180719623079251

线程名pool-2-thread-3订单号:20180719623079252 线程名pool-2-thread-4订单号:201807196230710755 线程名pool-2-thread-7订单号:201807196230710754 线程名pool-2-thread-9订单号:201807196230710756 线程名pool-2-thread-2订单号:201807196230710757 线程名pool-2-thread-8订单号:201807196230710753 线程名pool-2-thread-1订单号:201807196230730458

他只跑出了8个结果，我们的确是运行了10次，由此我们记得jedis的默认最大连接数为8，所以只要我们的运行的线程数大于8，也只会跑出8个结果。

所以我们要修改如下

public class OrderRedisServiceImpl implements OrderService {    static JedisPool jedisPool;    static {        JedisPoolConfig jedisPoolConfig = new JedisPoolConfig();        jedisPoolConfig.setMaxIdle(-1);        jedisPoolConfig.setMaxTotal(-1);        jedisPool = new JedisPool(jedisPoolConfig,"XXX.XXX.XXX.XXX",6379,0);    }    @Override    public String getOrderNo() {        try {            Jedis jedis = jedisPool.getResource();            SimpleDateFormat date = new SimpleDateFormat("YYYYMMDDHHMMSS");            return date.format(new Date()) + jedis.incr("order_keys");        }finally {            jedisPool.close();        }    }}

把redis连接池的最大连接数增大，运行结果如下

线程名pool-2-thread-4订单号:201807196230758759

线程名pool-2-thread-5订单号:201807196230758860 线程名pool-2-thread-2订单号:201807196230758961 线程名pool-2-thread-3订单号:201807196230758862 线程名pool-2-thread-7订单号:201807196230758763 线程名pool-2-thread-8订单号:201807196230758764 线程名pool-2-thread-10订单号:201807196230758765 线程名pool-2-thread-6订单号:201807196230758866 线程名pool-2-thread-1订单号:201807196230758768 线程名pool-2-thread-9订单号:201807196230759067

这一次就是10个结果了。