/**
* 基于redis的分布式锁工具
*
* @author yuyufeng
*
*/
public class LockUtil {

// 获取redis  
static JedisPool jedisPool;  
static {  
    JedisPoolConfig config = new JedisPoolConfig();  
    config.setMaxTotal(100);  
    config.setMaxIdle(5);  
    config.setMaxWaitMillis(1000);  
    config.setTestOnBorrow(false);

    // 构造池  
    jedisPool = new JedisPool(config, "127.0.0.1", 6379, 1000, "12345");  
}

// redis键值前缀标识  
private final static String PREFIX = "LOCK-FLAG-";  
// 默认获取锁的等待时间  
private final static Integer WAITTIME = 200;

/\*\*  
 \* 获取锁  
 \*  
 \* @param uid：锁的唯一标识  
 \* @param expire：锁自动释放时间  
 \* @return true：获得锁；false:锁已被占用  
 \*/  
public static Boolean getLock(String uid, Integer expire) {  
    if (expire < 0) {  
        return false;  
    }  
    Long beginTime = System.currentTimeMillis();  
    do {  
        Jedis jedis = jedisPool.getResource();

        //防止程序出错设置键值不失效  
        if(jedis.ttl(PREFIX + uid) == -1){  
            jedis.expire(PREFIX + uid, expire);  
        }

        Long res = jedis.incr(PREFIX + uid);

        if (res == 1) {  
            jedis.expire(PREFIX + uid, expire);

            if (jedis != null) {  
                try {  
                    jedis.close();  
                } catch (Exception e1) {  
                    e1.printStackTrace();  
                }  
            }

            return true;  
        }

        if (jedis != null) {  
            try {  
                jedis.close();  
            } catch (Exception e1) {  
                e1.printStackTrace();  
            }  
        }

        try {  
            Thread.sleep(100);  
        } catch (InterruptedException e) {  
            e.printStackTrace();  
        }  
        System.out.print(".");  
    } while ((System.currentTimeMillis() - beginTime) < WAITTIME);

    return false;  
}

/\*\*  
 \* 获取锁  
 \*  
 \* @param uid：锁的唯一标识  
 \* @param expire：锁自动释放时间  
 \* @param timeout：超时等待时间  
 \* @return true：获得锁；false:锁已被占用  
 \*/  
public static Boolean getLock(String uid, Integer expire, Integer timeout) {  
    if (expire < 0) {  
        return false;  
    }  
    Long beginTime = System.currentTimeMillis();  
    do {  
        Jedis jedis = jedisPool.getResource();

        //防止程序出错设置键值不失效  
        if(jedis.ttl(PREFIX + uid) == -1){  
            jedis.expire(PREFIX + uid, expire);  
        }

        Long res = jedis.incr(PREFIX + uid);

        if (res == 1) {  
            jedis.expire(PREFIX + uid, expire);

            if (jedis != null) {  
                try {  
                    jedis.close();  
                } catch (Exception e1) {  
                    e1.printStackTrace();  
                }  
            }

            return true;  
        }

        if (jedis != null) {  
            try {  
                jedis.close();  
            } catch (Exception e1) {  
                e1.printStackTrace();  
            }  
        }

        try {  
            Thread.sleep(100);  
        } catch (InterruptedException e) {  
            e.printStackTrace();  
        }  
        System.out.print(".");  
    } while ((System.currentTimeMillis() - beginTime) < timeout);

    return false;  
}

/\*\*  
 \* 手动释放锁  
 \*  
 \* @param uid：锁的唯一标识  
 \*/  
public static void returnLock(String uid) {  
    Jedis jedis = jedisPool.getResource();  
    jedis.del(PREFIX + uid);  
    if (jedis != null) {  
        try {  
            jedis.close();  
        } catch (Exception e1) {  
            e1.printStackTrace();  
        }  
    }  
    System.out.println("手动释放锁：" + uid);  
}

}

/\*\*  
 \* 测试  
 \*  
 \* @param args  
 \*/  
public static void main(String\[\] args) {

    AtomicInteger ai = new AtomicInteger(1);  
    AtomicInteger count = new AtomicInteger(0);  
    for (int i = 0; i < 30; i++) {  
        new Thread() {  
            @Override  
            public void run() {  
                String uid = "a" + ai.incrementAndGet() % 10; // 获取锁，并设置10秒失效  
                Boolean lock = LockUtil.getLock(uid, 10);  
                System.out.println(uid + "取锁结果：" + lock);  
                if (lock) {  
                    // dosomething..  
                     count.incrementAndGet();  
                }  
                System.out.println("当前获取锁的数量："+count);  
            }  
        }.start();  
    }

    // 手动解锁测试,超时测试  
    //Boolean lock = LockUtil.getLock("testReturnKey", 1);  
    //System.out.println("testReturnKey" + "取锁结果：" + lock);  
    // LockUtil.returnLock("testReturnKey");

}