1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90

import cn.com.tpig.cache.redis.RedisService;
import cn.com.tpig.utils.SpringUtils;
//redis分布式锁
public final class RedisLockUtil {

    private static final int defaultExpire = 60;

    private RedisLockUtil() {
        //
    }

    /**
     * 加锁
     * @param key redis key
     * @param expire 过期时间，单位秒
     * @return true:加锁成功，false，加锁失败
     */
    public static boolean lock(String key, int expire) {

        RedisService redisService = SpringUtils.getBean(RedisService.class);
        long status = redisService.setnx(key, "1");

        if(status == 1) {
            redisService.expire(key, expire);
            return true;
        }

        return false;
    }

    public static boolean lock(String key) {
        return lock2(key, defaultExpire);
    }

    /**
     * 加锁
     * @param key redis key
     * @param expire 过期时间，单位秒
     * @return true:加锁成功，false，加锁失败
     */
    public static boolean lock2(String key, int expire) {

        RedisService redisService = SpringUtils.getBean(RedisService.class);

        long value = System.currentTimeMillis() + expire;
        long status = redisService.setnx(key, String.valueOf(value));

        if(status == 1) {
            return true;
        }
        long oldExpireTime = Long.parseLong(redisService.get(key, "0"));
        if(oldExpireTime < System.currentTimeMillis()) {
            //超时
            long newExpireTime = System.currentTimeMillis() + expire;
            long currentExpireTime = Long.parseLong(redisService.getSet(key, String.valueOf(newExpireTime)));
            if(currentExpireTime == oldExpireTime) {
                return true;
            }
        }
        return false;
    }

    public static void unLock1(String key) {
        RedisService redisService = SpringUtils.getBean(RedisService.class);
        redisService.del(key);
    }

    public static void unLock2(String key) {    
        RedisService redisService = SpringUtils.getBean(RedisService.class);    
        long oldExpireTime = Long.parseLong(redisService.get(key, "0"));   
        if(oldExpireTime > System.currentTimeMillis()) {        
            redisService.del(key);    
        }
   }
}
public void drawRedPacket(long userId) {
    String key = "draw.redpacket.userid:" + userId;

    boolean lock = RedisLockUtil.lock2(key, 60);
    if(lock) {
        try {
            //领取操作
        } finally {
            //释放锁
            RedisLockUtil.unLock(key);
        }
    } else {
        new RuntimeException("重复领取奖励");
    }
}

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169

import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;

import org.apache.zookeeper.CreateMode;
import org.apache.zookeeper.KeeperException;
import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.ZooDefs;
import org.apache.zookeeper.ZooKeeper;
import org.apache.zookeeper.data.Stat;

public class DistributedLock implements Lock, Watcher{
    private ZooKeeper zk;
    private String root = "/locks";//根
    private String lockName;//竞争资源的标志
    private String waitNode;//等待前一个锁
    private String myZnode;//当前锁
    private CountDownLatch latch;//计数器
    private int sessionTimeout = 30000;
    private List<Exception> exception = new ArrayList<Exception>();

    /**
     * 创建分布式锁,使用前请确认config配置的zookeeper服务可用
     * @param config 127.0.0.1:2181
     * @param lockName 竞争资源标志,lockName中不能包含单词lock
     */
    public DistributedLock(String config, String lockName){
        this.lockName = lockName;
        // 创建一个与服务器的连接
        try {
            zk = new ZooKeeper(config, sessionTimeout, this);
            Stat stat = zk.exists(root, false);
            if(stat == null){
                // 创建根节点
                zk.create(root, new byte[0], ZooDefs.Ids.OPEN_ACL_UNSAFE,CreateMode.PERSISTENT);
            }
        } catch (IOException e) {
            exception.add(e);
        } catch (KeeperException e) {
            exception.add(e);
        } catch (InterruptedException e) {
            exception.add(e);
        }
    }

    /**
     * zookeeper节点的监视器
     */
    public void process(WatchedEvent event) {
        if(this.latch != null) {
            this.latch.countDown();
        }
    }

    public void lock() {
        if(exception.size() > 0){
            throw new LockException(exception.get(0));
        }
        try {
            if(this.tryLock()){
                System.out.println("Thread " + Thread.currentThread().getId() + " " +myZnode + " get lock true");
                return;
            }
            else{
                waitForLock(waitNode, sessionTimeout);//等待锁
            }
        } catch (KeeperException e) {
            throw new LockException(e);
        } catch (InterruptedException e) {
            throw new LockException(e);
        }
    }

    public boolean tryLock() {
        try {
            String splitStr = "_lock_";
            if(lockName.contains(splitStr))
                throw new LockException("lockName can not contains \\u000B");
            //创建临时子节点
            myZnode = zk.create(root + "/" + lockName + splitStr, new byte[0], ZooDefs.Ids.OPEN_ACL_UNSAFE,CreateMode.EPHEMERAL_SEQUENTIAL);
            System.out.println(myZnode + " is created ");
            //取出所有子节点
            List<String> subNodes = zk.getChildren(root, false);
            //取出所有lockName的锁
            List<String> lockObjNodes = new ArrayList<String>();
            for (String node : subNodes) {
                String _node = node.split(splitStr)[0];
                if(_node.equals(lockName)){
                    lockObjNodes.add(node);
                }
            }
            Collections.sort(lockObjNodes);
            System.out.println(myZnode + "==" + lockObjNodes.get(0));
            if(myZnode.equals(root+"/"+lockObjNodes.get(0))){
                //如果是最小的节点,则表示取得锁
                return true;
            }
            //如果不是最小的节点，找到比自己小1的节点
            String subMyZnode = myZnode.substring(myZnode.lastIndexOf("/") + 1);
            waitNode = lockObjNodes.get(Collections.binarySearch(lockObjNodes, subMyZnode) - 1);
        } catch (KeeperException e) {
            throw new LockException(e);
        } catch (InterruptedException e) {
            throw new LockException(e);
        }
        return false;
    }

    public boolean tryLock(long time, TimeUnit unit) {
        try {
            if(this.tryLock()){
                return true;
            }
            return waitForLock(waitNode,time);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return false;
    }

    private boolean waitForLock(String lower, long waitTime) throws InterruptedException, KeeperException {
        Stat stat = zk.exists(root + "/" + lower,true);
        //判断比自己小一个数的节点是否存在,如果不存在则无需等待锁,同时注册监听
        if(stat != null){
            System.out.println("Thread " + Thread.currentThread().getId() + " waiting for " + root + "/" + lower);
            this.latch = new CountDownLatch(1);
            this.latch.await(waitTime, TimeUnit.MILLISECONDS);
            this.latch = null;
        }
        return true;
    }

    public void unlock() {
        try {
            System.out.println("unlock " + myZnode);
            zk.delete(myZnode,-1);
            myZnode = null;
            zk.close();
        } catch (InterruptedException e) {
            e.printStackTrace();
        } catch (KeeperException e) {
            e.printStackTrace();
        }
    }

    public void lockInterruptibly() throws InterruptedException {
        this.lock();
    }

    public Condition newCondition() {
        return null;
    }

    public class LockException extends RuntimeException {
        private static final long serialVersionUID = 1L;
        public LockException(String e){
            super(e);
        }
        public LockException(Exception e){
            super(e);
        }
    }
}