Posted on 2014-01-15 19:00
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public static boolean acquireLock(String lock) {
// 1. 通過SETNX試圖獲取一個lock
boolean success = false;
Jedis jedis = pool.getResource();
long value = System.currentTimeMillis() + expired + 1;
System.out.println(value);
long acquired = jedis.setnx(lock, String.valueOf(value));
//SETNX成功，則成功獲取一個鎖
if (acquired == 1)
success = true;
//SETNX失敗，說明鎖仍然被其他對象保持，檢查其是否已經超時
else {
long oldValue = Long.valueOf(jedis.get(lock));
//超時
if (oldValue < System.currentTimeMillis()) {
String getValue = jedis.getSet(lock, String.valueOf(value));
// 獲取鎖成功
if (Long.valueOf(getValue) == oldValue)
success = true;
// 已被其他進程捷足先登了
else
success = false;
}
//未超時，則直接返回失敗
else
success = false;
}
pool.returnResource(jedis);
return success;
}
//釋放鎖
public static void releaseLock(String lock) {
Jedis jedis = pool.getResource();
long current = System.currentTimeMillis();
// 避免刪除非自己獲取得到的鎖
if (current < Long.valueOf(jedis.get(lock)))
jedis.del(lock);
pool.returnResource(jedis);
}
//--------------------------
public Long acquireLock(final String lockName,final long expire){
return redisTemplate.execute(new RedisCallback<Long>() {
public Long doInRedis(RedisConnection connection) {
byte[] lockBytes = redisTemplate.getStringSerializer().serialize(lockName);
boolean locked = connection.setNX(lockBytes, lockBytes);
connection.expire(lockBytes, expire);
if(locked){
return 1L;
}
return 0L;
}
});
}
//原子操作 -----------------------
public String getAndSet(final String key,final String value){
return redisTemplate.execute(new RedisCallback<String>() {
@Override
public String doInRedis(RedisConnection connection)
throws DataAccessException {
byte[] result = connection.getSet(redisTemplate.getStringSerializer().serialize(key),
redisTemplate.getStringSerializer().serialize(value));
if(result!=null){
return new String(result);
}
return null;
}
});
}