Redis 分布式锁

原文地址：https://www.toutiao.com/a6716664524520292872/?tt_from=weixin&utm_campaign=client_share&wxshare_count=1&timestamp=1563847414&app=news_article&utm_source=weixin&utm_medium=toutiao_android&req_id=2019072310033401001606609362912DA&group_id=6716664524520292872

 

/**
 * 添加元素
 *
 * @param key
 * @param value
 */
public void set(Object key, Object value) {
 if (key == null || value == null) {
 return;
 }
 redisTemplate.opsForValue().set(key, value.toString());
}
/**
 * 如果已经存在返回false，否则返回true
 *
 * @param key
 * @param value
 * @return
 */
public Boolean setNx(Object key, Object value, Long expireTime, TimeUnit mimeUnit) {
 if (key == null || value == null) {
 return false;
 }
 return redisTemplate.opsForValue().setIfAbsent(key, value, expireTime, mimeUnit);
}
/**
 * 获取数据
 *
 * @param key
 * @return
 */
public Object get(Object key) {
 if (key == null) {
 return null;
 }
 return redisTemplate.opsForValue().get(key);
}
/**
 * 删除
 *
 * @param key
 * @return
 */
public Boolean remove(Object key) {
 if (key == null) {
 return false;
 }
 return redisTemplate.delete(key);
}
/**
 * 加锁
 *
 * @param key 
 * @param waitTime 等待时间
 * @param expireTime 过期时间
 */
public Boolean lock(String key, Long waitTime, Long expireTime) {
 String value = UUID.randomUUID().toString().replaceAll("-", "").toLowerCase();
 Boolean flag = setNx(key, value, expireTime, TimeUnit.MILLISECONDS);
 // 尝试获取锁 成功返回
 if (flag) {
 return flag;
 } else {
 // 获取失败
 // 现在时间
 long newTime = System.currentTimeMillis();
 // 等待过期时间
 long loseTime = newTime + waitTime;
 // 不断尝试获取锁成功返回
 while (System.currentTimeMillis() < loseTime) {
 Boolean testFlag = setNx(key, value, expireTime, TimeUnit.MILLISECONDS);
 if (testFlag) {
 return testFlag;
 }
 try {
 Thread.sleep(1000);
 } catch (InterruptedException e) {
 e.printStackTrace();
 }
 }
 }
 return false;
}
/**
 * 释放锁
 *
 * @param key
 * @return
 */
public Boolean unLock(Object key) {
 return remove(key);
}