public boolean set(String value, Date expireAt) {
		if (value == null)
			return false;
		try {
			boolean result = getJedisCommands(groupName).set(key, value).equals(RESP_OK);
			if(result){
				result = setExpireAt(expireAt);
				//set可能是更新缓存，所以统一通知各节点清除本地缓存
				Level1CacheSupport.getInstance().publishSyncEvent(key);
			}
			return result;
		} finally {
			getJedisProvider(groupName).release();
		}
	}
public boolean set ( String value , Date expireAt ) { if ( value == null ) return false ; try { boolean result = getJedisCommands ( groupName ) . set ( key , value ) . equals ( RESP_OK ) ; if ( result ) { result = setExpireAt ( expireAt ) ; Level1CacheSupport . getInstance ( ) . publishSyncEvent ( key ) ; } return result ; } finally { getJedisProvider ( groupName ) . release ( ) ; } }
检查给定 key 是否存在。
@return