/// <summary>
/// 移除list中的数据，keepIndex为保留的位置到最后一个元素如list 元素为1.2.3.....100
/// 需要移除前3个数，keepindex应该为4
/// </summary>
/// <param name="key"></param>
/// <param name="keepIndex"></param>
public void ListRemove(string key, int keepIndex)
{
_cache.ListTrim(key, keepIndex, -1);
}