/// <summary>
/// 将通过Base64加密的字符串转换成对象
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="str"></param>
/// <returns></returns>
public static T DecryptBase64<T>(string str) where T : class
{
if (string.IsNullOrEmpty(str)) return default(T);
byte[] bytes = Convert.FromBase64String(str);
T t = SerializerHelper.ConvertToObject<T>(bytes);
return t;
}