/// <summary>
 /// 验证码
 /// </summary>
 /// <returns></returns>
 public string VerifyCode()
 {
     return(ImgVerifyCodeHelper.BuildVerifyCode(4));
 }
 /// <summary>
 /// 验证码
 /// </summary>
 /// <returns></returns>
 public byte[] VerifyCodeByte()
 {
     return(ImgVerifyCodeHelper.BuildVerifyCodeByte(4));
 }