/// <summary>
    /// ASP.NET4.0 表单验证类
    /// </summary>
    public class FormRequestValidation : RequestValidator
    {
        public FormRequestValidation() { }

        protected override bool IsValidRequestString(HttpContext context, string value, RequestValidationSource requestValidationSource
            , string collectionKey, out int validationFailureIndex)
        {
            //不验证
            validationFailureIndex = -1; return true;
        }

    }

  <system.web>
    <!--new 添加该节点对request.form的验证进行设定 -->
    <httpRuntime requestValidationType="namespace.FormRequestValidation" />
  </system.web>