public class CustomerException : System.Exception{public CustomerException(){}public CustomerException(string message) : base(message){}public CustomerException(string message, params object[] args) : base(string.Format(message, args)){}}

　　[BaseException]public class DefaultController : Controller{// GET: Defaultpublic ActionResult Index(){return View();}public JsonResult Login(string userName, string password){if (userName == "admin" && password == "admin"){return Json(true, JsonRequestBehavior.AllowGet);}else{throw new CustomerException("用户名或者密码错误");}}}public class BaseExceptionAttribute : HandleErrorAttribute{public override void OnException(ExceptionContext filterContext){if (filterContext.HttpContext.Request.IsAjaxRequest() && filterContext.Exception is CustomerException){filterContext.ExceptionHandled = true;filterContext.HttpContext.Response.StatusCode = (int)System.Net.HttpStatusCode.BadRequest;var result = new ContentResult() { Content = filterContext.Exception.Message, ContentType = MediaTypeNames.Text.Plain };filterContext.Result = result;}else{//记录日志
            }base.OnException(filterContext);}}

@{ViewBag.Title = "Index";
}用户名：<input type="text" id="username"/>
密码  ：<input type="text" id="password"/>
<button id="btnAjaxError" type="button">登陆</button>
@section Script
{<script type="text/javascript">$(function () {$("#btnAjaxError").click(function () {$.ajax({url:"/Default/Login",data: { userName: $('#username').val(), password: $('#password').val() },type: 'post'}).done(function (data) {console.log("successful:"+data);}).fail(function (a, b, c) {debugger;console.log("fail:"+a.responseText);});});});
</script>
}

<customErrors mode="On"></customErrors>

　　public class BaseExceptionAttribute : HandleErrorAttribute{public override void OnException(ExceptionContext filterContext){base.OnException(filterContext);if (filterContext.HttpContext.Request.IsAjaxRequest() && filterContext.Exception is CustomerException){filterContext.ExceptionHandled = true;filterContext.HttpContext.Response.StatusCode = (int)System.Net.HttpStatusCode.BadRequest;var result = new ContentResult() { Content = filterContext.Exception.Message, ContentType = MediaTypeNames.Text.Plain };filterContext.Result = result;}else{//记录日志
            }}}