示例控制器：

public class FooController : Controller
 {
    public ActionResult MyAction()
    {
       return new HttpStatusCodeResult((int)HttpStatusCode.BadRequest,"Foo \n Bar");
    }
 }

示例客户端：

using (WebClient client = new WebClient())
{
   client.DownloadString("http://localhost/app/Foo/MyAction");
}

抛出异常：

System.Net.WebException: The underlying connection was closed: An unexpected error occurred on a receive. 
  System.IO.IOException: Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host.
    System.Net.Sockets.SocketException: An existing connection was forcibly closed by the remote host

使用curl时的行为是一致的(curl 7.25.0(i386-pc-win32)libcurl / 7.25.0 zlib / 1.2.6)

curl http://localhost/app/Foo/MyAction

卷曲：(56)Recv失败：重置连接

编辑

我最终使用这个自定义ActionResult来获得所需的结果.

public class BadRequestResult : ActionResult
{
   private const int BadRequestCode = (int)HttpStatusCode.BadRequest;
   private int count = 0;

   public BadRequestResult(string errors)
      : this(errors,"")
   {
   }

   public BadRequestResult(string format,params object[] args)
   {
      if (String.IsNullOrEmpty(format))
      {
         throw new ArgumentException("format");
      }

      Errors = String.Format(format,args);

      count = Errors.Split(new string[] { Environment.NewLine },StringSplitOptions.RemoveEmptyEntries).Length;
   }

   public string Errors { get; private set; }

   public override void ExecuteResult(ControllerContext context)
   {
      if (context == null)
      {
         throw new ArgumentNullException("context");
      }

      HttpResponseBase response = context.HttpContext.Response;
      response.TrySkipIisCustomErrors = true;
      response.StatusCode = BadRequestCode;
      response.StatusDescription = String.Format("Bad Request {0} Error(s)",count);
      response.Write(Errors);
      response.End();
   }
}