ASP。NET MVC图像参数缓存

因此,无论参数值如何,通过调用操作返回的图像总是相同的。有办法解决这个问题吗?

public class ImageResult : ActionResult  
{  
    public Image Image  
    {  
        get; set;  
    }  

    public ImageFormat ImageFormat  
    {  
        get; set;  
    }  

    private static Dictionary FormatMap  
    {  
        get; set;  
    }  

    static ImageResult()  
    {  
        CreateContentTypeMap();  
    }  

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

        context.HttpContext.Response.Clear();  
        context.HttpContext.Response.ContentType = FormatMap[ImageFormat];  

        Image.Save(context.HttpContext.Response.OutputStream, ImageFormat);  
    }  

    private static void CreateContentTypeMap()  
    {  
        FormatMap = new Dictionary  
        {  
            { ImageFormat.Bmp,  "image/bmp"                },  
            { ImageFormat.Gif,  "image/gif"                },  
            { ImageFormat.Icon, "image/vnd.microsoft.icon" },  
            { ImageFormat.Jpeg, "image/Jpeg"               },  
            { ImageFormat.Png,  "image/png"                },  
            { ImageFormat.Tiff, "image/tiff"               },  
            { ImageFormat.Wmf,  "image/wmf"                }  
        };  
    }  
}  

以及控制器动作:

public ActionResult GetCalendarBadge(DateTime displayDate)
{
    var bmp = SomeBitmap();
    var g = Graphics.FromImage(bmp);

    //GDI+ to draw the image.

    return new ImageResult { Image = bmp, ImageFormat = ImageFormat.Png };
}

<% foreach(var item in this.Model.News) { %>  
      <%= Html.Image<NewsController>(o => o.GetCalendarBadge(item.DisplayDate), 75, 75)%>
<% } %>

  context.HttpContext.Response.Cache.SetNoStore();  
  context.HttpContext.Response.Expires = 0;  
  context.HttpContext.Response.AppendHeader("Pragma", "no-cache");