问题是,我无法控制Response.OutputStream,如果我能够这样做,我将简单地根据结果流计算ETag。
我在WCF中做了这个事情,但是在MVC中找不到任何简单的想法。
我想要写这样的东西
[ETag] public ActionResult MyAction() { var myModel = Factory.CreateModel(); return View(myModel); }
任何想法?
解决方法
using System; using System.IO; using System.Security.Cryptography; using System.Web.Mvc; public class ETagAttribute : ActionFilterAttribute { private string GetToken(Stream stream) { MD5 md5 = MD5.Create(); byte [] checksum = md5.ComputeHash(stream); return Convert.ToBase64String(checksum,checksum.Length); } public override void OnResultExecuted(ResultExecutedContext filterContext) { filterContext.HttpContext.Response.AppendHeader("ETag",GetToken(filterContext.HttpContext.Response.OutputStream)); base.OnResultExecuted(filterContext); } }
这应该是有效的,但是不行。
显然,Microsoft overrode System.Web.HttpResponseStream.Read(Byte [] buffer,Int32 offset,Int32 count),以便它返回“Specified方法不受支持”,不知道为什么他们会这样做,因为它继承了System。 IO.Stream基类…
哪个是混合以下资源,Response.OutputStream是一个只写的流,所以我们必须使用一个Response.Filter类来读取输出流,一种古怪的,你必须在过滤器上使用一个过滤器,但是它的工作=)
http://bytes.com/topic/c-sharp/answers/494721-md5-encryption-question-communication-java
http://www.codeproject.com/KB/files/Calculating_MD5_Checksum.aspx
http://blog.gregbrant.com/post/Adding-Custom-HTTP-Headers-to-an-ASPNET-MVC-Response.aspx
http://www.infoq.com/articles/etags
http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html
更新
经过多次的战斗,我终于可以得到这个工作:
using System; using System.IO; using System.Security.Cryptography; using System.Web; using System.Web.Mvc; public class ETagAttribute : ActionFilterAttribute { public override void OnActionExecuting(ActionExecutingContext filterContext) { try { filterContext.HttpContext.Response.Filter = new ETagFilter(filterContext.HttpContext.Response); } catch (System.Exception) { // Do Nothing }; } } public class ETagFilter : MemoryStream { private HttpResponseBase o = null; private Stream filter = null; public ETagFilter (HttpResponseBase response) { o = response; filter = response.Filter; } private string GetToken(Stream stream) { byte[] checksum = new byte[0]; checksum = MD5.Create().ComputeHash(stream); return Convert.ToBase64String(checksum,checksum.Length); } public override void Write(byte[] buffer,int offset,int count) { byte[] data = new byte[count]; Buffer.BlockCopy(buffer,offset,data,count); filter.Write(data,count); o.AddHeader("ETag",GetToken(new MemoryStream(data))); } }
更多资源:
http://authors.aspalliance.com/aspxtreme/sys/Web/HttpResponseClassFilter.aspx
http://forums.asp.net/t/1380989.aspx/1