Asp.net 图像的通用处理程序（ashx）-非常慢，除非先写入图像

多年来，我一直在从SQLServer渲染二进制图像，但通常只渲染非常小的图像。最近，我想对更大的图像（500kb大小）执行此操作

我发现我以前的方法需要很长的时间（45秒）来渲染图像。新方法很快。我在下面介绍了这两种方法。你知道为什么第一个这么慢吗？我应该提到，我更喜欢原始的图像呈现方式，因为它与内容类型无关

在这两种情况下，ImageData在sql server 2008中都存储为varbinary

慢行方式

        context.Response.Clear();
        context.Response.ContentType = user.ImageContentType;

        context.Response.Cache.SetCacheability(HttpCacheability.Public);
        context.Response.Cache.SetMaxAge(new TimeSpan(0, 5, 0));

        context.Response.OutputStream.Write((byte[])user.ImageData, 0, user.ImageData.Length);
        context.Response.End();

            context.Response.Cache.SetCacheability(HttpCacheability.Public);
            context.Response.Cache.SetMaxAge(new TimeSpan(0, 5, 0));

            MemoryStream memoryStream = new MemoryStream((byte[])prm.ImageData, false);
            System.Drawing.Image imgFromGB = System.Drawing.Image.FromStream(memoryStream);
            imgFromGB.Save(context.Response.OutputStream, System.Drawing.Imaging.ImageFormat.Jpeg);

            context.Response.Cache.SetCacheability(HttpCacheability.Public);
            context.Response.Cache.SetMaxAge(new TimeSpan(0, 5, 0));

快速方式

        context.Response.Clear();
        context.Response.ContentType = user.ImageContentType;

        context.Response.Cache.SetCacheability(HttpCacheability.Public);
        context.Response.Cache.SetMaxAge(new TimeSpan(0, 5, 0));

        context.Response.OutputStream.Write((byte[])user.ImageData, 0, user.ImageData.Length);
        context.Response.End();

            context.Response.Cache.SetCacheability(HttpCacheability.Public);
            context.Response.Cache.SetMaxAge(new TimeSpan(0, 5, 0));

            MemoryStream memoryStream = new MemoryStream((byte[])prm.ImageData, false);
            System.Drawing.Image imgFromGB = System.Drawing.Image.FromStream(memoryStream);
            imgFromGB.Save(context.Response.OutputStream, System.Drawing.Imaging.ImageFormat.Jpeg);

            context.Response.Cache.SetCacheability(HttpCacheability.Public);
            context.Response.Cache.SetMaxAge(new TimeSpan(0, 5, 0));

---

顺便说一下，确切的图像大小是：356081，内容类型是：image/jpeg