如何缓存返回图像在asp.net mvc的视图操作方法的输出？ [英] How to cache output of action method that returns image to the view in asp.net mvc?

问题描述

我读过很多有关缓存的职位了，但没有人其实完全匹配我的需求。在我的MVC 3应用程序我有一个动作方法的getImage（）返回图像类型的文件。然后，我用这个方法在一个视图中显示图片：

I've read lots of posts about caching already, but none of them actually match my needs exactly. In my mvc 3 app I have an action method GetImage() that returns a File of image type. Then I use this method in a view to display image:

<img width="75" height="75" src="@Url.Action("GetImage", "Store", new {productId = item.ProductId})"/>

我想在服务器上缓存图像。所以，我已经尝试过：

I want to cache images on a Server. So, what I've already tried:

1）使用OutputCacheAttribute：

1) to use OutputCacheAttribute:

    [HttpGet, OutputCache(Duration = 10, VaryByParam = "productId", Location = OutputCacheLocation.Server, NoStore = true)]
    public FileContentResult GetImage(int productId)
    {
        var p = _productRepository.GetProduct(productId);
        if (p != null)
        {
            if (System.IO.File.Exists(GetFullProductImagePath(productId)))
            {
                var image = Image.FromFile(GetFullProductImagePath(productId));
                return File(GetFileContents(image), "image/jpeg");
            }
        }
        var defaultPath = AppDomain.CurrentDomain.BaseDirectory +
                             ConfigurationManager.AppSettings["default-images-directory"];

        var defaultImage = Image.FromFile(Path.Combine(defaultPath, "DefaultProductImage.jpg"));
        return File(GetFileContents(defaultImage), "image/jpeg");
    }

图像不缓存（我得到的状态：200 OK）

Images are not cached (I get status: 200 OK)

2）使用以下Response.Cache方法中的getImage（）方法

2) to use the following Response.Cache methods in a GetImage() method:

    public FileContentResult GetImage(int productId)
    {
        Response.Cache.SetCacheability(HttpCacheability.Public);
        Response.Cache.SetMaxAge(new TimeSpan(0, 0, 0, 10));
        Response.Cache.SetExpires(DateTime.Now.Add(new TimeSpan(0, 0, 0, 10)));
        Response.Cache.AppendCacheExtension("must-revalidate, proxy-revalidate");        
        // other code is the same
    }

图像不缓存

3）在这里，我得到：304未修改，但的getImage（）方法返回什么（空图片）

3) Here I get: 304 Not Modified, but the GetImage() method returns nothing (empty image)

    public FileContentResult GetImage(int productId)
    {
        Response.StatusCode = 304;
        Response.StatusDescription = "Not Modified";
        Response.AddHeader("Content-Length", "0");     
        // other code is the same
    }

问：怎样缓存此操作方法的输出在服务器上

Question: How to cache the output of this action method on a server?

推荐答案

尝试这样的：

[HttpGet]
[OutputCache(
    Duration = 10, 
    VaryByParam = "productId", 
    Location = OutputCacheLocation.ServerAndClient)]
public ActionResult GetImage(string productId)
{
    ...
}

事情需要注意：使用 OutputCacheLocation.ServerAndClient 和摆脱了 NoStore = TRUE

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