ASP.NET MVC“Donut caching”和TempData

主要思想是在缓存中保存TempData的副本,并在每个请求中进行检索.该解决方案是自定义TempDataProvider和简单http模块的组合.另外还有几个助手和静态类.

这是代码：

CustomTempDataProvider：

using System;
using System.Collections.Generic;
using System.Web;
using System.Web.Caching;
using System.Web.Mvc;

public class CustomTempDataProvider : SessionStateTempDataProvider,IHttpModule
{
    public void Init(HttpApplication application)
    {
        application.BeginRequest += new EventHandler(application_BeginRequest);
    }

    void application_BeginRequest(object sender,EventArgs e)
    {
        var httpContext = HttpContext.Current;
        var tempData = httpContext.Cache[TempDataKey] ?? new Dictionary<string,object>(StringComparer.OrdinalIgnoreCase);
        httpContext.Items.Add("TempData",tempData);
        httpContext.Cache.Remove(TempDataKey);
    }

    public override void SaveTempData(ControllerContext controllerContext,IDictionary<string,object> values)
    {
        HttpContext.Current.Cache.Insert(TempDataKey,values,null,DateTime.Now.AddMinutes(5),Cache.NoSlidingExpiration,CacheItemPriority.NotRemovable,null);
        base.SaveTempData(controllerContext,values);
    }

    public static string TempDataKey
    {
        get
        {
            string sessionID = "0";
            var httpContext = HttpContext.Current;
            if(httpContext.Session != null)
            {
                sessionID = httpContext.Session.SessionID;
            }
            else if (httpContext.Request.Cookies["ASP.NET_SessionId"] != null)
            {
                sessionID = httpContext.Request.Cookies["ASP.NET_SessionId"].Value;
            }
            return "TempData-For-Session-" + sessionID;
        }
    }

    public void Dispose()
    {
    }
}

在web.config中注册它：

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
    <system.web>
        <httpModules>
            <add name="CustomTempDataProvider" type="CustomTempDataProvider" />
        </httpModules>
    </system.web>
    <system.webServer>
        <modules>
            <remove name="CustomTempDataProvider" />
            <add name="CustomTempDataProvider" type="CustomTempDataProvider" />
        </modules>
    </system.webServer>
</configuration>

CustomControllerFactory：

using System.Web.Routing;
using System.Web.Mvc;

public class CustomControllerFactory : DefaultControllerFactory
{
    public override IController CreateController(
        RequestContext requestContext,string controllerName)
    {
        var controller = (Controller)base.CreateController(requestContext,controllerName);
        controller.TempDataProvider = new CustomTempDataProvider();
        return controller;
    }
}

在Global.asax中注册它：

protected void Application_Start()
{
    RegisterRoutes(RouteTable.Routes);

    ControllerBuilder.Current.SetControllerFactory(typeof(CustomControllerFactory));
}

用于访问TempData的静态类：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

public static class CustomTempData
{
    public static object Get(string key)
    {
        var tempData = HttpContext.Current.Items["TempData"] as IDictionary<string,object>;
        var item = tempData.FirstOrDefault(x => x.Key == key).Value ?? String.Empty;
        return item;
    }
}

用于缓存后替换的助手：

using System;
using System.Web;
using System.Web.Mvc;

public static class Html
{
    public delegate object MvcResponseSubstitutionCallback(HttpContextBase context);

    public static object MvcResponseSubstitute(this HtmlHelper html,MvcResponseSubstitutionCallback callback)
    {
        html.ViewContext.HttpContext.Response.WriteSubstitution(
            context =>
                HttpUtility.HtmlEncode(
                    (callback(new HttpContextWrapper(context)) ?? String.Empty).ToString()
                )
            );

        return null;
    }
}

现在这成功了：

<h3><%= Html.MvcResponseSubstitute(context => CustomTempData.Get("message")) %></h3>

如果您了解俄语,请阅读this

希望这可以帮助