问自定义ViewEngine ASP.NET MVC 3

EN

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

namespace Milkshake.Commerce.MvcClient.ViewEngines
{
    /// <summary>
    /// Milkshake Commerce specific ViewEngine.
    /// </summary>
    public class MilkshakeViewEngine : WebFormViewEngine
    {
        /// <summary>
        /// Initializes a new instance of the <see cref="MilkshakeViewEngine"/> class.
        /// </summary>
        public MilkshakeViewEngine()
        {
            string themeName = AppData.ThemeName;

            var masterLocationFormats = new List<string>();
            masterLocationFormats.Add("~/Views/Themes/" + themeName + "/{0}.master");
            masterLocationFormats.AddRange(MasterLocationFormats);

            MasterLocationFormats = masterLocationFormats.ToArray();

            var partialViewLocationFormats = new List<string>();
            partialViewLocationFormats.Add("~/Views/Themes/" + themeName + "/{1}/{0}.aspx");
            partialViewLocationFormats.Add("~/Views/Themes/" + themeName + "/{1}/{0}.ascx");
            partialViewLocationFormats.Add("~/Views/Themes/" + themeName + "/{0}.aspx");
            partialViewLocationFormats.Add("~/Views/Themes/" + themeName + "/{0}.ascx");
            partialViewLocationFormats.AddRange(PartialViewLocationFormats);

            PartialViewLocationFormats = partialViewLocationFormats.ToArray();

            var viewLocationFormats = new List<string>();
            viewLocationFormats.Add("~/Views/Themes/" + themeName + "/{1}/{0}.aspx");
            viewLocationFormats.Add("~/Views/Themes/" + themeName + "/{1}/{0}.ascx");
            viewLocationFormats.Add("~/Views/Themes/" + themeName + "/{0}.aspx");
            viewLocationFormats.Add("~/Views/Themes/" + themeName + "/{0}.ascx");
            viewLocationFormats.AddRange(ViewLocationFormats);

            ViewLocationFormats = viewLocationFormats.ToArray();
        }

        /// <summary>
        /// Gets the user-selected <see cref="UserExperiences"/> setting, or returns the defualt if no experience has been selected.
        /// </summary>
        /// <returns>Returns the user experience selected by the user.</returns>
        public static UserExperiences GetUserExperienceSelected()
        {
            HttpContext context = HttpContext.Current;
            UserExperiences userExperience = context.Request.Browser.IsMobileDevice ? UserExperiences.Mobile : UserExperiences.Desktop;
            var userExperienceCookie = context.Request.Cookies["UserExperience"];

            if (userExperienceCookie != null)
            {
                if (!String.IsNullOrWhiteSpace(userExperienceCookie.Value))
                {
                    Enum.TryParse<UserExperiences>(userExperienceCookie.Value, out userExperience);
                }
            }
            else
            {
                SetUserExperience(userExperience);
            }

            return userExperience;
        }

        /// <summary>
        /// Sets the user experience cookie.
        /// </summary>
        /// <param name="experience">The user experience.</param>
        public static void SetUserExperience(UserExperiences experience)
        {
            HttpContext context = HttpContext.Current;
            HttpCookie userExperienceCookie = context.Request.Cookies["UserExperience"];

            if (userExperienceCookie == null)
            {
                userExperienceCookie = new HttpCookie("UserExperience");
            }

            userExperienceCookie.Value = experience.ToString();
            userExperienceCookie.Path = "/";
            userExperienceCookie.Expires = DateTime.UtcNow.AddDays(30);

            context.Response.Cookies.Add(userExperienceCookie);
        }

        /// <summary>
        /// Finds the specified view by using the specified controller context and master view name.
        /// </summary>
        /// <remarks>This override is used to determine if the browser is a mobile phone.
        /// If so, and it is supported, we add the phone specific folder/view name to the existing viewname,
        /// which forces the ViewManager to find a Theme specific mobile view (specific for that phone), or just use the built in mobile view.</remarks>
        /// <param name="controllerContext">The controller context.</param>
        /// <param name="viewName">The name of the view.</param>
        /// <param name="masterName">The name of the master view.</param>
        /// <param name="useCache">true to use the cached view.</param>
        /// <returns>The page view.</returns>
        /// <exception cref="T:System.ArgumentNullException">The <paramref name="controllerContext"/> parameter is null (Nothing in Visual Basic).</exception>
        /// <exception cref="T:System.ArgumentException">The <paramref name="viewName"/> parameter is null or empty.</exception>
        public override ViewEngineResult FindView(ControllerContext controllerContext, string viewName, string masterName, bool useCache)
        {
            ViewEngineResult result = null;
            var request = controllerContext.HttpContext.Request;
            var userExperience = GetUserExperienceSelected();

            // Avoid unnecessary checks if this device isn't suspected to be a mobile device
            if (userExperience == UserExperiences.Mobile)
            {
                masterName = "Mobile/Mobile";
                result = base.FindView(controllerContext, "Mobile/" + viewName, masterName, useCache);
            }

            // Fall back to desktop view if no other view has been selected
            if (result == null || result.View == null)
            {
                result = base.FindView(controllerContext, viewName, masterName, useCache);
            }

            return result;
        }

        /// <summary>
        /// Adds the default mobile location formats.
        /// </summary>
        /// <param name="defaultLocationFormats">The default location formats.</param>
        /// <param name="viewLocationFormats">The view location formats.</param>
        private void AddDefaultMobileLocationFormats(string[] defaultLocationFormats, List<string> viewLocationFormats)
        {
            var mobileViewLocationFormats = new List<string>();

            foreach (var item in defaultLocationFormats)
            {
                if (item.Contains("Views/{1}/{0}"))
                {
                    mobileViewLocationFormats.Add(item.Replace("/{1}/{0}", "/{1}/Mobile/{0}"));
                }
                else if (item.Contains("Views/Shared/{0}"))
                {
                    mobileViewLocationFormats.Add(item.Replace("/Shared/{0}", "/Shared/Mobile/{0}"));
                }
            }

            viewLocationFormats.AddRange(mobileViewLocationFormats);
        }
    }
}