MVC 皮肤实现

在利用ASP.NET MVC 框架编写程序时，有时我们需要根据业务自己选择视图模板存放的位置，比如针对用户的设置选择不同的皮肤。如下：

我们建一个 Themes/{Channel}/{Theme}/{Controller}/ {Action} 的存放路径，视图模板还用webform。在Url客户端的显示上，我们还遵循{Channel}/{Controller}/ {Action}规则。

实现思路是重写实现写一个ThemeViewEngine，实现IViewEngine，作用是选择正确的WebForumView 的路径。

看下实现代码:

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

namespace MvcApplicationTest.ThemeEngines
{
    /// <summary>
    /// 皮肤选择引擎
    /// </summary>
    public class ThemeViewEngine:IViewEngine
    {

        #region IViewEngine 成员

        public ViewEngineResult FindView(ControllerContext controllerContext, string viewName, string masterName, bool useCache)
        {
            return _FindView(controllerContext, viewName, null, useCache, "aspx");
        }

        public ViewEngineResult FindPartialView(ControllerContext controllerContext, string partialViewName, bool useCache)
        {
            return _FindView(controllerContext, partialViewName, null, useCache, "ascx");
        }

        public void ReleaseView(ControllerContext controllerContext, IView view)
        {
            IDisposable disposable = view as IDisposable;
            if (disposable != null)
                disposable.Dispose();
        }

        #endregion

        private ViewEngineResult _FindView(ControllerContext controllerContext, string viewName, string masterName, bool useCache, string ext)
        {
            if (controllerContext == null)
                throw new ArgumentNullException("controllerContext is required.", "controllerContext");
            if (string.IsNullOrEmpty(viewName))
                throw new ArgumentException("viewName is required.", "viewName");

            //当前不允许在Controller中指定View的masterName
            if (!string.IsNullOrEmpty(masterName))
            {
                throw new ArgumentException("不允许在Controller中指定View的masterName", "masterName");
            }

            string selectedThemeName = GetSelectedTheme(controllerContext);
            string controllerName = controllerContext.RouteData.Values["controller"].ToString();
            string viewPath = GetViewPath(controllerContext, selectedThemeName, controllerName, viewName, ext);
            if (viewPath == null)
                throw new InvalidOperationException(String.Format("The view '{0}' could not be located at these paths: {1}", viewName, GetChannelName(controllerContext)));

            return new ViewEngineResult(new WebFormView(viewPath, null), this);
        }

        #region Help Methods

        /// <summary>
        /// 获取皮肤文件路径
        /// </summary>
        private static string GetViewPath(ControllerContext controllerContext, string themeName, string controllerName, string viewName, string ext)
        {
            return String.Format(@"~/Themes/{0}/{1}/{2}/{3}.{4}", GetChannelName(controllerContext), themeName, controllerName, viewName, ext);
        }

        private static string GetChannelName(ControllerContext controllerContext)
        {
            if (controllerContext.RouteData.Values["channel"] == null)
            {
                return "";
            }
            else
            {
                return controllerContext.RouteData.Values["channel"].ToString();
            }
        }

        /// <summary>
        /// 获取需要显示的主题名称
        /// </summary>
        private static string GetSelectedTheme(ControllerContext controllerContext)
        {
            string themeName = "Default";
            if (GetChannelName(controllerContext).ToLower() == "channel")
            {
                themeName = "Default";
            }
            return themeName;
        }

        #endregion

    }
}

在应用时，还需配置Global

   routes.MapRoute(
               "Channel",                                              // Route name
               "{channel}/{controller}/{action}/{id}",                           // URL with parameters
               new { channel="Channel", controller = "Home", action = "Index", id = "" }  // Parameter defaults
           );

            ViewEngines.Engines.Add(new ThemeEngines.ThemeViewEngin