ASP.NET MVC 修改视图的默认路径

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ASP.NET MVC 修改视图的默认路径

本章将和大家分享如何在ASP.NET MVC中修改视图的默认路径。在此之前，首先我们要搞懂MVC它是怎么搜索视图的。

先来看下Demo的目录结构：

本Demo的Web项目为ASP.NET Web 应用程序（目标框架为.NET Framework 4.5） MVC项目。

了解MVC的人应该都知道，在Action中如果要返回一个页面，那我们一般的做法都是去调用View方法，如下所示：

接下来我们就通过反编译工具来看一下这个View方法里面到底都做了啥：

可以看到它最后返回的是 ViewResult 对象，我们继续通过反编译工具来看一下这个 ViewResult 类：

可以发现，它是从 base.ViewEngineCollection 中找默认视图的，下面我们继续通过反编译工具找到 base.ViewEngineCollection ，如下所示：

可以看到，其实它返回的就是一个 ViewEngineCollection 视图引擎集合，并且它的取值来自 ViewEngines.Engines ，我们点击 Engines 往里找：

继续点击 _engines 往里找：

找到最后我们可以发现，其实 ViewEngines.Engines 里面存放的就是 new WebFormViewEngine() 和 new RazorViewEngine() 。

我们通过反编译工具找到 RazorViewEngine 这个类，如下所示：

using System;

namespace System.Web.Mvc
{
    /// <summary>Represents a view engine that is used to render a Web page that uses the ASP.NET Razor syntax.</summary>
    public class RazorViewEngine : BuildManagerViewEngine
    {
        internal static readonly string ViewStartFileName = "_ViewStart";

        /// <summary>Initializes a new instance of the <see cref="T:System.Web.Mvc.RazorViewEngine" /> class.</summary>
        public RazorViewEngine() : this(null)
        {
        }

        /// <summary>Initializes a new instance of the <see cref="T:System.Web.Mvc.RazorViewEngine" /> class using the view page activator.</summary>
        /// <param name="viewPageActivator">The view page activator.</param>
        public RazorViewEngine(IViewPageActivator viewPageActivator) : base(viewPageActivator)
        {
            base.AreaViewLocationFormats = new string[]
            {
                "~/Areas/{2}/Views/{1}/{0}.cshtml",
                "~/Areas/{2}/Views/{1}/{0}.vbhtml",
                "~/Areas/{2}/Views/Shared/{0}.cshtml",
                "~/Areas/{2}/Views/Shared/{0}.vbhtml"
            };
            base.AreaMasterLocationFormats = new string[]
            {
                "~/Areas/{2}/Views/{1}/{0}.cshtml",
                "~/Areas/{2}/Views/{1}/{0}.vbhtml",
                "~/Areas/{2}/Views/Shared/{0}.cshtml",
                "~/Areas/{2}/Views/Shared/{0}.vbhtml"
            };
            base.AreaPartialViewLocationFormats = new string[]
            {
                "~/Areas/{2}/Views/{1}/{0}.cshtml",
                "~/Areas/{2}/Views/{1}/{0}.vbhtml",
                "~/Areas/{2}/Views/Shared/{0}.cshtml",
                "~/Areas/{2}/Views/Shared/{0}.vbhtml"
            };
            base.ViewLocationFormats = new string[]
            {
                "~/Views/{1}/{0}.cshtml",
                "~/Views/{1}/{0}.vbhtml",
                "~/Views/Shared/{0}.cshtml",
                "~/Views/Shared/{0}.vbhtml"
            };
            base.MasterLocationFormats = new string[]
            {
                "~/Views/{1}/{0}.cshtml",
                "~/Views/{1}/{0}.vbhtml",
                "~/Views/Shared/{0}.cshtml",
                "~/Views/Shared/{0}.vbhtml"
            };
            base.PartialViewLocationFormats = new string[]
            {
                "~/Views/{1}/{0}.cshtml",
                "~/Views/{1}/{0}.vbhtml",
                "~/Views/Shared/{0}.cshtml",
                "~/Views/Shared/{0}.vbhtml"
            };
            base.FileExtensions = new string[]
            {
                "cshtml",
                "vbhtml"
            };
        }

        /// <summary>Creates a partial view using the specified controller context and partial path.</summary>
        /// <returns>The partial view.</returns>
        /// <param name="controllerContext">The controller context.</param>
        /// <param name="partialPath">The path to the partial view.</param>
        protected override IView CreatePartialView(ControllerContext controllerContext, string partialPath)
        {
            return new RazorView(controllerContext, partialPath, null, false, base.FileExtensions, base.ViewPageActivator)
            {
                DisplayModeProvider = base.DisplayModeProvider
            };
        }

        /// <summary>Creates a view by using the specified controller context and the paths of the view and master view.</summary>
        /// <returns>The view.</returns>
        /// <param name="controllerContext">The controller context.</param>
        /// <param name="viewPath">The path to the view.</param>
        /// <param name="masterPath">The path to the master view.</param>
        protected override IView CreateView(ControllerContext controllerContext, string viewPath, string masterPath)
        {
            return new RazorView(controllerContext, viewPath, masterPath, true, base.FileExtensions, base.ViewPageActivator)
            {
                DisplayModeProvider = base.DisplayModeProvider
            };
        }
    }
}

你会惊奇的发现，上面描述的路径就是我们MVC默认的视图路径。既然如此，那我们大概知道了，将来如果要做一些扩展（例如：修改MVC默认的视图路径），就可以从这个类入手。

话不多说，下面我们就重点来看下如何修改MVC默认的视图路径？

我们先来验证下 ViewEngines.Engines 里面存放的到底是不是只有 new WebFormViewEngine() 和 new RazorViewEngine() ，如下所示：

通过调试 Global.asax 中 Application_Start 方法，我们可以发现 ViewEngines.Engines 里面存的确实只有 new WebFormViewEngine() 和 new RazorViewEngine() ，那么下面我们就可以大胆的去扩展了。

首先自定义一个Razor视图引擎，如下所示：

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

namespace ViewEngineExtend.ViewEngineExtend
{
    /// <summary>
    /// 自定义Razor视图引擎
    /// </summary>
    public class CustomRazorViewEngine : RazorViewEngine
    {
        #region 构造函数

        public CustomRazorViewEngine()
            : this(null)
        {

        }

        public CustomRazorViewEngine(IViewPageActivator viewPageActivator)
            : base(viewPageActivator)
        {

        }

        #endregion 构造函数

        public override ViewEngineResult FindView(ControllerContext controllerContext, string viewName, string masterName, bool useCache)
        {
            if (controllerContext.HttpContext.Request.UserAgent.Contains("Chrome"))
            {
                this.SetTheme("Chrome");
            }
            else
            {
                this.SetTheme(""); //一定得有，因为只有一个Engines实例
            }

            return base.FindView(controllerContext, viewName, masterName, useCache);
        }

        public override ViewEngineResult FindPartialView(ControllerContext controllerContext, string partialViewName, bool useCache)
        {
            if (controllerContext.HttpContext.Request.UserAgent.Contains("Chrome"))
            {
                this.SetTheme("Chrome");
            }
            else
            {
                this.SetTheme(""); //一定得有，因为只有一个Engines实例
            }

            return base.FindPartialView(controllerContext, partialViewName, useCache);
        }

        /// <summary>
        /// 设置主题（修改视图的默认路径）
        /// </summary>
        /// <param name="browser">浏览器</param>
        void SetTheme(string browser)
        {
            if (!string.IsNullOrEmpty(browser) && browser.Contains("Chrome"))
            {
                base.AreaViewLocationFormats = new string[]
                {
                    "~/Areas/{2}/ChromeViews/{1}/{0}.cshtml",
                    "~/Areas/{2}/ChromeViews/{1}/{0}.vbhtml",
                    "~/Areas/{2}/ChromeViews/Shared/{0}.cshtml",
                    "~/Areas/{2}/ChromeViews/Shared/{0}.vbhtml"
                };
                base.AreaMasterLocationFormats = new string[]
                {
                    "~/Areas/{2}/ChromeViews/{1}/{0}.cshtml",
                    "~/Areas/{2}/ChromeViews/{1}/{0}.vbhtml",
                    "~/Areas/{2}/ChromeViews/Shared/{0}.cshtml",
                    "~/Areas/{2}/ChromeViews/Shared/{0}.vbhtml"
                };
                base.AreaPartialViewLocationFormats = new string[]
                {
                    "~/Areas/{2}/ChromeViews/{1}/{0}.cshtml",
                    "~/Areas/{2}/ChromeViews/{1}/{0}.vbhtml",
                    "~/Areas/{2}/ChromeViews/Shared/{0}.cshtml",
                    "~/Areas/{2}/ChromeViews/Shared/{0}.vbhtml"
                };
                base.ViewLocationFormats = new string[]
                {
                    "~/ChromeViews/{1}/{0}.cshtml",
                    "~/ChromeViews/{1}/{0}.vbhtml",
                    "~/ChromeViews/Shared/{0}.cshtml",
                    "~/ChromeViews/Shared/{0}.vbhtml"
                };
                base.MasterLocationFormats = new string[]
                {
                    "~/ChromeViews/{1}/{0}.cshtml",
                    "~/ChromeViews/{1}/{0}.vbhtml",
                    "~/ChromeViews/Shared/{0}.cshtml",
                    "~/ChromeViews/Shared/{0}.vbhtml"
                };
                base.PartialViewLocationFormats = new string[]
                {
                    "~/ChromeViews/{1}/{0}.cshtml",
                    "~/ChromeViews/{1}/{0}.vbhtml",
                    "~/ChromeViews/Shared/{0}.cshtml",
                    "~/ChromeViews/Shared/{0}.vbhtml"
                };
            }
            else
            {
                base.AreaViewLocationFormats = new string[]
                {
                    "~/Areas/{2}/Views/{1}/{0}.cshtml",
                    "~/Areas/{2}/Views/{1}/{0}.vbhtml",
                    "~/Areas/{2}/Views/Shared/{0}.cshtml",
                    "~/Areas/{2}/Views/Shared/{0}.vbhtml"
                };
                base.AreaMasterLocationFormats = new string[]
                {
                    "~/Areas/{2}/Views/{1}/{0}.cshtml",
                    "~/Areas/{2}/Views/{1}/{0}.vbhtml",
                    "~/Areas/{2}/Views/Shared/{0}.cshtml",
                    "~/Areas/{2}/Views/Shared/{0}.vbhtml"
                };
                base.AreaPartialViewLocationFormats = new string[]
                {
                    "~/Areas/{2}/Views/{1}/{0}.cshtml",
                    "~/Areas/{2}/Views/{1}/{0}.vbhtml",
                    "~/Areas/{2}/Views/Shared/{0}.cshtml",
                    "~/Areas/{2}/Views/Shared/{0}.vbhtml"
                };
                base.ViewLocationFormats = new string[]
                {
                    "~/Views/{1}/{0}.cshtml",
                    "~/Views/{1}/{0}.vbhtml",
                    "~/Views/Shared/{0}.cshtml",
                    "~/Views/Shared/{0}.vbhtml"
                };
                base.MasterLocationFormats = new string[]
                {
                    "~/Views/{1}/{0}.cshtml",
                    "~/Views/{1}/{0}.vbhtml",
                    "~/Views/Shared/{0}.cshtml",
                    "~/Views/Shared/{0}.vbhtml"
                };
                base.PartialViewLocationFormats = new string[]
                {
                    "~/Views/{1}/{0}.cshtml",
                    "~/Views/{1}/{0}.vbhtml",
                    "~/Views/Shared/{0}.cshtml",
                    "~/Views/Shared/{0}.vbhtml"
                };
                //base.FileExtensions = new string[]
                //{
                //    "cshtml",
                //    "vbhtml"
                //};
            }
        }
    }
}

接着修改 Global.asax 中 Application_Start 方法，将默认的 RazorViewEngine 替换成自定义的 CustomRazorViewEngine ，如下所示：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;
using System.Web.Optimization;
using System.Web.Routing;

using ViewEngineExtend.ViewEngineExtend;

namespace ViewEngineExtend
{
    public class MvcApplication : System.Web.HttpApplication
    {
        protected void Application_Start()
        {
            AreaRegistration.RegisterAllAreas();
            FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
            RouteConfig.RegisterRoutes(RouteTable.Routes);
            BundleConfig.RegisterBundles(BundleTable.Bundles);

            //var viewEngineCollection = ViewEngines.Engines;
            ViewEngines.Engines.Clear();
            ViewEngines.Engines.Add(new WebFormViewEngine());
            ViewEngines.Engines.Add(new CustomRazorViewEngine()); //替换成自定义的Razor视图引擎
        }
    }
}

此外，Demo中还准备了两套视图：

其中 ~/ChromeViews/Home/Index.cshtml 页面代码如下：

@{
    ViewBag.Title = "Home Page";
}

<h1>This is ChromeViews/Home/Index</h1>

其中 ~/Views/Home/Index.cshtml 页面代码如下：

@{
    ViewBag.Title = "Home Page";
}

<h1>This is Views/Home/Index</h1>

最后，我们分别使用谷歌浏览器和IE浏览器来访问 /Home/Index 页面，如下所示：

谷歌浏览器运行结果如下：

IE浏览器运行结果如下：

仔细观察后你会发现同样都是访问 /Home/Index 页面，但是这两个浏览器的运行结果却是不一样的，说明我们的视图引擎扩展成功了。

至此本文就全部介绍完了，如果觉得对您有所启发请记得点个赞哦！！！

Demo源码：

链接：https://pan.baidu.com/s/1TWVlsq98Sjt6qYOMXaTwCQ 
提取码：3nm2

此文由博主精心撰写转载请保留此原文链接：https://www.cnblogs.com/xyh9039/p/15240321.html

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