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ASP.NET MVC - 定制属于你自己的ViewEngine

时间:2016-09-12 18:36:24      阅读:141      评论:0      收藏:0      [点我收藏+]

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http://blog.csdn.net/jackvs/article/details/7788743

ASP.NET MVC出来这么久了,心中却又很多的疑惑:为什么所有的View都要放在Views目录下? 为什么Shared文件夹下面的页面可以被共享? 为什么Page既可以是*.cshtml,也可以是*.aspx? 

其实上面的几个问题归结起来都是视图引擎的功效。

在传统的ASP.NET中,可能还没有ViewEngine的概念。因为在Web From里面,实现Page实现了IHttpHanlder的接口,所以Page既是响应的处理类,也是视图的渲染类。在ASP.NET MVC中,视图的概念被抽象了出来,试图引擎的概念也被抽象成了一个接口。

首先来看一下IViewEngine接口的定义:

 

namespace System.Web.Mvc
{
    public interface IViewEngine
    {
        ViewEngineResult FindPartialView(ControllerContext controllerContext, string partialViewName, bool useCache);
        ViewEngineResult FindView(ControllerContext controllerContext, string viewName, string masterName, bool useCache);
        void ReleaseView(ControllerContext controllerContext, IView view);
    }
}


总共3个函数,总结起来大概就是两个功能:Find & Release。

 


默认情况下,ASP.NET MVC提供了两个视图引擎:WebFormViewEngine和RazorViewEngine。

 

namespace System.Web.Mvc
{
    public static class ViewEngines
    {
        private static readonly ViewEngineCollection _engines = new ViewEngineCollection
        {
            new WebFormViewEngine(),
            new RazorViewEngine(),
        };

        public static ViewEngineCollection Engines
        {
            get { return _engines; }
        }
    }
}


这就是为什么ASP.NET MVC既支持*.aspx,又支持*.cshtml的原因了(个人觉得如果已经确定要使用RazorView的话,不如把WebFormViewEngine给移除,可能对性能会有所帮助)。

 

那为什么所有的视图都要放在Views目录下呢,这个就要拜RazorViewngines所赐了。

下面是RazorViewEngine的构造函数:

 

        public RazorViewEngine(IViewPageActivator viewPageActivator)
            : base(viewPageActivator)
        {
            AreaViewLocationFormats = new[]
            {
                "~/Areas/{2}/Views/{1}/{0}.cshtml",
                "~/Areas/{2}/Views/{1}/{0}.vbhtml",
                "~/Areas/{2}/Views/Shared/{0}.cshtml",
                "~/Areas/{2}/Views/Shared/{0}.vbhtml"
            };
            AreaMasterLocationFormats = new[]
            {
                "~/Areas/{2}/Views/{1}/{0}.cshtml",
                "~/Areas/{2}/Views/{1}/{0}.vbhtml",
                "~/Areas/{2}/Views/Shared/{0}.cshtml",
                "~/Areas/{2}/Views/Shared/{0}.vbhtml"
            };
            AreaPartialViewLocationFormats = new[]
            {
                "~/Areas/{2}/Views/{1}/{0}.cshtml",
                "~/Areas/{2}/Views/{1}/{0}.vbhtml",
                "~/Areas/{2}/Views/Shared/{0}.cshtml",
                "~/Areas/{2}/Views/Shared/{0}.vbhtml"
            };

            ViewLocationFormats = new[]
            {
                "~/Views/{1}/{0}.cshtml",
                "~/Views/{1}/{0}.vbhtml",
                "~/Views/Shared/{0}.cshtml",
                "~/Views/Shared/{0}.vbhtml"
            };
            MasterLocationFormats = new[]
            {
                "~/Views/{1}/{0}.cshtml",
                "~/Views/{1}/{0}.vbhtml",
                "~/Views/Shared/{0}.cshtml",
                "~/Views/Shared/{0}.vbhtml"
            };
            PartialViewLocationFormats = new[]
            {
                "~/Views/{1}/{0}.cshtml",
                "~/Views/{1}/{0}.vbhtml",
                "~/Views/Shared/{0}.cshtml",
                "~/Views/Shared/{0}.vbhtml"
            };

            FileExtensions = new[]
            {
                "cshtml",
                "vbhtml",
            };
        }


所有的寻址路径都被格式化了,是不是很眼熟呢,关于这里为啥用数组而不用List,个人觉得,数组的寻址效率要更高些,遍历速度更快。

 

好了,找了“罪魁祸首”,就好好地调教一个,让它乖乖听话,小样让去哪就去哪里。

 

namespace MvcApplicatin.Web.Mvc.ViewEngine
{
    public sealed class CustomViewEngine : RazorViewEngine
    {

        public CustomViewEngine()
        {
            ViewLocationFormats = new[]
            {
                "~/Views/{1}/{0}.cshtml",
                "~/Views/Shared/{0}.cshtml",
                "~/CustomViewLocation/{1}/{0}.cshtml"
            };
        }
        public override ViewEngineResult FindView(ControllerContext controllerContext, string viewName, string masterName, bool useCache)
        {
            return base.FindView(controllerContext, viewName, masterName, useCache);
        }
    }
}


我使用开发语言是C#,视图是Razor,所以稍稍修改了下ViewLocationFormats,让寻址路径能够寻到CustomViewLocation下面的视图。

 

接下去就很简单了,只需要把原来的视图引擎清空,加载自己的视图引擎就可以了。

 

        protected void Application_Start()
        {
            AreaRegistration.RegisterAllAreas();

            ViewEngines.Engines.Clear();

            ViewEngines.Engines.Add(new CustomViewEngine());

            RegisterGlobalFilters(GlobalFilters.Filters);
            RegisterRoutes(RouteTable.Routes);
        }


 



 

ASP.NET MVC - 定制属于你自己的ViewEngine

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原文地址:http://www.cnblogs.com/xdot/p/5865560.html

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