第四篇 基于.net搭建热插拔式web框架（RazorEngine实现）

　　在开头也是先给大家道个歉，由于最近准备婚事导致这篇文章耽误了许久，同时也谢谢老婆大人对我的支持。

　　回顾上篇文章，我们重造了一个controller，这个controller中用到了视图引擎，我们的视图引擎虽然也叫Razor，但此Razor非mvc中的Razor，MVC中的Razor同样依赖于HttpContext,我们实现的Razor借用 RazorEngine。关于RazorEngine的更多介绍请参阅http://antaris.github.io/RazorEngine/。

　　在上篇文章中无论是View方法还是PartialView方法，都用到了CompileView对象，我们先来看一下CompileView类的实现。

/// <summary>
    /// 视图编译类
    /// </summary>
    public class CompileView
    {
        private static Regex layoutEx = new Regex("Layout\\s*=\\s*@?\"(\\S*)\";");//匹配视图中的layout
        static InvalidatingCachingProvider cache = new InvalidatingCachingProvider();
        static FileSystemWatcher m_Watcher = new FileSystemWatcher();

        static CompileView()
        {
            var config = new TemplateServiceConfiguration();
            config.BaseTemplateType = typeof(HuberImplementingTemplateBase<>);
            config.ReferenceResolver = new HuberReferenceResolver();
            config.CachingProvider = cache;
            cache.InvalidateAll();
            Engine.Razor = RazorEngineService.Create(config);
            //添加文件修改监控，以便在cshtml文件修改时重新编译该文件
            m_Watcher.Path = HuberVariable.CurWebDir;
            m_Watcher.IncludeSubdirectories = true;
            m_Watcher.Filter = "*.*";
            m_Watcher.NotifyFilter = NotifyFilters.LastWrite | NotifyFilters.FileName;
            m_Watcher.Created += new FileSystemEventHandler(OnChanged);
            m_Watcher.Changed += new FileSystemEventHandler(OnChanged);
            m_Watcher.Deleted += new FileSystemEventHandler(OnChanged);

            m_Watcher.EnableRaisingEvents = true;
        }
        //当视图被修改后清除缓存
        private static void OnChanged(object sender, FileSystemEventArgs e)
        {
            if (e.FullPath.EndsWith(".cshtml"))
            {
                string s = e.FullPath.Replace(HuberVariable.CurWebDir, "/");

                var key = Engine.Razor.GetKey(s);
                cache.InvalidateCache(key);
            }

        }

        public CompileView()
        {
        }

        public string RunCompile(ITemplateKey key, Type modelType, object model, DynamicViewBag viewBag)
        {
            //判断唯一视图的缓存
            string path = (HuberVariable.CurWebDir + key.Name).Replace(@"\\", @"\");
            ICompiledTemplate cacheTemplate;
            cache.TryRetrieveTemplate(key, null, out cacheTemplate);
            if (cacheTemplate == null || !cacheTemplate.Key.Name.Trim().Equals(key.Name.Trim()))
            {
                CompileViewAndLayout(key, null, model, viewBag);
            }
            //当缓存存在返回结果
            return Engine.Razor.RunCompile(key, null, model, viewBag);
        }
        /// <summary>
        /// 编译视图和层layout
        /// </summary>
        /// <param name="key">视图的唯一路径</param>
        /// <param name="modelType">视图类型 :视图/layout</param>
        /// <param name="model">页面 MODEL</param>
        /// <param name="viewBag">viewBag</param>
        public void CompileViewAndLayout(ITemplateKey key, Type modelType, object model, DynamicViewBag viewBag)
        {
            //获取视图
            string FullPath = (HuberVariable.CurWebDir + key.Name.Replace("/", @"\")).Replace(@"\\", @"\");
            string content = System.IO.File.ReadAllText(FullPath);
            //匹配layout
            var matchs = layoutEx.Matches(content);
            string layoutPath = string.Empty;
            if (matchs != null)
            {

                foreach (Match m in matchs)
                {
                    layoutPath = m.Groups[1].Value;
                }
            }
            if (layoutPath != string.Empty)
            {
                //添加layout到模板
                string FullLayoutPath = (HuberVariable.CurWebDir + layoutPath.Replace("/", @"\")).Replace(@"\\", @"\");

                if (File.Exists(FullLayoutPath))
                {
                    ITemplateKey layoutKey = Engine.Razor.GetKey(layoutPath, ResolveType.Layout);
                    CompileViewAndLayout(layoutKey, null, model, viewBag);
                }
            }
            if (key.TemplateType == ResolveType.Layout)
            {
                Engine.Razor.AddTemplate(key, content);
            }
            else
            {
                //编译视图
                Engine.Razor.RunCompile(content, key, null, model);
            }

        }
    }

　　

　　InvalidatingCachingProvider是RazorEngine对视图文件编译结果的一种缓存策略，RazorEngine提供的缓存策略还有DefaultCachingProvider，也可以自己实现一种缓存策略只要继承ICachingProvider。

　　HuberImplementingTemplateBase：我们自定义的一种Razor模板标签，如“@Html.Raw”，这个例子也可以在RazorEngine官方文档中找到。我们还可以按照规则定义更多用法，下边是我的一些实现：

/// <summary>页面帮助类
    /// A simple helper demonstrating the @Html.Raw
    /// </summary>
    /// <typeparam name="T"></typeparam>
    public class HuberImplementingTemplateBase<T> : TemplateBase<T>
    {
        /// <summary>
        /// A simple helper demonstrating the @Html.Raw
        /// </summary>
        public HuberImplementingTemplateBase()
        {
            Html = new RazorHtmlHelper();
        }

        /// <summary>
        /// A simple helper demonstrating the @Html.Raw
        ///
        /// </summary>
        public RazorHtmlHelper Html { get; set; }

    }

public class RazorHtmlHelper
    {

        /// <summary>
        /// 调用Action视图
        /// </summary>
        /// <param name="actionName">action方法名称</param>
        /// <param name="controllerName">控制器名称</param>
        /// <returns></returns>
        public IEncodedString Action(string actionName, string controllerName)
        {
            return Action(actionName, controllerName, new { });

        }

        /// <summary>
        /// 调用Action视图
        /// </summary>
        /// <param name="actionName"></param>
        /// <param name="controllerName"></param>
        /// <param name="routeValues">传入参数</param>
        /// <returns></returns>
        public IEncodedString Action(string actionName, string controllerName, object routeValues)
        {
            RefRequestEntity paras = SetParamValue(routeValues);

            var t = HuberHttpModule.CurDomainAssembly.GetType(HuberHttpModule.CurDomainAssemblyName + ".Controllers." + controllerName + "Controller");
            var m = t.GetMethod(actionName);
            object dObj = Activator.CreateInstance(t);
            object result = m.Invoke(dObj, new object[] { paras });
            return new RawString((result as RefRespondEntity).ResultContext.ToString());
        }

        /// <summary>
        /// 根据model设置传入参数
        /// </summary>
        /// <param name="routeValues"></param>
        /// <returns></returns>
        private static RefRequestEntity SetParamValue(object routeValues)
        {
            RefRequestEntity paras = new RefRequestEntity();

            Type t1 = routeValues.GetType();
            PropertyInfo[] pis = t1.GetProperties();
            foreach (PropertyInfo pi in pis)
            {
                paras.Request.Add(pi.Name, pi.GetValue(routeValues));

            }
            return paras;
        }

        public IEncodedString RenderAction(string actionName, string controllerName)
        {
            return Action(actionName, controllerName, new { });
        }

        public IEncodedString RenderAction(string actionName, string controllerName, object routeValues)
        {
            return Action(actionName, controllerName, routeValues);
        }

        public IEncodedString RenderPartial(string partialViewName, string controllerName)
        {
            return RenderPartial(partialViewName, controllerName, new { }, new DynamicViewBag());
        }

        // Renders the partial view with the given view data and, implicitly, the given view data's model
        public IEncodedString RenderPartial(string partialViewName, string controllerName, DynamicViewBag ViewBag)
        {
            return RenderPartial(partialViewName, controllerName, new { }, ViewBag);
        }

        // Renders the partial view with an empty view data and the given model
        public IEncodedString RenderPartial(string partialViewName, string controllerName, object model)
        {
            return RenderPartial(partialViewName, controllerName, model, new DynamicViewBag());
        }

        // Renders the partial view with a copy of the given view data plus the given model
        /// <summary>
        /// 部分视图
        /// </summary>
        /// <param name="partialViewName">部分视图名称</param>
        /// <param name="controllerName">控制器名称</param>
        /// <param name="model"> model</param>
        /// <param name="ViewBag">ViewBag</param>
        /// <returns></returns>
        public IEncodedString RenderPartial(string partialViewName, string controllerName, object model, DynamicViewBag ViewBag)
        {

            RefRequestEntity paras = SetParamValue(model);

            var t = HuberHttpModule.CurDomainAssembly.GetType(HuberHttpModule.CurDomainAssemblyName + ".Controllers." + controllerName + "Controller");
            var ActionFunc = t.GetMethod(partialViewName);
            object dObj = Activator.CreateInstance(t);

            var AddViewBageFunc = t.GetMethod("AddViewBageValues");

            foreach (string key in ViewBag.GetDynamicMemberNames())
            {

                AddViewBageFunc.Invoke(dObj, new object[] { key, Impromptu.InvokeGet(ViewBag, key) });
            }

            object result = ActionFunc.Invoke(dObj, new object[] { paras });
            return new RawString((result as RefRespondEntity).ResultContext.ToString());
        }

    }

　　

　　　HuberReferenceResolver：我们定义的Razor中用的类库依赖。

public class HuberReferenceResolver : IReferenceResolver
    {

        static List<CompilerReference> compilerReference;
        static HuberReferenceResolver()
        {
            //加载本地所有类库,@using 使用
            compilerReference = new List<CompilerReference>();
            IEnumerable<string> loadedAssemblies = (new UseCurrentAssembliesReferenceResolver())
                .GetReferences(null, null)
                .Select(r => r.GetFile())
                .ToArray();
            foreach (var l in loadedAssemblies)
            {
                compilerReference.Add(CompilerReference.From(l));
            }

        }

        public string FindLoaded(IEnumerable<string> refs, string find)
        {
            return refs.First(r => r.EndsWith(System.IO.Path.DirectorySeparatorChar + find));
        }
        public IEnumerable<CompilerReference> GetReferences(TypeContext context, IEnumerable<CompilerReference> includeAssemblies)
        {

            #region 加载依赖程序集  此处是加载所有程序集，效率需要改进

            return compilerReference;
            #endregion
        }
    }

　　

　　　CompileViewAndLayout()是编译视图文件的主要部分，其中有路径的转换、key的定义规则等。

　　　　获取视图文件对应编译后的缓存key：Engine.Razor.GetKey()；

　　　   编译模板文件（即layout部分）：Engine.Razor.AddTemplate();

　　　　编译视图文件：Engine.Razor.RunCompile()。

转载请注明出处：http://www.cnblogs.com/eric-z/p/5102718.html