MVC插件实现-白红宇

MVC插件实现

阅读量：6948 次

发布时间：2019-06-27

本文共 20790 字，大约阅读时间需要 69 分钟。

本人第一篇随笔，在园子里逛了这么久，今天也记录一篇自己的劳动成果，也是给自己以后留个记录。

最近领导让我搞一下插件化，就是实现多个web工程通过配置文件进行组装。之前由于做过一个简单的算是有点经验，当时使用的不是area，后来通过翻看orchard源码有点启发，打算使用area改一下。

实现插件化，需要解决四个问题：

1、如何发现插件以及加载插件及其所依赖的dll

2、如何注册路由，正确调用插件的Controller和Action

3、如何实现ViewEngine，正确的发现View

4、页面中的Url如何自动生成

以下下我们带着这四个问题依次分析解决：

1、如何发现插件以及加载插件及其所依赖的dll

该问题我完全使用了Nop插件的实现方式，为每个工程定义一个Plugin.txt配置文件，运行时通过注册[assembly: PreApplicationStartMethod(typeof(PluginManager), "Initialize")]这个方法，在Application_Start（）之前发现和加载插件。PluginManager负责管理加载插件，通过解析Plugin.txt,识别插件的dll和它所依赖的dll。通过Assembly.Load()方法加载dll并使用BuildManager.AddReferencedAssembly(shadowCopiedAssembly)为web项目动态添加引用。由于web项目存在不同的信任级别，在FullTrust级别可以将这些dll直接拷贝到AppDomain.CurrentDomain.DynamicDirectory文件夹下面。但是在其他信任级别下无法访问该目录，Nop通过复制到一个临时目录并在web.config中修改 <probingprivatePath="Plugins/bin/" />的值来让iis自动探索该目录。

代码如下：

using System;using System.Collections.Generic;using System.IO;using System.Linq;using System.Reflection;using System.Text;using System.Threading.Tasks;namespace Framework.Core.Plugins{   public class Plugin    {        ///         /// 插件名称，唯一标识        /// 
        public string PluginName { get; set; }        ///         /// 插件显示名称        /// 
        public virtual string PluginFriendlyName { get; set; }        ///         /// 插件主文件（DLL）名称        /// 
        public string PluginFileName { get; set; }        ///         /// 插件控制器命名空间        /// 
        public string ControllerNamespace { get; set; }        ///         /// 插件主文件文件信息        /// 
        public virtual FileInfo PluginFileInfo { get; internal set; }        ///         /// 插件程序集        /// 
        public virtual Assembly ReferencedAssembly { get; internal set; }        ///         /// 描述        /// 
        public virtual string Description { get; set; }        ///         /// 显示顺序        /// 
        public virtual int DisplayOrder { get; set; }        ///         /// 是否已安装        /// 
        public virtual bool Installed { get; set; }    }}

View Code

using System;using System.Collections.Generic;using System.Configuration;using System.Diagnostics;using System.IO;using System.Linq;using System.Reflection;using System.Threading;using System.Web;using System.Web.Compilation;using Framework.Core.Plugins;using Framework.Core.Infrastructure;[assembly: PreApplicationStartMethod(typeof(PluginManager), "Initialize")]namespace Framework.Core.Plugins{    public class PluginManager    {        #region Const        private const string InstalledPluginsFilePath = "~/App_Data/InstalledPlugins.txt";        private const string PluginsPath = "~/Plugins";        private const string ShadowCopyPath = "~/Plugins/bin";        #endregion        #region Fields        private static readonly ReaderWriterLockSlim Locker = new ReaderWriterLockSlim();        private static DirectoryInfo _shadowCopyFolder;        private static bool _clearShadowDirectoryOnStartup;        #endregion        #region Methods        public static IEnumerable
      
        ReferencedPlugins { get; set; }        /// 
               /// 初始化插件        /// 
        public static void Initialize()        {            using (new WriteLockDisposable(Locker))            {                var pluginFolder = new DirectoryInfo(CommonHelper.MapPath(PluginsPath));                _shadowCopyFolder = new DirectoryInfo(CommonHelper.MapPath(ShadowCopyPath));                var referencedPlugins = new List
       
        ();                              _clearShadowDirectoryOnStartup = !String.IsNullOrEmpty(ConfigurationManager.AppSettings["ClearPluginsShadowDirectoryOnStartup"]) &&                   Convert.ToBoolean(ConfigurationManager.AppSettings["ClearPluginsShadowDirectoryOnStartup"]);                try                {                    //获取已经加载的插件名称                    var installedPluginNames = PluginFileParser.ParseInstalledPluginsFile(GetInstalledPluginsFilePath());                    Debug.WriteLine("创建临时目录");                    Directory.CreateDirectory(pluginFolder.FullName);                    Directory.CreateDirectory(_shadowCopyFolder.FullName);                    //获取临时目录中的dll文件                    var binFiles = _shadowCopyFolder.GetFiles("*", SearchOption.AllDirectories);                    if (_clearShadowDirectoryOnStartup)                    {                        //清除临时目录中的数据                        foreach (var f in binFiles)                        {                            Debug.WriteLine("删除文件： " + f.Name);                            try                            {                                File.Delete(f.FullName);                            }                            catch (Exception exc)                            {                                Debug.WriteLine("删除文件异常： " + f.Name + ".  异常信息: " + exc);                            }                        }                    }                    //加载插件                    foreach (var dfd in GetPluginFilesAndPlugins(pluginFolder))                    {                        var pluginFile = dfd.Key;                        var plugin = dfd.Value;                        //验证插件名称                        if (String.IsNullOrWhiteSpace(plugin.PluginName))                            throw new Exception(string.Format("插件：'{0}' 没有设置名称. 请设置唯一的PluginName，重新编译.", pluginFile.FullName));                        if (referencedPlugins.Contains(plugin))                            throw new Exception(string.Format("插件名称：'{0}' 已经被占用，请重新设置唯一的PluginName，重新编译", plugin.PluginName));                        //设置是否已经安装                        plugin.Installed = installedPluginNames                            .FirstOrDefault(x => x.Equals(plugin.PluginName, StringComparison.InvariantCultureIgnoreCase)) != null;                        try                        {                            if (pluginFile.Directory == null)                                throw new Exception(string.Format("'{0}'插件目录无效，无法解析插件dll文件", pluginFile.Name));                            //获取插件中的所有DLL                            var pluginDLLs = pluginFile.Directory.GetFiles("*.dll", SearchOption.AllDirectories)                                //just make sure we're not registering shadow copied plugins                                .Where(x => !binFiles.Select(q => q.FullName).Contains(x.FullName))                                .Where(x => IsPackagePluginFolder(x.Directory))                                .ToList();                            //获取主插件文件                            var mainPluginDLL = pluginDLLs                                .FirstOrDefault(x => x.Name.Equals(plugin.PluginFileName, StringComparison.InvariantCultureIgnoreCase));                            plugin.PluginFileInfo = mainPluginDLL;                            //复制主文件到临时目录，并加载主文件                            plugin.ReferencedAssembly = PerformFileDeploy(mainPluginDLL);                            //加载其他插件相关dll                            foreach (var dll in pluginDLLs                                .Where(x => !x.Name.Equals(mainPluginDLL.Name, StringComparison.InvariantCultureIgnoreCase))                                .Where(x => !IsAlreadyLoaded(x)))                                    PerformFileDeploy(dll);                            referencedPlugins.Add(plugin);                        }                        catch (ReflectionTypeLoadException ex)                        {                            var msg = string.Format("Plugin '{0}'. ", plugin.PluginFriendlyName);                            foreach (var e in ex.LoaderExceptions)                                msg += e.Message + Environment.NewLine;                            var fail = new Exception(msg, ex);                            throw fail;                        }                        catch (Exception ex)                        {                            var msg = string.Format("Plugin '{0}'. {1}", plugin.PluginFriendlyName, ex.Message);                            var fail = new Exception(msg, ex);                            throw fail;                        }                    }                }                catch (Exception ex)                {                    var msg = string.Empty;                    for (var e = ex; e != null; e = e.InnerException)                        msg += e.Message + Environment.NewLine;                    var fail = new Exception(msg, ex);                    throw fail;                }                ReferencedPlugins = referencedPlugins;            }        }        /// 
                /// 安装插件        /// 
        /// 
        插件名称        public static void MarkPluginAsInstalled(string pluginName)        {            if (String.IsNullOrEmpty(pluginName))                throw new ArgumentNullException("pluginName");            var filePath = CommonHelper.MapPath(InstalledPluginsFilePath);            if (!File.Exists(filePath))                using (File.Create(filePath))                {                                  }            var installedPluginSystemNames = PluginFileParser.ParseInstalledPluginsFile(GetInstalledPluginsFilePath());            bool alreadyMarkedAsInstalled = installedPluginSystemNames                                .FirstOrDefault(x => x.Equals(pluginName, StringComparison.InvariantCultureIgnoreCase)) != null;            if (!alreadyMarkedAsInstalled)                installedPluginSystemNames.Add(pluginName);            PluginFileParser.SaveInstalledPluginsFile(installedPluginSystemNames,filePath);        }        /// 
                /// 卸载插件        /// 
        /// 
        插件名称        public static void MarkPluginAsUninstalled(string pluginName)        {            if (String.IsNullOrEmpty(pluginName))                throw new ArgumentNullException("pluginName");            var filePath = CommonHelper.MapPath(InstalledPluginsFilePath);            if (!File.Exists(filePath))                using (File.Create(filePath))                {                                   }            var installedPluginSystemNames = PluginFileParser.ParseInstalledPluginsFile(GetInstalledPluginsFilePath());            bool alreadyMarkedAsInstalled = installedPluginSystemNames                                .FirstOrDefault(x => x.Equals(pluginName, StringComparison.InvariantCultureIgnoreCase)) != null;            if (alreadyMarkedAsInstalled)                installedPluginSystemNames.Remove(pluginName);            PluginFileParser.SaveInstalledPluginsFile(installedPluginSystemNames,filePath);        }        /// 
                /// 卸载所有插件        /// 
        public static void MarkAllPluginsAsUninstalled()        {            var filePath = CommonHelper.MapPath(InstalledPluginsFilePath);            if (File.Exists(filePath))                File.Delete(filePath);        }        #endregion        #region 工具        /// 
                ///获取指定目录下的所有插件文件（Plugin.text）和插件信息（Plugin)        /// 
        /// 
        Plugin目录        /// 
        
         插件文件和插件
                private static IEnumerable
        
         
          > GetPluginFilesAndPlugins(DirectoryInfo pluginFolder)        {            if (pluginFolder == null)                throw new ArgumentNullException("pluginFolder");            var result = new List
          
           
            >(); //add display order and path to list foreach (var descriptionFile in pluginFolder.GetFiles("Plugin.txt", SearchOption.AllDirectories)) { if (!IsPackagePluginFolder(descriptionFile.Directory)) continue; //解析插件配置文件 var plugin = PluginFileParser.ParsePluginFile(descriptionFile.FullName); result.Add(new KeyValuePair
            
             (descriptionFile, plugin)); } //插件排序，数字越低排名越高 result.Sort((firstPair, nextPair) => firstPair.Value.DisplayOrder.CompareTo(nextPair.Value.DisplayOrder)); return result; } /// 
              /// 判断程序集是否已经加载 /// 
 /// 
             程序集文件 /// 
             
              Result
              private static bool IsAlreadyLoaded(FileInfo fileInfo) { try { string fileNameWithoutExt = Path.GetFileNameWithoutExtension(fileInfo.FullName); if (fileNameWithoutExt == null) throw new Exception(string.Format("无法获取文件名：{0}", fileInfo.Name)); foreach (var a in AppDomain.CurrentDomain.GetAssemblies()) { string assemblyName = a.FullName.Split(new[] { ',' }).FirstOrDefault(); if (fileNameWithoutExt.Equals(assemblyName, StringComparison.InvariantCultureIgnoreCase)) return true; } } catch (Exception exc) { Debug.WriteLine("无法判断程序集是否加载。" + exc); } return false; } /// 
              ///执行解析文件 /// 
 /// 
             插件文件 /// 
             
              Assembly
              private static Assembly PerformFileDeploy(FileInfo plug) { if (plug.Directory.Parent == null) throw new InvalidOperationException("插件" + plug.Name + ":目录无效" ); FileInfo shadowCopiedPlug; if (CommonHelper.GetTrustLevel() != AspNetHostingPermissionLevel.Unrestricted) { //运行在MediumTrust下（在MediumTrust下无法访问DynamicDirectory，也无法设置ResolveAssembly event） //需要将所有插件dll都需要拷贝到~/Plugins/bin/下的临时目录，因为web.config中的probingPaths设置的是该目录 var shadowCopyPlugFolder = Directory.CreateDirectory(_shadowCopyFolder.FullName); shadowCopiedPlug = InitializeMediumTrust(plug, shadowCopyPlugFolder); } else { //运行在FullTrust下，可以直接使用标准的DynamicDirectory文件夹，作为临时目录 var directory = AppDomain.CurrentDomain.DynamicDirectory; Debug.WriteLine(plug.FullName + " to " + directory); shadowCopiedPlug = InitializeFullTrust(plug, new DirectoryInfo(directory)); } //加载程序集 var shadowCopiedAssembly = Assembly.Load(AssemblyName.GetAssemblyName(shadowCopiedPlug.FullName)); //添加引用信息到BuildManager Debug.WriteLine("添加到BuildManager: '{0}'", shadowCopiedAssembly.FullName); BuildManager.AddReferencedAssembly(shadowCopiedAssembly); return shadowCopiedAssembly; } /// 
              /// FullTrust级别下的插件初始化 /// 
 /// 
              /// 
              /// 
              private static FileInfo InitializeFullTrust(FileInfo plug, DirectoryInfo shadowCopyPlugFolder) { var shadowCopiedPlug = new FileInfo(Path.Combine(shadowCopyPlugFolder.FullName, plug.Name)); try { File.Copy(plug.FullName, shadowCopiedPlug.FullName, true); } catch (IOException) { Debug.WriteLine(shadowCopiedPlug.FullName + " 文件已被锁, 尝试重命名"); //可能被 devenv锁住，可以通过重命名来解锁 try { var oldFile = shadowCopiedPlug.FullName + Guid.NewGuid().ToString("N") + ".old"; File.Move(shadowCopiedPlug.FullName, oldFile); } catch (IOException exc) { throw new IOException(shadowCopiedPlug.FullName + " 重命名失败, 无法初始化插件", exc); } //重新尝试复制 File.Copy(plug.FullName, shadowCopiedPlug.FullName, true); } return shadowCopiedPlug; } /// 
              /// MediumTrust级别下的插件初始化 /// 
 /// 
              /// 
              /// 
              private static FileInfo InitializeMediumTrust(FileInfo plug, DirectoryInfo shadowCopyPlugFolder) { var shouldCopy = true; var shadowCopiedPlug = new FileInfo(Path.Combine(shadowCopyPlugFolder.FullName, plug.Name)); //检查插件是否存在，如果存在，判断是否需要更新 if (shadowCopiedPlug.Exists) { var areFilesIdentical = shadowCopiedPlug.CreationTimeUtc.Ticks >= plug.CreationTimeUtc.Ticks; if (areFilesIdentical) { Debug.WriteLine("插件已经存在，不需要更新: '{0}'", shadowCopiedPlug.Name); shouldCopy = false; } else { //删除现有插件 Debug.WriteLine("有新插件; 删除现有插件: '{0}'", shadowCopiedPlug.Name); File.Delete(shadowCopiedPlug.FullName); } } if (shouldCopy) { try { File.Copy(plug.FullName, shadowCopiedPlug.FullName, true); } catch (IOException) { Debug.WriteLine(shadowCopiedPlug.FullName + " 文件已被锁, 尝试重命名"); //可能被 devenv锁住，可以通过重命名来解锁 try { var oldFile = shadowCopiedPlug.FullName + Guid.NewGuid().ToString("N") + ".old"; File.Move(shadowCopiedPlug.FullName, oldFile); } catch (IOException exc) { throw new IOException(shadowCopiedPlug.FullName + " 重命名失败, 无法初始化插件", exc); } //重新尝试复制 File.Copy(plug.FullName, shadowCopiedPlug.FullName, true); } } return shadowCopiedPlug; } /// 
              ///判断文件是否属于插件目录下的文件（Plugins下） /// 
 /// 
              /// 
              private static bool IsPackagePluginFolder(DirectoryInfo folder) { if (folder == null) return false; if (folder.Parent == null) return false; if (!folder.Parent.Name.Equals("Plugins", StringComparison.InvariantCultureIgnoreCase)) return false; return true; } /// 
              /// 获取InstalledPlugins.txt文件的物理路径 /// 
 /// 
              private static string GetInstalledPluginsFilePath() { return CommonHelper.MapPath(InstalledPluginsFilePath); } #endregion }}

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2、如何注册路由，正确调用插件的Controller和Action

路由我通过扩展现Mvc的RouteCollection的MapRoute方法，将插件名称作为area强行插入到DataToken中，这样在ViewEngine中可以使用area规则来发现视图。然后重写RegisterRoutes方法，通过遍历所有插件集合，添加指定的路由，并将所有插件的Controller的命名空间写入到插件匹配模式中，这样可以解决不同插件之间Controller重名的问题。

public static Route MapRoute(this RouteCollection routes, string name, string url, object defaults, object constraints, string[] namespaces,string area)        {            if (routes == null)            {                throw new ArgumentNullException("routes");            }            if (url == null)            {                throw new ArgumentNullException("url");            }            Route route = new Route(url, new MvcRouteHandler())            {                Defaults = new RouteValueDictionary(defaults),                Constraints = new RouteValueDictionary(constraints),                DataTokens = new RouteValueDictionary()            };            if ((namespaces != null) && (namespaces.Length > 0))            {                route.DataTokens["Namespaces"] = namespaces;            }            if (!string.IsNullOrEmpty(area))            {                route.DataTokens["area"] = area;            }            routes.Add(name, route);            return route;        }

View Code

public static void RegisterPluginRoutes(RouteCollection routes)        {            routes.IgnoreRoute("{resource}.axd/{*pathInfo}");            foreach (var plugin in PluginManager.ReferencedPlugins)            {                    routes.MapRoute(plugin.PluginName,                    string.Concat(plugin.PluginName, "/{controller}/{action}/{id}"),                    new { area= plugin.PluginName, controller = "Home", action = "Index", id = UrlParameter.Optional },                   new string[]{ plugin.ControllerNamespace}, plugin.PluginName);            }            routes.MapRoute(                 name: "Default",                 url: "{controller}/{action}/{id}",                 defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional },                 namespaces:new string[] { "GWT.Framework.Web.Controllers" }              );            }

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3、如何实现ViewEngine，正确的发现View

关于这个问题我发现Nop和Orchard中好多地方都是硬编码，通过VIEW（~/Plugin/XXX/views/XXX/XX.csthml）的方式来发现视图。不知他们是何用意，我觉这样耦合度过高。此处我通过前面路由中插入的area并配合实现一个继承自RazorViewEngine的视图引擎，将所有的插件请求定位到~/Plugins/{area}/Views/{controller}/{action}.cshtml。同时替换掉原有的视图引擎。代码如下：

public class PluginViewEngine : RazorViewEngine    {        public PluginViewEngine()        {            AreaViewLocationFormats = new[] {                "~/Areas/{2}/Views/{1}/{0}.cshtml",                "~/Areas/{2}/Views/Shared/{0}.cshtml",                "~/Plugins/{2}/Views/{1}/{0}.cshtml",                "~/Plugins/{2}/Views/Shared/{0}.cshtml"            };            AreaMasterLocationFormats = new[] {                "~/Areas/{2}/Views/{1}/{0}.cshtml",                "~/Areas/{2}/Views/Shared/{0}.cshtml",                 "~/Plugins/{2}/Views/{1}/{0}.cshtml",                "~/Plugins/{2}/Views/Shared/{0}.cshtml"            };            AreaPartialViewLocationFormats = new[] {                "~/Areas/{2}/Views/{1}/{0}.cshtml",                "~/Areas/{2}/Views/Shared/{0}.cshtml",                "~/Plugins/{2}/Views/{1}/{0}.cshtml",                "~/Plugins/{2}/Views/Shared/{0}.cshtml"            };            FileExtensions = new[] { "cshtml" };        }    }

View Code

protected void Application_Start()        {            ViewEngines.Engines.Clear();            ViewEngines.Engines.Add(new PluginViewEngine());            AreaRegistration.RegisterAllAreas();            FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);            ApplicationStartup.RegisterPluginRoutes(RouteTable.Routes);            BundleConfig.RegisterBundles(BundleTable.Bundles);        }

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4、页面中的Url如何自动生成

我们知道页面中的url可以使用硬编码方式比如/Home/Index,也可以使用Html.ActionLink（“Index”，“Home”）或者Url.Action方式实现。前者硬编码的方式已经不适用于插件化，因为开发者不知道是否会被用作插件，如果强行写入/Pluin1/Home/Index，势必导致本地无法运行。在插件系统中应该使用后两者，因为他们都是用过路由系统输出URL的。MVC框架会基于当前的Controller到路由系统中找到匹配的路径返回给前台页面。

对于URL我们可以使用Html和Url帮助器生成，但是对于Script和css等内容文件MVC框架就无能为力了。为了解决内容文件的加载，我扩展了UrlHelper帮助器，根据当前的请求中是否有area来生成相对路径。代码如下

public static string PluginContent(this UrlHelper urlHelper, string url)        {            if (urlHelper.RequestContext.RouteData.Values.Keys.Contains("area"))            {                var area = urlHelper.RequestContext.RouteData.Values["area"].ToString();                if (!string.IsNullOrEmpty(area))                {                    url = url.Substring(url.IndexOf("/") + 1);                    return string.Format("~/Plugins/{0}/{1}", area, url);                }            }            return url;        }

View Code

在页面中可以如下调用： @Url.PluginContent("/Views/Shared/_Layout.cshtml")

参考文档：

https://shazwazza.com/post/Developing-a-plugin-framework-in-ASPNET-with-medium-trust.aspx

http://www.cnblogs.com/longyunshiye/p/5786446.html

转载于:https://www.cnblogs.com/pippenxu/p/6606621.html

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