NOP源码分析十二

接上一节

/// <summary>
        /// Perform file deply
        /// </summary>
        /// <param name="plug">Plugin file info</param>
        /// <returns>Assembly</returns>
        private static Assembly PerformFileDeploy(FileInfo plug)
        {
            if (plug.Directory.Parent == null)
                throw new InvalidOperationException("The plugin directory for the " + plug.Name +
                                                    " file exists in a folder outside of the allowed nopCommerce folder heirarchy");

            FileInfo shadowCopiedPlug;

            if (CommonHelper.GetTrustLevel() != AspNetHostingPermissionLevel.Unrestricted)
            {
                //all plugins will need to be copied to ~/Plugins/bin/
                //this is aboslutely required because all of this relies on probingPaths being set statically in the web.config
                
                //were running in med trust, so copy to custom bin folder
                var shadowCopyPlugFolder = Directory.CreateDirectory(_shadowCopyFolder.FullName);
                shadowCopiedPlug = InitializeMediumTrust(plug, shadowCopyPlugFolder);
            }
            else
            {
                var directory = AppDomain.CurrentDomain.DynamicDirectory;
                Debug.WriteLine(plug.FullName + " to " + directory);
                //were running in full trust so copy to standard dynamic folder
                shadowCopiedPlug = InitializeFullTrust(plug, new DirectoryInfo(directory));
            }

            //we can now register the plugin definition
            var shadowCopiedAssembly = Assembly.Load(AssemblyName.GetAssemblyName(shadowCopiedPlug.FullName));

            //add the reference to the build manager
            Debug.WriteLine("Adding to BuildManager: '{0}'", shadowCopiedAssembly.FullName);
            BuildManager.AddReferencedAssembly(shadowCopiedAssembly);

            return shadowCopiedAssembly;
        }

查看CommonHelper.GetTrustLevel方法：

/// <summary>
        /// Finds the trust level of the running application (http://blogs.msdn.com/dmitryr/archive/2007/01/23/finding-out-the-current-trust-level-in-asp-net.aspx)
        /// </summary>
        /// <returns>The current trust level.</returns>
        public static AspNetHostingPermissionLevel GetTrustLevel()
        {
            if (!_trustLevel.HasValue)
            {
                //set minimum
                _trustLevel = AspNetHostingPermissionLevel.None;

                //determine maximum
                foreach (AspNetHostingPermissionLevel trustLevel in new[] {
                                AspNetHostingPermissionLevel.Unrestricted,
                                AspNetHostingPermissionLevel.High,
                                AspNetHostingPermissionLevel.Medium,
                                AspNetHostingPermissionLevel.Low,
                                AspNetHostingPermissionLevel.Minimal 
                            })
                {
                    try
                    {
                        new AspNetHostingPermission(trustLevel).Demand();
                        _trustLevel = trustLevel;
                        break; //we've set the highest permission we can
                    }
                    catch (System.Security.SecurityException)
                    {
                        continue;
                    }
                }
            }
            return _trustLevel.Value;
        }

大体意思是：如果新人级别没有值，则先设置为不授予任何权限，然后遍历权限，从最大权限开始，如果授予权限成功 就返回，如果报错继续授予下一个权限，就是授予当前能授予的最大权限。

如果不是最大权限的话，创建BIN目录，并调用方法：

var shadowCopyPlugFolder = Directory.CreateDirectory(_shadowCopyFolder.FullName);
                shadowCopiedPlug = InitializeMediumTrust(plug, shadowCopyPlugFolder);

InitializeMediumTrust方法如下：

// <summary>
        /// Used to initialize plugins when running in Medium Trust
        /// </summary>
        /// <param name="plug"></param>
        /// <param name="shadowCopyPlugFolder"></param>
        /// <returns></returns>
        private static FileInfo InitializeMediumTrust(FileInfo plug, DirectoryInfo shadowCopyPlugFolder)
        {
            var shouldCopy = true;
            var shadowCopiedPlug = new FileInfo(Path.Combine(shadowCopyPlugFolder.FullName, plug.Name));

            //check if a shadow copied file already exists and if it does, check if it's updated, if not don't copy
            if (shadowCopiedPlug.Exists)
            {
                //it's better to use LastWriteTimeUTC, but not all file systems have this property
                //maybe it is better to compare file hash?
                var areFilesIdentical = shadowCopiedPlug.CreationTimeUtc.Ticks >= plug.CreationTimeUtc.Ticks;
                if (areFilesIdentical)
                {
                    Debug.WriteLine("Not copying; files appear identical: '{0}'", shadowCopiedPlug.Name);
                    shouldCopy = false;
                }
                else
                {
                    //delete an existing file

                    //More info: http://www.nopcommerce.com/boards/t/11511/access-error-nopplugindiscountrulesbillingcountrydll.aspx?p=4#60838
                    Debug.WriteLine("New plugin found; Deleting the old file: '{0}'", shadowCopiedPlug.Name);
                    File.Delete(shadowCopiedPlug.FullName);
                }
            }

            if (shouldCopy)
            {
                try
                {
                    File.Copy(plug.FullName, shadowCopiedPlug.FullName, true);
                }
                catch (IOException)
                {
                    Debug.WriteLine(shadowCopiedPlug.FullName + " is locked, attempting to rename");
                    //this occurs when the files are locked,
                    //for some reason devenv locks plugin files some times and for another crazy reason you are allowed to rename them
                    //which releases the lock, so that it what we are doing here, once it's renamed, we can re-shadow copy
                    try
                    {
                        var oldFile = shadowCopiedPlug.FullName + Guid.NewGuid().ToString("N") + ".old";
                        File.Move(shadowCopiedPlug.FullName, oldFile);
                    }
                    catch (IOException exc)
                    {
                        throw new IOException(shadowCopiedPlug.FullName + " rename failed, cannot initialize plugin", exc);
                    }
                    //ok, we've made it this far, now retry the shadow copy
                    File.Copy(plug.FullName, shadowCopiedPlug.FullName, true);
                }
            }

            return shadowCopiedPlug;
        }

根据传入值获得 bin目录的 new  fileinfo,如果此文件已经存在，则比较创建的UTC时间。

如果是旧文件就删除，如果是新文件 就设置 需要拷贝为false.

如果需要拷贝为true,则进行拷贝到BIN。。。  最后返回BIN的全路径文件名。

最后根据这个文件名加载程序集，并返回这个程序集。

用foreach循环加载剩余的DLL。

最后设置PluginType类型的值 并添加到referencedPlugins。 最后赋值

ReferencedPlugins = referencedPlugins;
                IncompatiblePlugins = incompatiblePlugins;

PluginManager类的init方法就是设置ReferencedPlugins 。

EnsurePluginsAreLoaded方法内将它（ReferencedPlugins .tolist）赋值给_plugins。

GetPluginDescriptors 方法：

/// <summary>
        /// Get plugin descriptors
        /// </summary>
        /// <param name="loadMode">Load plugins mode</param>
        /// <param name="storeId">Load records allowed only in a specified store; pass 0 to load all records</param>
        /// <param name="group">Filter by plugin group; pass null to load all records</param>
        /// <returns>Plugin descriptors</returns>
        public virtual IEnumerable<PluginDescriptor> GetPluginDescriptors(LoadPluginsMode loadMode = LoadPluginsMode.InstalledOnly,
            int storeId = 0, string group = null)
        {
            //ensure plugins are loaded
            EnsurePluginsAreLoaded();

            return _plugins.Where(p => CheckLoadMode(p, loadMode) && AuthenticateStore(p, storeId) && CheckGroup(p, group));
        }

最后一句，帅选出 已安装的，并且在storeID内的。group为空也肯定为true 的plugins.