最近工作中需要把之前为VS 2010写的扩展迁移到VS 2012上。在将工程版本改为VS2012之后，代码没有修改，直接编译通过，也可以安装到VS2012上。
不过，在实际使用的时候，却报错，提示“The framework has not been sited!”。调试后发现，这个错误是我们在IDE开发中用到的VSXtra报出的。错误的报错位置是在SiteManager的GetGlobalService方法中：
// -------------------------------------------------------------------------------------------- /// <summary> /// Gets a global service with the specified address and behavior type. /// </summary> /// <typeparam name="SInterface">Address type of the service</typeparam> /// <typeparam name="TInterface">Behavior (endpoint) type of the service</typeparam> /// <returns>The service instance obtained.</returns> // -------------------------------------------------------------------------------------------- public static TInterface GetGlobalService<SInterface, TInterface>() where TInterface : class where SInterface : class { if (!HasGlobalServiceProvider) throw new InvalidOperationException("The framework has not been sited!"); var ti = GlobalServiceProvider.GetService<SInterface, TInterface>(); if (ti == null) throw new NotSupportedException(typeof(SInterface).FullName); return ti; }
从代码可以看到，异常抛出的条件是在GlobalServiceProvider不存在的时候。那么这个HasGlobalServiceProvider属性是什么样的呢：
// -------------------------------------------------------------------------------------------- /// <summary> /// Gets the flag indicating if the SiteManager has already a global service provider or not. /// </summary> // -------------------------------------------------------------------------------------------- public static bool HasGlobalServiceProvider { get { return (GlobalServiceProvider != null); } }
看来是判断GlobalServiceProvider是否为null。那么，是谁负责设置这个GlobalServiceProvider的呢？我们通过Find All References可以发现这个属性是在SuggestGlobalServiceProvider方法中被设置的，这个方法有多个重载，跟踪一下，需要调用到的是这个：
// -------------------------------------------------------------------------------------------- /// <summary> /// Suggests a DTE2 object as the global service provider for SiteManager. /// </summary> /// <param name="dte2">DTE2 object as a global service provider candidate.</param> // -------------------------------------------------------------------------------------------- public static void SuggestGlobalServiceProvider(DTE2 dte2) { SuggestGlobalServiceProvider(dte2 as IOleServiceProvider); }
而这个SuggestGlobalServiceProvider则是在一个叫做TryToGetServiceProviderFromCurrentProcess的关键方法中被调用到的（部分代码省略）：
private static void TryToGetServiceProviderFromCurrentProcess(string vsMoniker) { ...... string ideMoniker = String.Format(vsMoniker, Process.GetCurrentProcess().Id); ...... while (enumMoniker.Next(1, moniker, IntPtr.Zero) == 0) { string displayName; moniker[0].GetDisplayName(ctx, moniker[0], out displayName); if (displayName == ideMoniker) { // --- Got the IDE Automation Object Object oDTE; rot.GetObject(moniker[0], out oDTE); dte = oDTE as DTE2; if (dte != null) break; } } SuggestGlobalServiceProvider(dte); }
其大概意思是从当前进程中获取一些信息，跟通过传入的vsMoniker格式化之后的一个字符串进行比对，如果名字是一样的，则通过它获取VS IDE的DTE实例。那么，这个vsMoniker是个什么东东？又是谁调用了这个方法呢？
// -------------------------------------------------------------------------------------------- /// <summary> /// Monikers of possible DTE objects. Right now VS 2008 and VS 2010 is handled. /// </summary> // -------------------------------------------------------------------------------------------- private static readonly List<string> VSMonikers = new List<string> { "!VisualStudio.DTE.9.0:{0}", "!VisualStudio.DTE.10.0:{0}" }; // -------------------------------------------------------------------------------------------- /// <summary> /// The static constructor automatically tries to assign the SiteManager static class to a site /// that accesses VS IDE global services. /// </summary> // -------------------------------------------------------------------------------------------- static SiteManager() { foreach (string moniker in VSMonikers) { TryToGetServiceProviderFromCurrentProcess(moniker); if (HasGlobalServiceProvider) return; } }
看到这儿，我们也明白了，敢情VSXtra这儿写死了几个字符串{ "!VisualStudio.DTE.9.0:{0}", "!VisualStudio.DTE.10.0:{0}" }，跟VS版本相关，而VS2012的版本号是11，这里没有，所以当然找不到DTE Instance了。
最简单的修改版本，添加一个VS2012的版本号："!VisualStudio.DTE.11.0:{0}"，运行测试OK。
不过，对于这种hard-code的写法笔者是看着很不爽，那么，有没动态获取已经安装的VS版本的方法呢？答案是：有，通过注册表。
于是最后的代码修改如下：
// -------------------------------------------------------------------------------------------- /// <summary> /// Monikers of possible DTE objects. Right now VS 2008 and VS 2010 is handled. /// </summary> // -------------------------------------------------------------------------------------------- private static readonly IEnumerable<string> VSMonikers; // -------------------------------------------------------------------------------------------- /// <summary> /// The static constructor automatically tries to assign the SiteManager static class to a site /// that accesses VS IDE global services. /// </summary> // -------------------------------------------------------------------------------------------- static SiteManager() { var vsRegKey = Registry.CurrentUser .OpenSubKey("Software") .OpenSubKey("Microsoft") .OpenSubKey("VisualStudio"); var installedNames = vsRegKey.GetSubKeyNames().Where(x => !x.Contains("Exp") && !x.Contains("_Config")); VSMonikers = installedNames.Select(x => "!VisualStudio.DTE." + x + ":{0}").ToArray(); foreach (string moniker in VSMonikers) { TryToGetServiceProviderFromCurrentProcess(moniker); if (HasGlobalServiceProvider) return; } }