【Visual Studio】在VS2012中使用VSXtra

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(, moniker, IntPtr.Zero) == )
            {
                string displayName;
                moniker[].GetDisplayName(ctx, moniker[], out displayName);
                if (displayName == ideMoniker)
                {
                    // --- Got the IDE Automation Object
                    Object oDTE;
                    rot.GetObject(moniker[], 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;
            }
        }

附：修改后的VSXtra