【Visual Studio】在VS2012中使用VSXtra

最近工作中需要把之前為VS 2010寫的擴展遷移到VS 2012上。在將工程版本改為VS2012之后，代碼沒有修改，直接編譯通過，也可以安裝到VS2012上。

不過，在實際使用的時候，卻報錯，提示“The framework has not been sited!”。調試后發現，這個錯誤是我們在IDE開發中用到的VSXtra報出的。錯誤的報錯位置是在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;
        }

從代碼可以看到，異常拋出的條件是在GlobalServiceProvider不存在的時候。那么這個HasGlobalServiceProvider屬性是什么樣的呢：

        // --------------------------------------------------------------------------------------------
        /// <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); }
        }

看來是判斷GlobalServiceProvider是否為null。那么，是誰負責設置這個GlobalServiceProvider的呢？我們通過Find All References可以發現這個屬性是在SuggestGlobalServiceProvider方法中被設置的，這個方法有多個重載，跟蹤一下，需要調用到的是這個：

        // --------------------------------------------------------------------------------------------
        /// <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);
        }

而這個SuggestGlobalServiceProvider則是在一個叫做TryToGetServiceProviderFromCurrentProcess的關鍵方法中被調用到的（部分代碼省略）：

        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);
        }

其大概意思是從當前進程中獲取一些信息，跟通過傳入的vsMoniker格式化之后的一個字符串進行比對，如果名字是一樣的，則通過它獲取VS IDE的DTE實例。那么，這個vsMoniker是個什么東東？又是誰調用了這個方法呢？

    // --------------------------------------------------------------------------------------------
    /// <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;
      }
    }

看到這兒，我們也明白了，敢情VSXtra這兒寫死了幾個字符串{ "!VisualStudio.DTE.9.0:{0}", "!VisualStudio.DTE.10.0:{0}" }，跟VS版本相關，而VS2012的版本號是11，這里沒有，所以當然找不到DTE Instance了。

最簡單的修改版本，添加一個VS2012的版本號："!VisualStudio.DTE.11.0:{0}"，運行測試OK。

不過，對於這種hard-code的寫法筆者是看着很不爽，那么，有沒動態獲取已經安裝的VS版本的方法呢？答案是：有，通過注冊表。

於是最后的代碼修改如下：

        // --------------------------------------------------------------------------------------------
        /// <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