插件 DLL 的本地化资源的 c# 路径

Question

在我的 C# 应用程序中，我有一个插件机制，可以从配置 XML 文件中指定的不同路径加载插件 DLL。我的应用程序是可本地化的。主程序集(*.exe)以标准 .NET 方式在 exe 旁边有本地化语言的附属程序集(例如 .\en\en-US\main.resources.dll; .\de\de_DE\main.resources.dll; 等)。

我开始对一个插件进行本地化，结果发现附属程序集必须放在 exe 旁边的文件夹中。当把它放在插件 DLL 旁边时，资源管理器找不到它。

但是，由于我的插件是可互换的并且可能位于不同的文件夹中，所以我非常希望将本地化资源程序集放在插件旁边，不要放在 exe 中。

这可能吗？!？!

我可以接受的另一种选择是将本地化资源嵌入到 DLL 中。这可能吗？？

干杯， 菲利克斯

Answer 1

我在为我们公司开发产品时遇到了这个问题。我没有在任何地方找到答案，所以我会在这里发布我的解决方案，以防其他人发现自己处于同样的情况。

从 .NET 4.0 开始，这个问题有了解决方案，因为附属程序集现在被传递到 AssemblyResolve 处理程序。如果您已经有一个可以从远程目录加载程序集的插件系统，您可能已经有一个程序集解析处理程序，您只需要扩展它以对附属资源程序集使用不同的搜索行为。如果您没有，那么实现就很重要，因为您基本上要对所有程序集搜索行为负责。我将发布一个有效解决方案的完整代码，这样无论哪种方式你都会被覆盖。首先，您需要在某处 Hook 您的 AssemblyResolve 处理程序，如下所示:

AppDomain.CurrentDomain.AssemblyResolve += ResolveAssemblyReference;

然后假设您有几个变量来保存主应用程序和插件目录的路径信息，如下所示:

string _processAssemblyDirectoryPath;
List<string> _assemblySearchPaths;

然后你需要一个看起来有点像这样的小辅助方法:

static Assembly LoadAssembly(string assemblyPath)
{
    // If the target assembly is already loaded, return the existing assembly instance.
    Assembly[] loadedAssemblies = AppDomain.CurrentDomain.GetAssemblies();
    Assembly targetAssembly = loadedAssemblies.FirstOrDefault((x) => !x.IsDynamic && String.Equals(x.Location, assemblyPath, StringComparison.OrdinalIgnoreCase));
    if (targetAssembly != null)
    {
        return targetAssembly;
    }

    // Attempt to load the target assembly
    return Assembly.LoadFile(assemblyPath);
}

最后，您需要所有重要的 AssemblyResolve 事件处理程序，它看起来有点像这样:

Assembly ResolveAssemblyReference(object sender, ResolveEventArgs args)
{
    // Obtain information about the requested assembly
    AssemblyName targetAssemblyName = new AssemblyName(args.Name);
    string targetAssemblyFileName = targetAssemblyName.Name + ".dll";

    // Handle satellite assembly load requests. Note that prior to .NET 4.0, satellite assemblies didn't get
    // passed to AssemblyResolve handlers. When this was changed, there is a specific guarantee that if null is
    // returned, normal load procedures will be followed for the satellite assembly, IE, it will be located and
    // loaded in the same manner as if this event handler wasn't registered. This isn't sufficient for us
    // though, as the normal load behaviour doesn't correctly locate satellite assemblies where the owning
    // assembly has been loaded using Assembly.LoadFile where the assembly is located in a different folder to
    // the process assembly. We handle that here by performing the satellite assembly search process ourselves.
    // Also note that satellite assemblies are formally documented as requiring the file name extension of
    // ".resources.dll", so detecting satellite assembly load requests by comparing with this known string is a
    // valid approach.
    if (targetAssemblyFileName.EndsWith(".resources.dll"))
    {
        // Retrieve the owning assembly which is requesting the satellite assembly
        string owningAssemblyName = targetAssemblyFileName.Replace(".resources.dll", ".dll");
        Assembly owningAssembly = AppDomain.CurrentDomain.GetAssemblies().FirstOrDefault((x) => x.Location.EndsWith(owningAssemblyName));
        if (owningAssembly == null)
        {
            return null;
        }

        // Retrieve the directory containing the owning assembly
        string owningAssemblyDirectory = Path.GetDirectoryName(owningAssembly.Location);

        // Search for the required satellite assembly in resource subdirectories, and load it if found.
        CultureInfo searchCulture = System.Threading.Thread.CurrentThread.CurrentCulture;
        while (searchCulture != CultureInfo.InvariantCulture)
        {
            string resourceAssemblyPath = Path.Combine(owningAssemblyDirectory, searchCulture.Name, targetAssemblyFileName);
            if (File.Exists(resourceAssemblyPath))
            {
                Assembly resourceAssembly = LoadAssembly(resourceAssemblyPath);
                if (resourceAssembly != null)
                {
                    return resourceAssembly;
                }
            }
            searchCulture = searchCulture.Parent;
        }
        return null;
    }

    // If the target assembly exists in the same directory as the requesting assembly, attempt to load it now.
    string requestingAssemblyPath = (args.RequestingAssembly != null) ? args.RequestingAssembly.Location : String.Empty;
    if (!String.IsNullOrEmpty(requestingAssemblyPath))
    {
        string callingAssemblyDirectory = Path.GetDirectoryName(requestingAssemblyPath);
        string targetAssemblyInCallingDirectoryPath = Path.Combine(callingAssemblyDirectory, targetAssemblyFileName);
        if (File.Exists(targetAssemblyInCallingDirectoryPath))
        {
            try
            {
                return LoadAssembly(targetAssemblyInCallingDirectoryPath);
            }
            catch (Exception ex)
            {
                // Log an error
                return null;
            }
        }
    }

    // If the target assembly exists in the same directory as the process executable, attempt to load it now.
    string processDirectory = _processAssemblyDirectoryPath;
    string targetAssemblyInProcessDirectoryPath = Path.Combine(processDirectory, targetAssemblyFileName);
    if (File.Exists(targetAssemblyInProcessDirectoryPath))
    {
        try
        {
            return LoadAssembly(targetAssemblyInProcessDirectoryPath);
        }
        catch (Exception ex)
        {
            // Log an error
            return null;
        }
    }

    // Build a list of all assemblies with the requested name in the defined list of assembly search paths
    Dictionary<string, AssemblyName> assemblyVersionInfo = new Dictionary<string, AssemblyName>();
    foreach (string assemblyDir in _assemblySearchPaths)
    {
        // If the target assembly doesn't exist in this path, skip it.
        string assemblyPath = Path.Combine(assemblyDir, targetAssemblyFileName);
        if (!File.Exists(assemblyPath))
        {
            continue;
        }

        // Attempt to retrieve detailed information on the name and version of the target assembly
        AssemblyName matchAssemblyName;
        try
        {
            matchAssemblyName = AssemblyName.GetAssemblyName(assemblyPath);
        }
        catch (Exception)
        {
            continue;
        }

        // Add this assembly to the list of possible target assemblies
        assemblyVersionInfo.Add(assemblyPath, matchAssemblyName);
    }

    // Look for an exact match of the target version
    string matchAssemblyPath = assemblyVersionInfo.Where((x) => x.Value == targetAssemblyName).Select((x) => x.Key).FirstOrDefault();
    if (matchAssemblyPath == null)
    {
        // If no exact target version match exists, look for the highest available version.
        Dictionary<string, AssemblyName> assemblyVersionInfoOrdered = assemblyVersionInfo.OrderByDescending((x) => x.Value.Version).ToDictionary((x) => x.Key, (x) => x.Value);
        matchAssemblyPath = assemblyVersionInfoOrdered.Select((x) => x.Key).FirstOrDefault();
    }

    // If no matching assembly was found, log an error, and abort any further processing.
    if (matchAssemblyPath == null)
    {
        return null;
    }

    // If the target assembly is already loaded, return the existing assembly instance.
    Assembly loadedAssembly = AppDomain.CurrentDomain.GetAssemblies().FirstOrDefault((x) => String.Equals(x.Location, matchAssemblyPath, StringComparison.OrdinalIgnoreCase));
    if (loadedAssembly != null)
    {
        return loadedAssembly;
    }

    // Attempt to load the target assembly
    try
    {
        return LoadAssembly(matchAssemblyPath);
    }
    catch (Exception ex)
    {
        // Log an error
    }
    return null;
}

该事件处理程序的第一部分处理附属资源程序集，然后是我用于常规程序集的搜索行为。这应该足以帮助任何人从头开始构建这样的系统。