如何在 .NET 中运行时将文件夹添加到程序集搜索路径？
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How to add folder to assembly search path at runtime in .NET?
提问by isobretatel
My DLLs are loaded by a third-party application, which we can not customize. My assemblies have to be located in their own folder. I can not put them into GAC (my application has a requirement to be deployed using XCOPY). When the root DLL tries to load resource or type from another DLL (in the same folder), the loading fails (FileNotFound). Is it possible to add the folder where my DLLs are located to the assembly search path programmatically (from the root DLL)? I am not allowed to change the configuration files of the application.
我的 DLL 是由第三方应用程序加载的，我们无法对其进行自定义。我的程序集必须位于它们自己的文件夹中。我无法将它们放入 GAC（我的应用程序要求使用 XCOPY 进行部署）。当根 DLL 尝试从另一个 DLL（在同一文件夹中）加载资源或类型时，加载失败 (FileNotFound)。是否可以以编程方式（从根 DLL）将我的 DLL 所在的文件夹添加到程序集搜索路径中？我不允许更改应用程序的配置文件。
回答by Mattias S
Sounds like you could use the AppDomain.AssemblyResolve event and manually load the dependencies from your DLL directory.
听起来您可以使用 AppDomain.AssemblyResolve 事件并从您的 DLL 目录手动加载依赖项。
Edit (from the comment):
编辑（来自评论）：
AppDomain currentDomain = AppDomain.CurrentDomain;
currentDomain.AssemblyResolve += new ResolveEventHandler(LoadFromSameFolder);
static Assembly LoadFromSameFolder(object sender, ResolveEventArgs args)
{
string folderPath = Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location);
string assemblyPath = Path.Combine(folderPath, new AssemblyName(args.Name).Name + ".dll");
if (!File.Exists(assemblyPath)) return null;
Assembly assembly = Assembly.LoadFrom(assemblyPath);
return assembly;
}
回答by Mark Seemann
You can add a probing pathto your application's .config file, but it will only work if the probing path is a contained within your application's base directory.
您可以将探测路径添加到应用程序的 .config 文件中，但只有当探测路径包含在应用程序的基目录中时，它才会起作用。
回答by bubi
Update for Framework 4
框架 4 的更新
Since Framework 4 raise the AssemblyResolve event also for resources actually this handler works better. It's based on the concept that localizations are in app subdirectories (one for localization with the name of the culture i.e. C:\MyApp\it for Italian) Inside there are resources file. The handler works also if the localization is country-region i.e. it-IT or pt-BR. In this case the handler "might be called multiple times: once for each culture in the fallback chain" [from MSDN]. This means that if we return null for "it-IT" resource file the framework raises the event asking for "it".
由于框架 4 也为资源引发了 AssemblyResolve 事件，实际上这个处理程序工作得更好。它基于本地化位于应用程序子目录中的概念（一个用于本地化的文化名称，即 C:\MyApp\it 用于意大利语）里面有资源文件。如果本地化是国家区域，即 it-IT 或 pt-BR，处理程序也能工作。在这种情况下，处理程序“可能被多次调用：对于回退链中的每个文化一次”[来自 MSDN]。这意味着，如果我们为“it-IT”资源文件返回 null，则框架会引发请求“it”的事件。
Event hook
事件挂钩
AppDomain currentDomain = AppDomain.CurrentDomain;
currentDomain.AssemblyResolve += new ResolveEventHandler(currentDomain_AssemblyResolve);
Event handler
事件处理程序
Assembly currentDomain_AssemblyResolve(object sender, ResolveEventArgs args)
{
//This handler is called only when the common language runtime tries to bind to the assembly and fails.
Assembly executingAssembly = Assembly.GetExecutingAssembly();
string applicationDirectory = Path.GetDirectoryName(executingAssembly.Location);
string[] fields = args.Name.Split(',');
string assemblyName = fields[0];
string assemblyCulture;
if (fields.Length < 2)
assemblyCulture = null;
else
assemblyCulture = fields[2].Substring(fields[2].IndexOf('=') + 1);
string assemblyFileName = assemblyName + ".dll";
string assemblyPath;
if (assemblyName.EndsWith(".resources"))
{
// Specific resources are located in app subdirectories
string resourceDirectory = Path.Combine(applicationDirectory, assemblyCulture);
assemblyPath = Path.Combine(resourceDirectory, assemblyFileName);
}
else
{
assemblyPath = Path.Combine(applicationDirectory, assemblyFileName);
}
if (File.Exists(assemblyPath))
{
//Load the assembly from the specified path.
Assembly loadingAssembly = Assembly.LoadFrom(assemblyPath);
//Return the loaded assembly.
return loadingAssembly;
}
else
{
return null;
}
}
回答by nawfal
The best explanation from MS itself:
MS 本身的最佳解释：
AppDomain currentDomain = AppDomain.CurrentDomain;
currentDomain.AssemblyResolve += new ResolveEventHandler(MyResolveEventHandler);
private Assembly MyResolveEventHandler(object sender, ResolveEventArgs args)
{
//This handler is called only when the common language runtime tries to bind to the assembly and fails.
//Retrieve the list of referenced assemblies in an array of AssemblyName.
Assembly MyAssembly, objExecutingAssembly;
string strTempAssmbPath = "";
objExecutingAssembly = Assembly.GetExecutingAssembly();
AssemblyName[] arrReferencedAssmbNames = objExecutingAssembly.GetReferencedAssemblies();
//Loop through the array of referenced assembly names.
foreach(AssemblyName strAssmbName in arrReferencedAssmbNames)
{
//Check for the assembly names that have raised the "AssemblyResolve" event.
if(strAssmbName.FullName.Substring(0, strAssmbName.FullName.IndexOf(",")) == args.Name.Substring(0, args.Name.IndexOf(",")))
{
//Build the path of the assembly from where it has to be loaded.
strTempAssmbPath = "C:\Myassemblies\" + args.Name.Substring(0,args.Name.IndexOf(","))+".dll";
break;
}
}
//Load the assembly from the specified path.
MyAssembly = Assembly.LoadFrom(strTempAssmbPath);
//Return the loaded assembly.
return MyAssembly;
}
回答by msarahan
For C++/CLI users, here is @Mattias S' answer (which works for me):
对于 C++/CLI 用户，这是 @Mattias S 的回答（对我有用）：
using namespace System;
using namespace System::IO;
using namespace System::Reflection;
static Assembly ^LoadFromSameFolder(Object ^sender, ResolveEventArgs ^args)
{
String ^folderPath = Path::GetDirectoryName(Assembly::GetExecutingAssembly()->Location);
String ^assemblyPath = Path::Combine(folderPath, (gcnew AssemblyName(args->Name))->Name + ".dll");
if (File::Exists(assemblyPath) == false) return nullptr;
Assembly ^assembly = Assembly::LoadFrom(assemblyPath);
return assembly;
}
// put this somewhere you know it will run (early, when the DLL gets loaded)
System::AppDomain ^currentDomain = AppDomain::CurrentDomain;
currentDomain->AssemblyResolve += gcnew ResolveEventHandler(LoadFromSameFolder);
回答by Aryéh Radlé
I've used @Mattias S' solution. If you actually want to resolve dependencies from the same folder - you should try using Requesting assemblylocation, as shown below. args.RequestingAssemblyshould be checked for nullity.
我使用了@Mattias S 的解决方案。如果您确实想从同一文件夹解析依赖项 - 您应该尝试使用请求程序集位置，如下所示。args.RequestingAssembly应检查是否无效。
System.AppDomain.CurrentDomain.AssemblyResolve += (s, args) =>
{
var loadedAssembly = System.AppDomain.CurrentDomain.GetAssemblies().Where(a => a.FullName == args.Name).FirstOrDefault();
if(loadedAssembly != null)
{
return loadedAssembly;
}
if (args.RequestingAssembly == null) return null;
string folderPath = Path.GetDirectoryName(args.RequestingAssembly.Location);
string rawAssemblyPath = Path.Combine(folderPath, new System.Reflection.AssemblyName(args.Name).Name);
string assemblyPath = rawAssemblyPath + ".dll";
if (!File.Exists(assemblyPath))
{
assemblyPath = rawAssemblyPath + ".exe";
if (!File.Exists(assemblyPath)) return null;
}
var assembly = System.Reflection.Assembly.LoadFrom(assemblyPath);
return assembly;
};
回答by Vincent Lidou
look into AppDomain.AppendPrivatePath (deprecated) or AppDomainSetup.PrivateBinPath
查看 AppDomain.AppendPrivatePath（已弃用）或 AppDomainSetup.PrivateBinPath
回答by sommmen
I came here from another (marked duplicate) questionabout adding the probing tag to the App.Config file.
我是从另一个（标记为重复的）问题来到这里的，该问题是关于将探测标签添加到 App.Config 文件的。
I want to add a sidenote to this - Visual studio had already generated an App.config file, however adding the probing tag to the pregenerated runtime tag did not work! you need a seperate runtime tag with the probing tag included. In short, your App.Config should look like this:
我想为此添加一个旁注 - Visual Studio 已经生成了一个 App.config 文件，但是将探测标记添加到预生成的运行时标记不起作用！您需要一个包含探测标签的单独运行时标签。简而言之，您的 App.Config 应如下所示：
<?xml version="1.0" encoding="utf-8"?>
<configuration>
<startup>
<supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.7.2" />
</startup>
<runtime>
<assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
<dependentAssembly>
<assemblyIdentity name="System.Text.Encoding.CodePages" publicKeyToken="b03f5f7f11d50a3a" culture="neutral" />
<bindingRedirect oldVersion="0.0.0.0-4.1.1.0" newVersion="4.1.1.0" />
</dependentAssembly>
</assemblyBinding>
</runtime>
<!-- Discover assemblies in /lib -->
<runtime>
<assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
<probing privatePath="lib" />
</assemblyBinding>
</runtime>
</configuration>
This took some time to figure out so I am posting it here. Also credits to The PrettyBin NuGet Package. It is a package that moves the dlls automatically. I liked a more manual approach so I did not use it.
这花了一些时间才弄明白，所以我把它贴在这里。也归功于PrettyBin NuGet 包。它是一个自动移动 dll 的包。我喜欢更手动的方法，所以我没有使用它。
Also - here is a post build script that copies all .dll/.xml/.pdb to /Lib. This unclutters the /debug (or /release) folder, what I think people try to achieve.
另外 - 这是一个将所有 .dll/.xml/.pdb 复制到 /Lib 的构建后脚本。这整理了 /debug（或 /release）文件夹，我认为这是人们试图实现的目标。
:: Moves files to a subdirectory, to unclutter the application folder
:: Note that the new subdirectory should be probed so the dlls can be found.
SET path=$(TargetDir)\lib
if not exist "%path%" mkdir "%path%"
del /S /Q "%path%"
move /Y $(TargetDir)*.dll "%path%"
move /Y $(TargetDir)*.xml "%path%"
move /Y $(TargetDir)*.pdb "%path%"
