.NET Core中的程序集加载 [英] Assembly Loading in .NET Core

问题描述

使用VS2017 RC，.NET Core

Using VS2017 RC, .NET Core

我正在尝试从文件加载程序集。
该程序集的依赖项位于同一文件夹中。

I am trying to load an assembly from a file. The dependencies of this assembly are in the same folder.

我正在使用 AssemblyLoadContext.Default.LoadFromAssemblyPath 。

我意识到 LoadFromAssemblyPath 专门加载请求的程序集，而忽略其依赖关系；尝试遍历程序集类型的任何尝试均会失败，并出现 System.Reflection.ReflectionTypeLoadException 。

I realize LoadFromAssemblyPath exclusively loads the requested assembly, ignoring its dependencies; any attempt to iterate through the assembly types fails with a System.Reflection.ReflectionTypeLoadException.

LoaderExceptions 包含 System.IO.FileNotFoundException 的列表。

我好奇为什么会这样，因为所有必需的文件都在同一个文件夹中。

I'm curious as to why this is the case, since all the required files are in the same folder.

我也尝试将所有* .dll文件加载到一个文件夹中，但是

I also tried to load all *.dll files in a folder, but some surprisingly fail with a System.IO.FileLoadException.

我在做什么错了？

编辑：我不想依靠.deps文件（因此排除了DependencyContext）。

I wouldn't want to rely on the .deps file (thus ruling out DependencyContext). Is it possible?

推荐答案

对我有用的是在Resolving事件中注册一个句柄并在需要时按需加载所需的程序集LoadFromAssemblyPath需要依赖项。请注意，这是经过数小时的反复试验而得出的我的解决方案，因此它可能不是最理想的方法。现在它对我有用。这是我的代码：

Well what works for me is to register a handle with the Resolving event and load required assemblies on demand when LoadFromAssemblyPath needs dependencies. Be aware that this my solution from hours of trial and error, so it might not be the most ideal way. It works for me by now though. Here's my code:

    AssemblyLoadContext.Default.Resolving += (context, name) =>
    {
        // avoid loading *.resources dlls, because of: https://github.com/dotnet/coreclr/issues/8416
        if (name.Name.EndsWith("resources"))
        {
            return null;
        }

        var dependencies = DependencyContext.Default.RuntimeLibraries;
        foreach (var library in dependencies)
        {
            if (IsCandidateLibrary(library, name))
            {
                return context.LoadFromAssemblyName(new AssemblyName(library.Name));
            }
        }

        var foundDlls = Directory.GetFileSystemEntries(new FileInfo(<YOUR_PATH_HERE>).FullName, name.Name + ".dll", SearchOption.AllDirectories);
        if (foundDlls.Any())
        {
            return context.LoadFromAssemblyPath(foundDlls[0]);
        }

        return context.LoadFromAssemblyName(name);
    };
}
private static bool IsCandidateLibrary(RuntimeLibrary library, AssemblyName assemblyName)
{
    return (library.Name == (assemblyName.Name))
            || (library.Dependencies.Any(d => d.Name.StartsWith(assemblyName.Name)));
}

IsCandidateLibrary（）位起源于此：
http://www.michael-whelan.net/replacing-appdomain-in-dotnet -core /

The IsCandidateLibrary() bit originates from there: http://www.michael-whelan.net/replacing-appdomain-in-dotnet-core/

我认为您可以忽略此部分以及整个DependencyContext部分，但是它充当了缓存，避免了一次又一次地重新加载相同的程序集。所以我保留了它。

I think you could omit this and the whole DependencyContext part, but it acts as a cache and avoids reloading the same assemblies over and over again. So i kept it.

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