Question

构建后，我需要从某些C＃类生成typescript文件。

我创建了dotnet cli tool并添加了构建后事件

dotnet tsgenerator "$(TargetPath)"

其中$(TargetPath)是指向宏的宏，例如D:\Test\bin\Release\netcoreapp2.0\my.dll

接下来，我尝试用以下方式加载程序集：

public static void Main(string[] args)
{
    var dllPath = args[0]; // "D:\Test\bin\Release\netcoreapp2.0\my.dll"
    var assembly = Assembly.LoadFile(dllPath);
    var types = assembly.GetExportedTypes(); // Throws exception
}

但是我得到ReflectionTypeLoadException对于某些引用程序集（例如Could not load file or assembly）说Microsoft.AspNetCore.Antiforgery。

我如何为.NET Core应用程序加载程序集？

Answer 1

我在github issue找到了解决方案。 amits1995和angelcalvasp的消息。

我在我的csproj中添加了<CopyLocalLockFileAssemblies>true</CopyLocalLockFileAssemblies>，并使用以下代码加载了程序集：

public static class AssemblyLoader
{
    public static Assembly LoadFromAssemblyPath(string assemblyFullPath)
    {
        var fileNameWithOutExtension = Path.GetFileNameWithoutExtension(assemblyFullPath);
        var fileName = Path.GetFileName(assemblyFullPath);
        var directory = Path.GetDirectoryName(assemblyFullPath);

        var inCompileLibraries = DependencyContext.Default.CompileLibraries.Any(l => l.Name.Equals(fileNameWithOutExtension, StringComparison.OrdinalIgnoreCase));
        var inRuntimeLibraries = DependencyContext.Default.RuntimeLibraries.Any(l => l.Name.Equals(fileNameWithOutExtension, StringComparison.OrdinalIgnoreCase));

        var assembly = (inCompileLibraries || inRuntimeLibraries)
            ? Assembly.Load(new AssemblyName(fileNameWithOutExtension))
            : AssemblyLoadContext.Default.LoadFromAssemblyPath(assemblyFullPath);

        if (assembly != null)
            LoadReferencedAssemblies(assembly, fileName, directory);

        return assembly;
    }

    private static void LoadReferencedAssemblies(Assembly assembly, string fileName, string directory)
    {
        var filesInDirectory = Directory.GetFiles(directory).Where(x => x != fileName).Select(x => Path.GetFileNameWithoutExtension(x)).ToList();
        var references = assembly.GetReferencedAssemblies();

        foreach (var reference in references)
        {
            if (filesInDirectory.Contains(reference.Name))
            {
                var loadFileName = reference.Name + ".dll";
                var path = Path.Combine(directory, loadFileName);
                var loadedAssembly = AssemblyLoadContext.Default.LoadFromAssemblyPath(path);
                if (loadedAssembly != null)
                    LoadReferencedAssemblies(loadedAssembly, loadFileName, directory);
            }
        }
    }
}

用法：

public static void Main(string[] args)
{
    var dllPath = args[0]; // "D:\Test\bin\Release\netcoreapp2.0\my.dll"
    var assembly = AssemblyLoader.LoadFromAssemblyPath(dllPath);
    var types = assembly.GetExportedTypes(); // No exceptions
}

Answer 2

您可以加载程序集，但是GetTypes()和GetExportedTypes()依赖于该程序集中的公共类，如果它们具有外部引用，则会出现此异常。

答案： 这意味着该程序集的Types依赖于当前.NetCore在运行时无法访问的其他程序集，因为它无法连接到其他相关程序集

解决方案：
获取DLL程序集的依赖关系并将其全部编译，然后迭代加载每个程序集以获取所有ExportedTypes（即公开可见的Types）

代码：

using System;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Runtime.Loader;
using Microsoft.Extensions.DependencyModel;// add this nuget

class Program
{
    static void Main(string[] args)
    {
        var asl = new AssemblyLoader();
        var asm = asl.LoadFromAssemblyPath(@"C:\temp\Microsoft.AspNetCore.Antiforgery.dll");
        try
        {

            var y = asm.GetExportedTypes();
            Console.WriteLine(y);
        }
        catch (Exception e1)
        {
            Console.WriteLine("Got exception at first attempt of GetExportedTypes ");
            Console.WriteLine("\t*********" + e1.Message + "**************");

            var deped = asl.CallForDependency(asm.GetName());

            try
            {
                Console.WriteLine("\n" + deped.ToString());
                Console.WriteLine("----------All Exported Types------------");

                foreach (var item in deped.ExportedTypes)
                {
                    Console.WriteLine(item);
                }
            }
            catch (Exception e2)
            {

                Console.WriteLine("Got exception at second attempt of GetExportedTypes ");
                Console.WriteLine("\t*********" + e2.Message + "**************");
            }

        }
        Console.ReadLine();

    }
}

public class AssemblyLoader :AssemblyLoadContext
{
    protected override Assembly Load(AssemblyName assemblyName)
    {
        var deps = DependencyContext.Default;
        var res = deps.CompileLibraries.Where(d => d.Name.Contains(assemblyName.Name)).ToList();
        var assembly = Assembly.Load(new AssemblyName(res.First().Name));
        return assembly;
    }

    public Assembly CallForDependency(AssemblyName assemblyName)
    {
        return this.Load(assemblyName);
    }
}

输出：

Got exception at first attempt of GetExportedTypes
        *********Could not load file or assembly 'mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'. An operation is not legal in the current state. (Exception from HRESULT: 0x80131509)**************

Microsoft.AspNetCore.Antiforgery, Version=2.1.1.0, Culture=neutral, PublicKeyToken=adb9793829ddae60
----------All Exported Types------------
Microsoft.Extensions.DependencyInjection.AntiforgeryServiceCollectionExtensions
Microsoft.AspNetCore.Antiforgery.AntiforgeryOptions
Microsoft.AspNetCore.Antiforgery.AntiforgeryTokenSet
Microsoft.AspNetCore.Antiforgery.AntiforgeryValidationException
Microsoft.AspNetCore.Antiforgery.IAntiforgery
Microsoft.AspNetCore.Antiforgery.IAntiforgeryAdditionalDataProvider
Microsoft.AspNetCore.Antiforgery.Internal.AntiforgeryFeature
Microsoft.AspNetCore.Antiforgery.Internal.AntiforgeryOptionsSetup
Microsoft.AspNetCore.Antiforgery.Internal.AntiforgerySerializationContext
Microsoft.AspNetCore.Antiforgery.Internal.AntiforgerySerializationContextPooledObjectPolicy
Microsoft.AspNetCore.Antiforgery.Internal.AntiforgeryToken
Microsoft.AspNetCore.Antiforgery.Internal.BinaryBlob
Microsoft.AspNetCore.Antiforgery.Internal.CryptographyAlgorithms
Microsoft.AspNetCore.Antiforgery.Internal.DefaultAntiforgery
Microsoft.AspNetCore.Antiforgery.Internal.DefaultAntiforgeryAdditionalDataProvider
Microsoft.AspNetCore.Antiforgery.Internal.DefaultAntiforgeryTokenGenerator
Microsoft.AspNetCore.Antiforgery.Internal.DefaultAntiforgeryTokenSerializer
Microsoft.AspNetCore.Antiforgery.Internal.DefaultAntiforgeryTokenStore
Microsoft.AspNetCore.Antiforgery.Internal.DefaultClaimUidExtractor
Microsoft.AspNetCore.Antiforgery.Internal.IAntiforgeryFeature
Microsoft.AspNetCore.Antiforgery.Internal.IAntiforgeryTokenGenerator
Microsoft.AspNetCore.Antiforgery.Internal.IAntiforgeryTokenSerializer
Microsoft.AspNetCore.Antiforgery.Internal.IAntiforgeryTokenStore
Microsoft.AspNetCore.Antiforgery.Internal.IClaimUidExtractor

对ReflectionTypeLoadException的引用和说明： Assembly.GetTypes Method ()

ReflectionTypeLoadException

程序集包含一种或多种无法加载的类型。的   此异常的Types属性返回的数组包含一个Type   每种加载类型的对象，每种可能加载的类型为null   LoaderExceptions属性包含一个   每种无法加载的类型的异常。

备注

返回的数组包含嵌套类型。

如果在程序集和其中的类型上调用了GetTypes方法   程序集依赖于尚未存在的程序集中的类型   已加载（例如，如果它来自第二个类型   集合），则抛出ReflectionTypeLoadException。例如这个   如果第一个装配件中装有   ReflectionOnlyLoad或ReflectionOnlyLoadFrom方法，第二种   程序集未加载。加载程序集时也可能发生   如果不能使用第二个程序集，则使用Load和LoadFile方法   在调用GetTypes方法时位于。

注意

如果类型已转发到另一个程序集，则不包含   在返回的数组中。有关类型转发的信息，请参见类型   在Common Language Runtime中转发。

已链接：

Answer 3

尝试使用LoadFrom方法而不是LoadFile加载到程序集中。

public static void Main(string[] args)
{
    var dllPath = args[0]; // "D:\Test\bin\Release\netcoreapp2.0\my.dll"
    var assembly = Assembly.LoadFrom(dllPath);
    var types = assembly.GetExportedTypes(); // Throws exception
}

您还需要将ddl文件中的相同引用添加到当前项目中，以便定义类型。

.NET Core Assembly.LoadFile在PostBuild事件

3 个答案: