网络核心 Web api 项目的 class 库中的依赖注入

Question

我有一个 .NET Core WEB API 项目，我想作为 .NET CORE Class 库成为多个“项目”的容器。

我有的是：

带有 .NET Core Web API 项目的解决方案“Orbit”。
带有 .NET Core Class 库的解决方案“SpaceRadar”。

首先，在我的“轨道”项目中，Startup class，到目前为止我所做的：

  public void ConfigureServices(IServiceCollection services)
    {

        this.ConfigureMVC(services);
        this.ConfigureIOC(services);

    }

    private void ConfigureMVC(IServiceCollection services)
    {
        IMvcBuilder mvcBuilder = services.AddMvc(option => { option.EnableEndpointRouting = false; });
        // for each assembly inside modules directory, add the controllers
        foreach (string assemblyPath in Directory.GetFiles($"{System.AppDomain.CurrentDomain.BaseDirectory}/Modules", "*.dll", SearchOption.AllDirectories))
        {
            var assembly = Assembly.LoadFile(assemblyPath);
            mvcBuilder.AddApplicationPart(assembly);
        }
    }

这部分效果很好，因为我们可以触发在我的 SpaceRadar 项目中定义的控制器。但是我想在我的 class 库项目中使用依赖注入，如果可能的话，通过扫描 dll 来获取扩展 IScopedServices / ISingletonServices / ITransientServices 的所有类型。

但老实说，我不知道在哪里注册我的接口及其各自的实现。我试过这个解决方案：

private void ConfigureIOC(IServiceCollection services)
    {

        // Store all the type that need to be injected in the IOC system
        List<Type> implementationTypes = new List<Type>();
        List<Type> singletons = new List<Type>();
        List<Type> scopeds = new List<Type>();
        List<Type> transients = new List<Type>();

        // for each assembly, load it, populate the type list of things to be injected 
        foreach (string assemblyPath in Directory.GetFiles(System.AppDomain.CurrentDomain.BaseDirectory, "*.dll", SearchOption.AllDirectories))
        {    
            var assembly = System.Runtime.Loader.AssemblyLoadContext.Default.LoadFromAssemblyPath(assemblyPath);
            implementationTypes.AddRange(assembly.GetExportedTypes().Where(type => type.IsClass && (type.GetInterface("ISingletonServices") != null || type.GetInterface("IScopedServices") != null || type.GetInterface("ITransientServices") != null)));
            singletons.AddRange(assembly.GetExportedTypes().Where(type => type.IsInterface && type.GetInterface("ISingletonServices") != null));
            scopeds.AddRange(assembly.GetExportedTypes().Where(type => type.IsInterface && type.GetInterface("IScopedServices") != null));
            transients.AddRange(assembly.GetExportedTypes().Where(type => type.IsInterface && type.GetInterface("ITransientServices") != null));
        }

        // Register into the service collection
        foreach (Type type in singletons)
        {
            services.AddSingleton(type, implementationTypes.Single(t => t.GetInterface(type.FullName) != null));
        }
        foreach (Type type in scopeds)
        {
            services.AddScoped(type, implementationTypes.Single(t => t.GetInterface(type.FullName) != null));
        }
        foreach (Type type in transients)
        {
            services.AddTransient(type, implementationTypes.Single(t => t.GetInterface(type.FullName) != null));
        }

}

不过好像是程序集的上下文有问题。我也尝试了 Assembly.LoadFrom() 但没有用，在博客

上找到的 ReaderLoadContext 解决方案

using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using System.Runtime.Loader;
using System.Threading.Tasks;

namespace Orbit
{
    public class ReaderLoadContext : AssemblyLoadContext
    {
        private AssemblyDependencyResolver _resolver;

        public ReaderLoadContext(string readerLocation)
        {
            _resolver = new AssemblyDependencyResolver(readerLocation);
        }

        protected override Assembly Load(AssemblyName assemblyName)
        {
            string assemblyPath = _resolver.ResolveAssemblyToPath(assemblyName);
            if (assemblyPath != null)
            {
                return LoadFromAssemblyPath(assemblyPath);
            }

            return null;
        }

        protected override IntPtr LoadUnmanagedDll(string unmanagedDllName)
        {
            string libraryPath = _resolver.ResolveUnmanagedDllToPath(unmanagedDllName);

            if (libraryPath != null)
            {
                return LoadUnmanagedDllFromPath(libraryPath);
            }

            return IntPtr.Zero;
        }
    }
}

甚至在程序集内调用“setup”方法


        private void ConfigureIOC(IServiceCollection services)
        {
            // for each assembly, load it, add the controller into the mvcBuilder and populate the type list of things to be injected 
            foreach (string assemblyPath in Directory.GetFiles($"{System.AppDomain.CurrentDomain.BaseDirectory}/Modules", "*.dll", SearchOption.AllDirectories))
            {
                Assembly assembly = Assembly.LoadFrom(assemblyPath);
                Type startup = assembly.GetTypes().SingleOrDefault(t => t.Name == "Startup");
                if (startup != null)
                {
                    var setupMethod = startup.GetMethod("Setup");
                    setupMethod.Invoke(setupMethod, new Object[] { services });
                }
            }
        }

在我的 class 图书馆里

public static void Setup(IServiceCollection services)
        {
            
            List<Type> implementationTypes = new List<Type>();
            List<Type> singletons = new List<Type>();
            List<Type> scopeds = new List<Type>();
            List<Type> transients = new List<Type>();

            foreach (string assemblyPath in Directory.GetFiles(Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location), "*.dll", SearchOption.AllDirectories))
            {
                var assembly = Assembly.Load(assemblyPath);
                // get all Singleton, Scoped and Transient interfaces
                implementationTypes.AddRange(assembly.GetTypes().Where(type => type.IsClass && (type.GetInterface("ISingletonServices") != null || type.GetInterface("IScopedServices") != null || type.GetInterface("ITransientServices") != null)));
                singletons.AddRange(assembly.GetTypes().Where(type => type.IsInterface && type.GetInterface("ISingletonServices") != null));
                scopeds.AddRange(assembly.GetTypes().Where(type => type.IsInterface && type.GetInterface("IScopedServices") != null));
                transients.AddRange(assembly.GetTypes().Where(type => type.IsInterface && type.GetInterface("ITransientServices") != null));
            }

            // Register into the service collection
            foreach (Type type in singletons)
            {
                services.AddSingleton(type, implementationTypes.Single(t => t.GetInterface(type.FullName) != null));
            }
            foreach (Type type in scopeds)
            {
                services.AddScoped(type, implementationTypes.Single(t => t.GetInterface(type.FullName) != null));
            }
            foreach (Type type in transients)
            {
                services.AddTransient(type, implementationTypes.Single(t => t.GetInterface(type.FullName) != null));
            }
            
        }

我还尝试了 HostingStartup 属性

[assembly: HostingStartup(typeof(SpaceRadar.ServiceKeyInjection))]
namespace SpaceRadar
{
    public class ServiceKeyInjection : IHostingStartup
    {
        public void Configure(IWebHostBuilder builder)
        {
            builder.ConfigureServices((context, services) => {
                List<Type> implementationTypes = new List<Type>();
                List<Type> singletons = new List<Type>();
                List<Type> scopeds = new List<Type>();
                List<Type> transients = new List<Type>();

                foreach (string assemblyPath in Directory.GetFiles(Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location), "*.dll", SearchOption.AllDirectories))
                {
                    var assembly = Assembly.Load(assemblyPath);
                    // get all Singleton, Scoped and Transient interfaces
                    implementationTypes.AddRange(assembly.GetTypes().Where(type => type.IsClass && (type.GetInterface("ISingletonServices") != null || type.GetInterface("IScopedServices") != null || type.GetInterface("ITransientServices") != null)));
                    singletons.AddRange(assembly.GetTypes().Where(type => type.IsInterface && type.GetInterface("ISingletonServices") != null));
                    scopeds.AddRange(assembly.GetTypes().Where(type => type.IsInterface && type.GetInterface("IScopedServices") != null));
                    transients.AddRange(assembly.GetTypes().Where(type => type.IsInterface && type.GetInterface("ITransientServices") != null));
                }

                // Register into the service collection
                foreach (Type type in singletons)
                {
                    services.AddSingleton(type, implementationTypes.Single(t => t.GetInterface(type.FullName) != null));
                }
                foreach (Type type in scopeds)
                {
                    services.AddScoped(type, implementationTypes.Single(t => t.GetInterface(type.FullName) != null));
                }
                foreach (Type type in transients)
                {
                    services.AddTransient(type, implementationTypes.Single(t => t.GetInterface(type.FullName) != null));
                }
            });
        }
    }
}

所有这些解决方案都不允许我在 class 库中使用这种控制器：

 public class RadarControllers : BaseControllers
    {
        private readonly IRadarServices _radarServices;

        public RadarControllers(IRadarServices radarServices)
        {
            _radarServices = radarServices;
        }

        [HttpGet("radars")]
        public async Task<IActionResult> GetRadars(CancellationToken cancellationToken)
        {
            IList<string> data = await _radarServices.GetRadars(cancellationToken);
            return Ok(data);
        }
    }

如何进行此依赖项注入？谢谢。

Answer 1

我终于找到了解决这个问题的方法。问题是在每个项目上，程序集名称都是相同的（例如：“服务”）。 .Net 核心不喜欢这样，似乎如果我尝试通过 AssemblyLoadContext.Default.LoadFromAssemblyPath 加载，无论要指示的路径如何，它都会继续加载相同的程序集。

在项目上，我只需右键单击 > 属性并将程序集名称更改为另一个。多亏了这一点，AssemblyLoadContext.Default.LoadFromAssemblyPath(assemblyPath) 有效。

例如，如果我有项目 A 和 B，我将程序集名称服务重命名为 A.Services 和 B.Services

所以 dll 现在是 A.Services.dll 而不是 Services.dll

网络核心 Web api 项目的 class 库中的依赖注入

Dependency Injection inside class library for a net core web api project

c#

dll

inversion-of-control

.net-core

webapi