使用.Net6中的WebApplication打造最小API

  <PropertyGroup>
    <TargetFramework>net6.0</TargetFramework>
    <LangVersion>preview</LangVersion>
  </PropertyGroup>

[AttributeUsage(AttributeTargets.Method)]
    public class WebRouter : Attribute
    {
        public string path;
        public HttpMethod httpMethod;
        public WebRouter(string path)
        {
            this.path = path;
            this.httpMethod = HttpMethod.Post;
        }
        public WebRouter(string path, HttpMethod httpMethod)
        {
            this.path = path;
            this.httpMethod = httpMethod;
        }
    }

public interface IMyService
    {
        Task<MyOutput> Hello(MyInput input);
    }
    public interface IMyRepository
    {
        Task<bool> SaveData(MyOutput data);
    }
    public class MyService : IMyService
    {
        private readonly IMyRepository myRepository;
        public MyService(IMyRepository myRepository)
        {
            this.myRepository = myRepository;
        }
        [WebRouter("/", HttpMethod.Post)]
        public async Task<MyOutput> Hello(MyInput input)
        {
            var result = new MyOutput() { Words = $"hello {input.Name ?? "nobody"}" };
            await myRepository.SaveData(result);
            return await Task.FromResult(result);
        }
    }
    public class MyRepository : IMyRepository
    {
        public async Task<bool> SaveData(MyOutput data)
        {
            Console.WriteLine($"保存成功:{data.Words}");
            return await Task.FromResult(true);
        }
    }

public abstract class DynamicPorxy
    {
        public abstract Delegate Instance { get; set; }
    }
    public class DynamicPorxyImpl<Tsvc, Timpl, Tinput, Toutput> : DynamicPorxy where Timpl : class where Tinput : class where Toutput : class
    {
        public override Delegate Instance { get; set; }
        public DynamicPorxyImpl(MethodInfo method)
        {
            Instance = ([FromServices] IServiceProvider sp, Tinput input) => ExpressionTool.CreateMethodDelegate<Timpl, Tinput, Toutput>(method)(sp.GetService(typeof(Tsvc)) as Timpl, input);
        }
    }
    public class DynamicPorxyImpl<Tsvc, Timpl, Toutput> : DynamicPorxy where Timpl : class where Toutput : class
    {
        public override Delegate Instance { get; set; }
        public DynamicPorxyImpl(MethodInfo method)
        {
            Instance = ([FromServices] IServiceProvider sp) => ExpressionTool.CreateMethodDelegate<Timpl, Toutput>(method)(sp.GetService(typeof(Tsvc)) as Timpl);
        }
    }

public class DynamicPorxyFactory
    {
        public static IEnumerable<(WebRouter, DynamicPorxy)> ReGISterDynamicPorxy()
        {
            foreach (var methodinfo in DependencyContext.Default.CompileLibraries.Where(x => !x.Serviceable && x.Type != "package")
                .Select(x => AssemblyLoadContext.Default.LoadFromAssemblyName(new AssemblyName(x.Name)))
                .SelectMany(x => x.GetTypes().Where(x => !x.IsInterface && x.GetInterfaces().Any()).SelectMany(x => x.GetMethods().Where(y => y.CustomAttributes.Any(z => z.AttributeType == typeof(WebRouter))))))
            {
                var webRouter = methodinfo.GetCustomAttributes(typeof(WebRouter), false).FirstOrDefault() as WebRouter;
                DynamicPorxy dynamicPorxy;
                if (methodinfo.GetParameters().Any())
                    dynamicPorxy = Activator.CreateInstance(typeof(DynamicPorxyImpl<,,,>).MakeGenericType(methodinfo.DeclaringType.GetInterfaces()[0], methodinfo.DeclaringType, methodinfo.GetParameters()[0].ParameterType , methodinfo.ReturnType), new object[] { methodinfo }) as DynamicPorxy;
                else
                    dynamicPorxy = Activator.CreateInstance(typeof(DynamicPorxyImpl<,,>).MakeGenericType(methodinfo.DeclaringType.GetInterfaces()[0], methodinfo.DeclaringType,  methodinfo.ReturnType), new object[] { methodinfo }) as DynamicPorxy;
                yield return (webRouter, dynamicPorxy);
            }
        }
    }

internal class ExpressionTool
    {
        internal static Func<TObj, Tin, Tout> CreateMethodDelegate<TObj, Tin, Tout>(MethodInfo method)
        {
            var mParameter = Expression.Parameter(typeof(TObj), "m");
            var pParameter = Expression.Parameter(typeof(Tin), "p");
            var mcExpression = Expression.Call(mParameter, method, Expression.Convert(pParameter, typeof(Tin)));
            var reExpression = Expression.Convert(mcExpression, typeof(Tout));
            return Expression.Lambda<Func<TObj, Tin, Tout>>(reExpression, mParameter, pParameter).Compile();
        }
        internal static Func<TObj, Tout> CreateMethodDelegate<TObj, Tout>(MethodInfo method)
        {
            var mParameter = Expression.Parameter(typeof(TObj), "m");
            var mcExpression = Expression.Call(mParameter, method);
            var reExpression = Expression.Convert(mcExpression, typeof(Tout));
            return Expression.Lambda<Func<TObj, Tout>>(reExpression, mParameter).Compile();
        }
    }

public static class WebApplicationBuilderExtension
    {
        static Func<string, Delegate, IEndpointConventionBuilder> GetWebApplicationMap(HttpMethod httpMethod, WebApplication webApplication) => (httpMethod) switch
                {
                    (HttpMethod.Get) => webApplication.MapGet,
                    (HttpMethod.Post) => webApplication.MapPost,
                    (HttpMethod.Put) => webApplication.MapPut,
                    (HttpMethod.Delete) => webApplication.MapDelete,
                    _ => webApplication.MapGet
                };
        public static WebApplication RegisterDependencyAndMapDelegate(this WebApplicationBuilder webApplicationBuilder, Action<IServiceCollection> registerDependencyAction, Func<IEnumerable<(WebRouter webRouter, DynamicPorxy dynamicPorxy)>> mapProxyBuilder)
        {
            webApplicationBuilder.Host.ConfigureServices((ctx, services) =>
            {
                registerDependencyAction(services);
            });
            var webApplication = webApplicationBuilder.Build();
            mapProxyBuilder().ToList().ForEach(item => GetWebApplicationMap(item.webRouter.httpMethod, webApplication)(item.webRouter.path, item.dynamicPorxy.Instance));
            return webApplication;
        }
    }

public class MyServiceDependency
    {
        public static void Register(IServiceCollection services)
        {
            services.AddScoped<IMyService, MyService>();
            services.AddScoped<IMyRepository, MyRepository>();
        }
    }

await WebApplication.CreateBuilder().RegisterDependencyAndMapDelegate(MyServiceDependency.Register,DynamicPorxyFactory.RegisterDynamicPorxy).RunAsync("http://*:80");