以下是使用VB.NET实现的方案，分别针对传统ASP.NET（System.Web）和ASP.NET Core 两种环境，实现无需手动配置handlers，仅将 DLL 放入bin目录即可处理 HTTP 请求的功能。

一、传统ASP.NET（System.Web）方案：自动注册 HTTP 模块

通过PreApplicationStartMethod特性实现模块自动注册，放入bin目录后即可生效。

VB.NET自动注册HTTP模块处理请求

Imports System.Web' 程序集级特性：指定应用启动时自动执行的初始化方法
<Assembly: PreApplicationStartMethod(GetType(UploadToolInitializer), "Initialize")> Namespace XiaoYaoWebCore' 自定义HTTP模块，处理请求逻辑Public Class UploadToolModuleImplements IHttpModulePublic Sub Init(context As HttpApplication) Implements IHttpModule.Init' 注册请求开始事件AddHandler context.BeginRequest, AddressOf OnBeginRequestEnd SubPrivate Sub OnBeginRequest(sender As Object, e As EventArgs)Dim app As HttpApplication = DirectCast(sender, HttpApplication)Dim request As HttpRequest = app.Context.RequestDim response As HttpResponse = app.Context.Response' 只处理特定路径的请求If request.Path.StartsWith("/UploadTool", StringComparison.OrdinalIgnoreCase) Then' 这里是你的业务处理逻辑response.ContentType = "text/plain"response.Write("VB.NET自动加载模块处理成功：" & DateTime.Now.ToString())response.End() ' 终止后续处理End IfEnd SubPublic Sub Dispose() Implements IHttpModule.Dispose' 清理资源（如果需要）End SubEnd Class' 初始化器：负责自动注册模块Public NotInheritable Class UploadToolInitializerPrivate Sub New()End Sub' 应用启动时自动调用此方法Public Shared Sub Initialize()' 向ASP.NET管道注册模块HttpApplication.RegisterModule(GetType(UploadToolModule))End SubEnd Class
End Namespace

二、ASP.NET Core 方案：自动扫描并注册中间件

主项目提前配置扫描逻辑，DLL 中的中间件会被自动发现并注册。

1. DLL 中的中间件实现（VB.NET）

VB.NET ASP.NET Core中间件

Imports Microsoft.AspNetCore.Http
Imports System.Threading.TasksNamespace XiaoYaoWebCorePublic Class UploadToolMiddlewarePrivate ReadOnly _next As RequestDelegate' 构造函数，接收下一个中间件Public Sub New(next As RequestDelegate)_next = nextEnd Sub' 处理请求的核心方法Public Async Function InvokeAsync(context As HttpContext) As Task' 匹配特定路径If context.Request.Path.StartsWithSegments("/UploadTool") Thencontext.Response.ContentType = "text/plain"Await context.Response.WriteAsync("VB.NET Core中间件自动处理成功：" & DateTime.Now.ToString())Return ' 处理完成，不再调用下一个中间件End If' 不匹配则传递给下一个中间件Await _next(context)End FunctionEnd Class
End Namespace

2. 主项目扫描逻辑（Program.vb）主项目扫描并注册中间件

Imports Microsoft.AspNetCore.Builder
Imports Microsoft.AspNetCore.Hosting
Imports System.Reflection
Imports System.IOModule ProgramSub Main(args As String())Dim builder = WebApplication.CreateBuilder(args)Dim app = builder.Build()' 扫描bin目录中的所有DLL，自动注册中间件ScanAndRegisterMiddleware(app)app.Run()End Sub' 扫描bin目录并注册符合约定的中间件Private Sub ScanAndRegisterMiddleware(app As WebApplication)Dim binPath = Path.Combine(app.Environment.ContentRootPath, "bin")If Not Directory.Exists(binPath) Then ReturnFor Each dllFile In Directory.GetFiles(binPath, "*.dll", SearchOption.AllDirectories)Try' 加载DLLDim assembly = Assembly.LoadFrom(dllFile)' 查找符合约定的中间件（类名以Middleware结尾，有正确的构造函数和InvokeAsync方法）For Each type In assembly.GetTypes()If type.Name.EndsWith("Middleware") AndAlso type.GetConstructor({GetType(RequestDelegate)}) IsNot Nothing AndAlsotype.GetMethod("InvokeAsync") IsNot Nothing Then' 注册中间件app.Use(Function(context, next)' 反射创建中间件实例并调用Dim middleware = Activator.CreateInstance(type, next)Return CType(type.GetMethod("InvokeAsync").Invoke(middleware, {context}), Task)End Function)End IfNextCatch ex As Exception' 忽略加载失败的DLL（如系统组件）Console.WriteLine($"加载DLL失败：{dllFile}，错误：{ex.Message}")End TryNextEnd Sub
End Module

实现说明

传统ASP.NET方案工作原理：

通过PreApplicationStartMethod特性，ASP.NET在应用启动时会自动执行UploadToolInitializer.Initialize方法
该方法通过HttpApplication.RegisterModule向管道注册自定义模块
模块在BeginRequest事件中拦截特定路径请求并处理
只需将编译后的 DLL 放入项目bin目录，无需修改web.config的handlers或modules