Asp.net core .NET核心中间件-在控制器中访问IApplicationBuilder？

我需要访问控制器内的IApplicationBuilder

我尝试过的：-

我已经编写了中间件（app.UseMyMiddleware），如下所示

// This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
    public void Configure(IApplicationBuilder app, IHostingEnvironment env, IHttpContextAccessor httpContextAccessor)
    {
        if (env.IsDevelopment())
        {
            app.UseDeveloperExceptionPage();
        }
        else
        {
            app.UseExceptionHandler("/Home/Error");
            app.UseHsts();
        }

        app.UseHttpsRedirection();
        app.UseStaticFiles();
        app.UseCookiePolicy();
        app.UseMyMiddleware();

        app.UseAuthentication();
        app.UseSession();

        app.UseMvc(routes =>
        {
            routes.MapRoute(
                name: "default",
                template: "{controller=Home}/{action=Index}/{id?}");
        });
    }
public class MyMiddleware
{
    private readonly RequestDelegate _next;

    public MyMiddleware(RequestDelegate next)
    {
        _next = next;
    }

    public async Task Invoke(HttpContext context)
    {
        ///TODO - Pass IApplicationBuilder to HttpContext 
        await _next(context);
    }
}
public static class MiddlewareExtensions
{
    public static IApplicationBuilder UseMyMiddleware(this IApplicationBuilder builder)
    {
        return builder.UseMiddleware<MyMiddleware>();
    }
}

public class HangfireSqlServerStorageExtension : Hangfire.JobStorage
{
    private readonly HangfireSqlServerStorage _hangfireSqlServerStorage = new HangfireSqlServerStorage();

    public HangfireSqlServerStorageExtension(string nameOrConnectionString)
    {
        _hangfireSqlServerStorage.SqlServerStorageOptions = new SqlServerStorageOptions();
        _hangfireSqlServerStorage.SqlServerStorage = new SqlServerStorage(nameOrConnectionString, _hangfireSqlServerStorage.SqlServerStorageOptions);
    }
    public HangfireSqlServerStorageExtension(string nameOrConnectionString, SqlServerStorageOptions options)
    {
        _hangfireSqlServerStorage.SqlServerStorageOptions = options;
        _hangfireSqlServerStorage.SqlServerStorage = new SqlServerStorage(nameOrConnectionString, _hangfireSqlServerStorage.SqlServerStorageOptions);
    }

    public void UpdateConnectionString(string nameOrConnectionString)
    {
        _hangfireSqlServerStorage.SqlServerStorage = new SqlServerStorage(nameOrConnectionString, _hangfireSqlServerStorage.SqlServerStorageOptions);
    }

    public override IStorageConnection GetConnection()
    {
        return _hangfireSqlServerStorage.SqlServerStorage.GetConnection();
    }

    public override IMonitoringApi GetMonitoringApi()
    {
        return _hangfireSqlServerStorage.SqlServerStorage.GetMonitoringApi();
    }
}

public class Startup
{
    ///Other necessary code here
    
    public static HangfireSqlServerStorageExtension HangfireSqlServerStorageExtension { get; private set; }

    public void ConfigureServices(IServiceCollection services)
    {
       ///Other necessary code here
       
        HangfireSqlServerStorageExtension = new HangfireSqlServerStorageExtension("DBConnecttionString"));
        services.AddSingleton<HangfireSqlServerStorageExtension>(HangfireSqlServerStorageExtension);
        services.AddHangfire(configuration => configuration.SetDataCompatibilityLevel(CompatibilityLevel.Version_170));
    }

    // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
    public void Configure(IApplicationBuilder app, IHostingEnvironment env, IHttpContextAccessor httpContextAccessor)
    {
       //Other necessary code here

        app.UseHangfireDashboard("/Dashboard", new DashboardOptions(), HangfireSqlServerStorageExtension);

        //Other necessary code here
    }
}

//此方法由运行时调用。使用此方法配置HTTP请求管道。
公共无效配置（IApplicationBuilder应用程序、IHostingEnvironment环境、IHttpContextAccessor httpContextAccessor）
{
if（env.IsDevelopment（））
{
app.UseDeveloperExceptionPage（）；
}
其他的
{
app.UseExceptionHandler（“/Home/Error”）；
app.UseHsts（）；
}
app.UseHttpsRedirection（）；
app.UseStaticFiles（）；
app.UseCookiePolicy（）；
app.UseMyMiddleware（）；
app.UseAuthentication（）；
app.UseSession（）；
app.UseMvc（路由=>
{
routes.MapRoute(
名称：“默认”，
模板：“{controller=Home}/{action=Index}/{id？}”）；
});
}
公共类中间件
{
private readonly RequestDelegate\u next；
公共MyMiddleware（RequestDelegate下一步）
{
_下一个=下一个；
}
公共异步任务调用（HttpContext上下文）
{
///TODO-将IApplicationBuilder传递给HttpContext
等待下一步（上下文）；
}
}
公共静态类MiddlewareExtensions
{
公共静态IAApplicationBuilder UseMyMiddleware（此IAApplicationBuilder）
{
返回builder.UseMiddleware（）；
}
}

但我不知道如何在Invoke方法中将IAApplicationBuilder传递给HttpContext。所以，我可以在控制器中使用它。 我还提到了以下问题的答案

问题：-

如何将IAApplicationBuilder传递给Invoke方法中的HttpContext，以便在控制器中使用它

除了中间件之外，还有什么更好的方法可以访问控制器内部的IApplicationBuilder吗

---

在完成应用程序构建阶段后（运行

Configure

方法后），您不能访问

iaapplicationbuilder

的任何位置。根本无法注射。 但是，为了在运行时根据请求数据（从

HttpContext

）插入或配置中间件，您可以使用

.UseWhen

。另一个终端中间件是

.MapWhen

，但我认为这不适合您的情况。以下是

.UseWhen

的示例：

public static class MiddlewareExtensions
{
    public static IApplicationBuilder UseMyMiddleware(this IApplicationBuilder builder)
    {
        var allOptions = new [] {"option 1","option 2"};
        foreach(var option in allOptions){
            var currentOption = option;
            builder.UseWhen(context => {
              //suppose you can get the user's selected option from query string
              var selectedOption = context.Request.Query["option_key"];
              return selectedOption == currentOption;
            }, app => {
               //your MyMiddleware is supposed to accept one argument
               app.UseMiddleware<MyMiddleware>(currentOption);
            });
        }
        return builder;
    }
}

---

您必须决定如何从用户处获取所选选项（在上面的示例中，我是从

查询字符串

获取的）。您也可以从

Cookie

获取它（以记住用户的选择），或者从其他来源获取它，例如路由数据、头、表单、请求正文。我认为这是另一个问题，因此，如果您对此有问题，请提出另一个问题。

IApplicationBuilder的设计不是为了按您希望的方式工作。相反，如果您在构建时创建了一些数据，并且希望这些数据可用于中间件，请向服务中添加一个单例，并将该单例注入中间件。

首先感谢@Kingking和@GlennSills提供的解决方案和有价值的评论

我已经解决了这个问题

创建了一个继承自Hangfire.JobStorage的类，如下所示

// This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
    public void Configure(IApplicationBuilder app, IHostingEnvironment env, IHttpContextAccessor httpContextAccessor)
    {
        if (env.IsDevelopment())
        {
            app.UseDeveloperExceptionPage();
        }
        else
        {
            app.UseExceptionHandler("/Home/Error");
            app.UseHsts();
        }

        app.UseHttpsRedirection();
        app.UseStaticFiles();
        app.UseCookiePolicy();
        app.UseMyMiddleware();

        app.UseAuthentication();
        app.UseSession();

        app.UseMvc(routes =>
        {
            routes.MapRoute(
                name: "default",
                template: "{controller=Home}/{action=Index}/{id?}");
        });
    }
public class MyMiddleware
{
    private readonly RequestDelegate _next;

    public MyMiddleware(RequestDelegate next)
    {
        _next = next;
    }

    public async Task Invoke(HttpContext context)
    {
        ///TODO - Pass IApplicationBuilder to HttpContext 
        await _next(context);
    }
}
public static class MiddlewareExtensions
{
    public static IApplicationBuilder UseMyMiddleware(this IApplicationBuilder builder)
    {
        return builder.UseMiddleware<MyMiddleware>();
    }
}

public class HangfireSqlServerStorageExtension : Hangfire.JobStorage
{
    private readonly HangfireSqlServerStorage _hangfireSqlServerStorage = new HangfireSqlServerStorage();

    public HangfireSqlServerStorageExtension(string nameOrConnectionString)
    {
        _hangfireSqlServerStorage.SqlServerStorageOptions = new SqlServerStorageOptions();
        _hangfireSqlServerStorage.SqlServerStorage = new SqlServerStorage(nameOrConnectionString, _hangfireSqlServerStorage.SqlServerStorageOptions);
    }
    public HangfireSqlServerStorageExtension(string nameOrConnectionString, SqlServerStorageOptions options)
    {
        _hangfireSqlServerStorage.SqlServerStorageOptions = options;
        _hangfireSqlServerStorage.SqlServerStorage = new SqlServerStorage(nameOrConnectionString, _hangfireSqlServerStorage.SqlServerStorageOptions);
    }

    public void UpdateConnectionString(string nameOrConnectionString)
    {
        _hangfireSqlServerStorage.SqlServerStorage = new SqlServerStorage(nameOrConnectionString, _hangfireSqlServerStorage.SqlServerStorageOptions);
    }

    public override IStorageConnection GetConnection()
    {
        return _hangfireSqlServerStorage.SqlServerStorage.GetConnection();
    }

    public override IMonitoringApi GetMonitoringApi()
    {
        return _hangfireSqlServerStorage.SqlServerStorage.GetMonitoringApi();
    }
}

public class Startup
{
    ///Other necessary code here
    
    public static HangfireSqlServerStorageExtension HangfireSqlServerStorageExtension { get; private set; }

    public void ConfigureServices(IServiceCollection services)
    {
       ///Other necessary code here
       
        HangfireSqlServerStorageExtension = new HangfireSqlServerStorageExtension("DBConnecttionString"));
        services.AddSingleton<HangfireSqlServerStorageExtension>(HangfireSqlServerStorageExtension);
        services.AddHangfire(configuration => configuration.SetDataCompatibilityLevel(CompatibilityLevel.Version_170));
    }

    // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
    public void Configure(IApplicationBuilder app, IHostingEnvironment env, IHttpContextAccessor httpContextAccessor)
    {
       //Other necessary code here

        app.UseHangfireDashboard("/Dashboard", new DashboardOptions(), HangfireSqlServerStorageExtension);

        //Other necessary code here
    }
}

HangfireSqlServerStorage.cs

在上面的HangfireSqlServerStorageExtension类中使用

public class HangfireSqlServerStorage
{
    public SqlServerStorage SqlServerStorage { get; set; }
    public SqlServerStorageOptions SqlServerStorageOptions { get; set; }
}

Startup.cs

在启动文件中，为HangfireSqlServerStorageExtension实例添加singleton服务，并按如下方式配置hangfire仪表板

// This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
    public void Configure(IApplicationBuilder app, IHostingEnvironment env, IHttpContextAccessor httpContextAccessor)
    {
        if (env.IsDevelopment())
        {
            app.UseDeveloperExceptionPage();
        }
        else
        {
            app.UseExceptionHandler("/Home/Error");
            app.UseHsts();
        }

        app.UseHttpsRedirection();
        app.UseStaticFiles();
        app.UseCookiePolicy();
        app.UseMyMiddleware();

        app.UseAuthentication();
        app.UseSession();

        app.UseMvc(routes =>
        {
            routes.MapRoute(
                name: "default",
                template: "{controller=Home}/{action=Index}/{id?}");
        });
    }
public class MyMiddleware
{
    private readonly RequestDelegate _next;

    public MyMiddleware(RequestDelegate next)
    {
        _next = next;
    }

    public async Task Invoke(HttpContext context)
    {
        ///TODO - Pass IApplicationBuilder to HttpContext 
        await _next(context);
    }
}
public static class MiddlewareExtensions
{
    public static IApplicationBuilder UseMyMiddleware(this IApplicationBuilder builder)
    {
        return builder.UseMiddleware<MyMiddleware>();
    }
}

public class HangfireSqlServerStorageExtension : Hangfire.JobStorage
{
    private readonly HangfireSqlServerStorage _hangfireSqlServerStorage = new HangfireSqlServerStorage();

    public HangfireSqlServerStorageExtension(string nameOrConnectionString)
    {
        _hangfireSqlServerStorage.SqlServerStorageOptions = new SqlServerStorageOptions();
        _hangfireSqlServerStorage.SqlServerStorage = new SqlServerStorage(nameOrConnectionString, _hangfireSqlServerStorage.SqlServerStorageOptions);
    }
    public HangfireSqlServerStorageExtension(string nameOrConnectionString, SqlServerStorageOptions options)
    {
        _hangfireSqlServerStorage.SqlServerStorageOptions = options;
        _hangfireSqlServerStorage.SqlServerStorage = new SqlServerStorage(nameOrConnectionString, _hangfireSqlServerStorage.SqlServerStorageOptions);
    }

    public void UpdateConnectionString(string nameOrConnectionString)
    {
        _hangfireSqlServerStorage.SqlServerStorage = new SqlServerStorage(nameOrConnectionString, _hangfireSqlServerStorage.SqlServerStorageOptions);
    }

    public override IStorageConnection GetConnection()
    {
        return _hangfireSqlServerStorage.SqlServerStorage.GetConnection();
    }

    public override IMonitoringApi GetMonitoringApi()
    {
        return _hangfireSqlServerStorage.SqlServerStorage.GetMonitoringApi();
    }
}

public class Startup
{
    ///Other necessary code here
    
    public static HangfireSqlServerStorageExtension HangfireSqlServerStorageExtension { get; private set; }

    public void ConfigureServices(IServiceCollection services)
    {
       ///Other necessary code here
       
        HangfireSqlServerStorageExtension = new HangfireSqlServerStorageExtension("DBConnecttionString"));
        services.AddSingleton<HangfireSqlServerStorageExtension>(HangfireSqlServerStorageExtension);
        services.AddHangfire(configuration => configuration.SetDataCompatibilityLevel(CompatibilityLevel.Version_170));
    }

    // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
    public void Configure(IApplicationBuilder app, IHostingEnvironment env, IHttpContextAccessor httpContextAccessor)
    {
       //Other necessary code here

        app.UseHangfireDashboard("/Dashboard", new DashboardOptions(), HangfireSqlServerStorageExtension);

        //Other necessary code here
    }
}

---

iaapplicationbuilder

设计用于在启动时构建应用程序，运行一次，而不是在以后运行时运行。因此，我认为它不能为您提供任何运行时服务或API，您想要它做什么？这比如何使其可用更重要。@KingKing我想使用此IApplicationBuilder在控制器中配置Hangfire。您可以参考问题了解更多详细信息您以后无法访问

iaapplicationbuilder

，但您可以在运行时使用

useawhen

插入中间件。但是，筛选条件不能利用您的

MVC模型绑定

，因为您只有

HttpContext

作为输入，您自己从原始源（查询字符串、路由数据、标题、表单、请求正文）提取请求数据。你可以通过某种方式实现一个设置，记住或发送每个请求的所选选项）。@KingKing你能给我一个例子吗？我该怎么做？@KingKing谢谢！对于您的努力，我会检查并让您知道。谢谢您提供的信息。有没有其他办法来解决这个问题？我尝试了以下答案中提供的KingKing方法，但使用该方法，我无法根据“builder.UseWhen”条件更改“app.UseHangfireDashboard”的配置。（它仅在应用程序启动时配置）。查看一个关于如何在控制器中使用IApplicationBuilder的示例将非常有用。如果您告诉我，我可能可以为您提供一个解决方案。@开发者我很确定您不知道如何应用我的解决方案，

。使用when

是您可以尝试的唯一选项。但看起来你不需要解决它，好吧。许多用户通过来回响应来获得最终解决方案，但您只是保持沉默，这样就没有机会让其他人提供帮助。“那只是你的选择。”金金对迟迟不答复深表歉意。我已经使用了您的解决方案，但使用该解决方案，我无法根据条件（使用.UseWhen）更改hangfire配置（表示hangfire连接字符串）。现在，我补充了我的答案。感谢您的努力，很抱歉延迟回复。