访问ASP.NET Core中的当前HttpContext

Question

我需要HttpContext在静态方法或实用程序服务中访问当前.

使用经典的ASP.NET MVC System.Web,我只是用来HttpContext.Current静态访问上下文.但是我如何在ASP.NET Core中执行此操作？

Answer 1

HttpContext.Current在ASP.NET Core中不再存在但是有一个新的 IHttpContextAccessor,你可以在你的依赖项中注入并用于检索当前HttpContext:

public class MyComponent : IMyComponent
{
    private readonly IHttpContextAccessor _contextAccessor;

    public MyComponent(IHttpContextAccessor contextAccessor)
    {
        _contextAccessor = contextAccessor;
    }

    public string GetDataFromSession()
    {
        return _contextAccessor.HttpContext.Session.GetString(*KEY*);
    }
}

Answer 2

Necromancing.
是的,你可以
为那些迁移大的人提供秘密提示帆船大块(叹息,弗洛伊德滑动)的代码.
下面的方法是一个黑客的邪恶痈,积极参与执行撒旦的快速工作(在.NET Core框架开发人员的眼中),但它的工作原理:

在 public class Startup

添加一个属性

public IConfigurationRoot Configuration { get; }

然后在ConfigureServices中将单个IHttpContextAccessor添加到DI中.

    // This method gets called by the runtime. Use this method to add services to the container.
    public void ConfigureServices(IServiceCollection services)
    {
        services.AddSingleton<Microsoft.AspNetCore.Http.IHttpContextAccessor, Microsoft.AspNetCore.Http.HttpContextAccessor>();

然后在Configure中

    public void Configure(
              IApplicationBuilder app
             ,IHostingEnvironment env
             ,ILoggerFactory loggerFactory
    )
    {

添加DI参数IServiceProvider svp,方法如下:

    public void Configure(
           IApplicationBuilder app
          ,IHostingEnvironment env
          ,ILoggerFactory loggerFactory
          ,IServiceProvider svp)
    {

接下来,为System.Web创建一个替换类:

namespace System.Web
{

    namespace Hosting
    {
        public static class HostingEnvironment 
        {
            public static bool m_IsHosted;

            static HostingEnvironment()
            {
                m_IsHosted = false;
            }

            public static bool IsHosted
            {
                get
                {
                    return m_IsHosted;
                }
            }
        }
    }


    public static class HttpContext
    {
        public static IServiceProvider ServiceProvider;

        static HttpContext()
        { }


        public static Microsoft.AspNetCore.Http.HttpContext Current
        {
            get
            {
                // var factory2 = ServiceProvider.GetService<Microsoft.AspNetCore.Http.IHttpContextAccessor>();
                object factory = ServiceProvider.GetService(typeof(Microsoft.AspNetCore.Http.IHttpContextAccessor));

                // Microsoft.AspNetCore.Http.HttpContextAccessor fac =(Microsoft.AspNetCore.Http.HttpContextAccessor)factory;
                Microsoft.AspNetCore.Http.HttpContext context = ((Microsoft.AspNetCore.Http.HttpContextAccessor)factory).HttpContext;
                // context.Response.WriteAsync("Test");

                return context;
            }
        }


    } // End Class HttpContext 


}

现在在Configure中添加了IServiceProvider svp,将此服务提供者保存到刚创建的虚拟类System.Web.HttpContext(System.Web.HttpContext.ServiceProvider)中的静态变量"ServiceProvider"中

并将HostingEnvironment.IsHosted设置为true

System.Web.Hosting.HostingEnvironment.m_IsHosted = true;

这基本上是System.Web所做的,只是你从未见过它(我猜这个变量被声明为内部而不是公共).

// This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory, IServiceProvider svp)
{
    loggerFactory.AddConsole(Configuration.GetSection("Logging"));
    loggerFactory.AddDebug();

    ServiceProvider = svp;
    System.Web.HttpContext.ServiceProvider = svp;
    System.Web.Hosting.HostingEnvironment.m_IsHosted = true;


    app.UseCookieAuthentication(new CookieAuthenticationOptions()
    {
        AuthenticationScheme = "MyCookieMiddlewareInstance",
        LoginPath = new Microsoft.AspNetCore.Http.PathString("/Account/Unauthorized/"),
        AccessDeniedPath = new Microsoft.AspNetCore.Http.PathString("/Account/Forbidden/"),
        AutomaticAuthenticate = true,
        AutomaticChallenge = true,
        CookieSecure = Microsoft.AspNetCore.Http.CookieSecurePolicy.SameAsRequest

       , CookieHttpOnly=false

    });

就像在ASP.NET Web-Forms中一样,当你尝试访问HttpContext时,你会得到一个NullReference,例如它曾经Application_Start在global.asax中.

我再次强调,这只有在您真正添加时才有效

services.AddSingleton<Microsoft.AspNetCore.Http.IHttpContextAccessor, Microsoft.AspNetCore.Http.HttpContextAccessor>();

就像我写的那样.
欢迎使用DI模式中的ServiceLocator模式;)
有关风险和副作用,请咨询您的住院医生或药剂师 - 或者在github.com/aspnet上研究.NET Core的来源,并进行一些测试.

也许一个更易于维护的方法是添加这个辅助类

namespace System.Web
{

    public static class HttpContext
    {
        private static Microsoft.AspNetCore.Http.IHttpContextAccessor m_httpContextAccessor;


        public static void Configure(Microsoft.AspNetCore.Http.IHttpContextAccessor httpContextAccessor)
        {
            m_httpContextAccessor = httpContextAccessor;
        }


        public static Microsoft.AspNetCore.Http.HttpContext Current
        {
            get
            {
                return m_httpContextAccessor.HttpContext;
            }
        }


    }


}

然后在Startup-> Configure中调用HttpContext.Configure

public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory, IServiceProvider svp)
{
    loggerFactory.AddConsole(Configuration.GetSection("Logging"));
    loggerFactory.AddDebug();


    System.Web.HttpContext.Configure(app.ApplicationServices.
        GetRequiredService<Microsoft.AspNetCore.Http.IHttpContextAccessor>()
    );

Answer 3

只是为了添加其他答案......

在ASP.NET 2.1的核心,还有的AddHttpContextAccessor扩展方法,将注册IHttpContextAccessor与正确的寿命.

Answer 4

我提出的最合法的方法是在静态实现中注入IHttpContextAccessor,如下所示:

public static class HttpHelper
{
     private static IHttpContextAccessor _accessor;
     public static void Configure(IHttpContextAccessor httpContextAccessor)
     {
          _accessor = httpContextAccessor;
     }

     public static HttpContext HttpContext => _accessor.HttpContext;
}

然后在启动配置中分配IHttpContextAccessor应该可以完成这项工作.

HttpHelper.Configure(app.ApplicationServices.GetRequiredService<IHttpContextAccessor>());

我想你还应该注册服务单例:

services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();

Answer 5

根据这篇文章：在 ASP.NET Core 中的框架组件之外访问 HttpContext

namespace System.Web
{
    public static class HttpContext
    {
        private static IHttpContextAccessor _contextAccessor;

        public static Microsoft.AspNetCore.Http.HttpContext Current => _contextAccessor.HttpContext;

        internal static void Configure(IHttpContextAccessor contextAccessor)
        {
            _contextAccessor = contextAccessor;
        }
    }
}

然后：

public static class StaticHttpContextExtensions
{
    public static void AddHttpContextAccessor(this IServiceCollection services)
    {
        services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();
    }

    public static IApplicationBuilder UseStaticHttpContext(this IApplicationBuilder app)
    {
        var httpContextAccessor = app.ApplicationServices.GetRequiredService<IHttpContextAccessor>();
        System.Web.HttpContext.Configure(httpContextAccessor);
        return app;
    }
}

然后：

public class Startup
{
    public void ConfigureServices(IServiceCollection services)
    {
        services.AddHttpContextAccessor();
    }

    public void Configure(IApplicationBuilder app)
    {
        app.UseStaticHttpContext();
        app.UseMvc();
    }
}

你可以这样使用它：

using System.Web;

public class MyService
{
   public void DoWork()
   {
    var context = HttpContext.Current;
    // continue with context instance
   }
}

Answer 6

在启动

services.AddHttpContextAccessor();

在控制器中

public class HomeController : Controller
    {
        private readonly IHttpContextAccessor _context;

        public HomeController(IHttpContextAccessor context)
        {
            _context = context; 
        }
        public IActionResult Index()
        {
           var context = _context.HttpContext.Request.Headers.ToList();
           return View();
        }
   }