我发现了这个链接,但它似乎已经过时并在错误后抛出错误：Getting absolute URLs using ASP.NET Core MVC 6
在我的Startup.cs中,我在ConfigureServices下：
services.AddSingleton<IHttpContextAccessor,HttpContextAccessor>();
在我的Startup.cs中我有配置：
IHttpContextAccessor httpContextAccessor = app.ApplicationServices.GetrequiredService<IHttpContextAccessor>(); Extensions.Context.Configure(httpContextAccessor);
我有以下课程：
using Microsoft.AspNetCore.Http;
using System;
namespace Framework.Extensions
{
public static class Context
{
private static IHttpContextAccessor HttpContextAccessor;
public static void Configure(IHttpContextAccessor httpContextAccessor)
{
HttpContextAccessor = httpContextAccessor;
}
private static HttpContext GetCurrentContext()
{
return HttpContextAccessor.HttpContext;
}
public static HttpContext Current = GetCurrentContext();
private static Uri GetAbsoluteUri()
{
UriBuilder uriBuilder = new UriBuilder();
uriBuilder.Scheme = GetCurrentContext().Request.Scheme;
uriBuilder.Host = GetCurrentContext().Request.Host.ToString();
uriBuilder.Path = GetCurrentContext().Request.Path.ToString();
uriBuilder.Query = GetCurrentContext().Request.QueryString.ToString();
return uriBuilder.Uri;
}
public static Uri AbsoluteUri = GetAbsoluteUri();
public static string Url = GetAbsoluteUri().ToString();
public static string AbsolutePath = GetAbsoluteUri().AbsolutePath;
}
}
我得到以下异常：
System.TypeInitializationException was unhandled by user code
HResult=-2146233036 Message=The type initializer for
‘Framework.Extensions.Context’ threw an exception.
TypeName=Framework.Extensions.Context InnerException:
HResult=-2147467261
Message=Object reference not set to an instance of an object.
Source=www
StackTrace:
at Framework.Extensions.Context.GetCurrentContext() in E:\Websites\Stage\www\Extensions\Context.cs:line 16
at Framework.Extensions.Context..cctor() in E:\Websites\Stage\www\Extensions\Context.cs:line 18
InnerException:
解决方法
您无法将上下文存储在静态字段中,因为该上下文仅在提供特定请求时才有意义.通常,您将把访问器保留在静态字段中,并在每次调用助手时使用它.
>更糟糕的是,您使用带有初始化程序的静态字段,这些字段在第一次使用该类时执行.这意味着它们在您调用Configure方法之前执行,因此将不会配置IHttpContextAccessor,您将获得这些空引用.
写下你想要的东西很简单：
public static class Context
{
private static IHttpContextAccessor HttpContextAccessor;
public static void Configure(IHttpContextAccessor httpContextAccessor)
{
HttpContextAccessor = httpContextAccessor;
}
private static Uri GetAbsoluteUri()
{
var request = HttpContextAccessor.HttpContext.Request;
UriBuilder uriBuilder = new UriBuilder();
uriBuilder.Scheme = request.Scheme;
uriBuilder.Host = request.Host.Host;
uriBuilder.Path = request.Path.ToString();
uriBuilder.Query = request.QueryString.ToString();
return uriBuilder.Uri;
}
// Similar methods for Url/AbsolutePath which internally call GetAbsoluteUri
public static string GetAbsoluteUrl() { }
public static string GetAbsolutePath() { }
}
还有一件事要记住：
>在最初的问题中,帮助程序是作为静态类创建的,因为它们是作为扩展方法创建的.如果您不使用扩展方法,则不必强制使用静态类.
