ASP.NET Core 中 HttpContext 详解与使用

阳光穿透心脏的1/2处 2022-09-16 15:16 384阅读 0赞

# 一、“传导体” HttpContext #

## 1.1、了解HttpContext是做什么的 ##

**①内网访问程序**

![181f8e58ddd74daf1969e5f1bfa4da78.png][]

②**反向代理访问程序**

![4996a311030e479c0625f90b881e3a76.png][]

**ASP.NET Core** 程序中，**Kestrel** 是一个基于 **libuv** 的跨平台 **ASP.NET Core web** 服务器。

[ASP.NETCore的Kestrel服务器][ASP.NETCore_Kestrel]

我们可以理解成，外部访问我们的程序，通过 Http 或者 Https 访问，例如 https://localhost:44337/Home/Index，需要通过一个网址，来寻向访问特定的页面。

访问页面时，会产生 Cookie、Seesion、提交表单、上传数据、身份认证等，外部与应用程序之间传导的导体就是 **HttpContext**。

总之，客户端跟 Web应用程序交互 是通过 **HttpContext** 传导的。

## 1.2、原理 ##

**ASP.NET Core** 本质是一个控制台程序！**ASP.NET Core** 程序并不直接监听请求，而是通过依赖 **HTTP Server** ，来实现把各自请求转发到应用程序中。这个被转发的请求相当于我们日常浏览网页、上传文件、提交表单等的网络请求，这些请求会被包装，然后组合到 **HttpContext** 中。

就好像顾客到餐厅吃饭

1.  需要先点菜、提出服务要求
2.  服务员把你的菜单、需求送到厨房
3.  厨师在加工好食品
4.  服务员再把食品递给你

**HttpContext** 相当于这个服务员，她在前、后传递信息。

# 二、操作 HttpContext 前期准备 #

一般来说，我们主要写好Web程序，而无需理会 数据是怎么传导的。就好像两台电脑能够发送资料，我们用不着知道他们是通过无线Wifi、光纤还是铜线电缆传输的。先简单操作 **HttpContext** 了解下。后面接着解析这个对象。

①新建一个【asp.net core web应用(模型-视图-控制器)】项目

![watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBAeGlhb2NoZW5YSUhVQQ_size_20_color_FFFFFF_t_70_g_se_x_16][]

②打开 **Startup.cs** ，在 **ConfigureServices** 中加上

services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();

![watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBAeGlhb2NoZW5YSUhVQQ_size_20_color_FFFFFF_t_70_g_se_x_16 1][]

③打开 **HomeController.cs** ，添加【**using Microsoft.AspNetCore.Http;**】引用，修改**HomeController** 类替换成以下代码。

public class HomeController : Controller
        {
            private IHttpContextAccessor _accessor;
            public HomeController(IHttpContextAccessor accessor)
            {
                _accessor = accessor;
            }
    
            [HttpGet]
            public IActionResult Index(int? id)
            {
                var httpcontext = _accessor.HttpContext;
    
                return View(httpcontext);
            }
    
    
        }//Class_end

④打开 **Views/Home** 目录，删除 **Index.cshtml** 外的其它视图；在把 **Index.cshtml** 的代码改成

@model Microsoft.AspNetCore.Http.HttpContext
    @{
        Layout = null;
    }

目前为止准备工作已经完成。

**以上代码的作用：【是把 HttpContext 对象 传递到 视图 中，直接在视图中使用。这样我们在理解时，只需在视图测试即可】。**

# 二、HttpContext 类型的属性和方法 #

在 ASP.NET Core 中，**系统为每一个请求分配一个线程，HttpContext 针对的就是一个线程**。所以它的类、方法、属性等，都是针对当前请求起作用。

### Properties(特性) ###

<table> 
 <tbody> 
  <tr> 
   <td><a href="https://docs.microsoft.com/zh-cn/dotnet/api/microsoft.aspnetcore.http.httpcontext.authentication?view=aspnetcore-2.1#Microsoft_AspNetCore_Http_HttpContext_Authentication" title="Authentication" rel="nofollow">Authentication</a>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;</td> 
   <td> <p>这个已经用不到了，这里只是列一下表。</p> <p>用于身份认证(ASP.NET中用到)，官方不建议在ASP.NT Core中使用。替代方案 Microsoft.AspNetCore.Authentication.AuthenticationHttpContextExtensions</p> </td> 
  </tr> 
  <tr> 
   <td><a href="https://docs.microsoft.com/zh-cn/dotnet/api/microsoft.aspnetcore.http.httpcontext.connection?view=aspnetcore-2.1#Microsoft_AspNetCore_Http_HttpContext_Connection" title="Connection" rel="nofollow">Connection</a></td> 
   <td> <p>获取有关此请求的基础连接的信息</p> </td> 
  </tr> 
  <tr> 
   <td><a href="https://docs.microsoft.com/zh-cn/dotnet/api/microsoft.aspnetcore.http.httpcontext.features?view=aspnetcore-2.1#Microsoft_AspNetCore_Http_HttpContext_Features" title="Features" rel="nofollow">Features</a></td> 
   <td> <p>获取此请求上可用的服务器和中间件提供的HTTP特性的集合</p> </td> 
  </tr> 
  <tr> 
   <td><a href="https://docs.microsoft.com/zh-cn/dotnet/api/microsoft.aspnetcore.http.httpcontext.items?view=aspnetcore-2.1#Microsoft_AspNetCore_Http_HttpContext_Items" title="Items" rel="nofollow">Items</a></td> 
   <td> <p>获取或设置可用于在该请求范围内共享数据的键/值集合</p> </td> 
  </tr> 
  <tr> 
   <td><a href="https://docs.microsoft.com/zh-cn/dotnet/api/microsoft.aspnetcore.http.httpcontext.request?view=aspnetcore-2.1#Microsoft_AspNetCore_Http_HttpContext_Request" title="Request" rel="nofollow">Request</a></td> 
   <td> <p>请求</p> </td> 
  </tr> 
  <tr> 
   <td><a href="https://docs.microsoft.com/zh-cn/dotnet/api/microsoft.aspnetcore.http.httpcontext.requestaborted?view=aspnetcore-2.1#Microsoft_AspNetCore_Http_HttpContext_RequestAborted" title="RequestAborted" rel="nofollow">RequestAborted</a></td> 
   <td> <p>通知此请求基础的连接何时中止，因此请求操作应取消</p> </td> 
  </tr> 
  <tr> 
   <td><a href="https://docs.microsoft.com/zh-cn/dotnet/api/microsoft.aspnetcore.http.httpcontext.requestservices?view=aspnetcore-2.1#Microsoft_AspNetCore_Http_HttpContext_RequestServices" title="RequestServices" rel="nofollow">RequestServices</a></td> 
   <td> <p>获取或设置 IServiceProvider 集合，提供访问的请求的服务容器</p> </td> 
  </tr> 
  <tr> 
   <td><a href="https://docs.microsoft.com/zh-cn/dotnet/api/microsoft.aspnetcore.http.httpcontext.response?view=aspnetcore-2.1#Microsoft_AspNetCore_Http_HttpContext_Response" title="Response" rel="nofollow">Response</a></td> 
   <td> <p>响应</p> </td> 
  </tr> 
  <tr> 
   <td><a href="https://docs.microsoft.com/zh-cn/dotnet/api/microsoft.aspnetcore.http.httpcontext.session?view=aspnetcore-2.1#Microsoft_AspNetCore_Http_HttpContext_Session" title="Session" rel="nofollow">Session</a></td> 
   <td> <p>获取或设置用于管理此请求的用户会话数据的对象</p> </td> 
  </tr> 
  <tr> 
   <td><a href="https://docs.microsoft.com/zh-cn/dotnet/api/microsoft.aspnetcore.http.httpcontext.traceidentifier?view=aspnetcore-2.1#Microsoft_AspNetCore_Http_HttpContext_TraceIdentifier" title="TraceIdentifier" rel="nofollow">TraceIdentifier</a></td> 
   <td> <p>获取或设置用于在跟踪日志中表示此请求的唯一标识符</p> </td> 
  </tr> 
  <tr> 
   <td><a href="https://docs.microsoft.com/zh-cn/dotnet/api/microsoft.aspnetcore.http.httpcontext.user?view=aspnetcore-2.1#Microsoft_AspNetCore_Http_HttpContext_User" title="User" rel="nofollow">User</a></td> 
   <td> <p>获取或设置此请求的用户</p> </td> 
  </tr> 
  <tr> 
   <td><a href="https://docs.microsoft.com/zh-cn/dotnet/api/microsoft.aspnetcore.http.httpcontext.websockets?view=aspnetcore-2.1#Microsoft_AspNetCore_Http_HttpContext_WebSockets" title="WebSockets" rel="nofollow">WebSockets</a></td> 
   <td> <p>获取一个对象，该对象管理此请求的WebSu套连接的建立</p> </td> 
  </tr> 
 </tbody> 
</table>

# 三、HttpContext 对象实践与测试 #

## 3.1、Request ##

**Request 是 客户端向Web发送请求**，用于获取用户请求的对象，**浏览器向Web程序提交表单、访问的URL、URL中包含的查询字符串、报文请求头等等。**

<table> 
 <tbody> 
  <tr> 
   <td><a href="https://docs.microsoft.com/zh-cn/dotnet/api/microsoft.aspnetcore.http.httprequest.body?view=aspnetcore-2.1#Microsoft_AspNetCore_Http_HttpRequest_Body" title="Body" rel="nofollow">Body</a></td> 
   <td> <p>获取或设置&nbsp;RequestBody 流</p> </td> 
  </tr> 
  <tr> 
   <td><a href="https://docs.microsoft.com/zh-cn/dotnet/api/microsoft.aspnetcore.http.httprequest.contentlength?view=aspnetcore-2.1#Microsoft_AspNetCore_Http_HttpRequest_ContentLength" title="ContentLength" rel="nofollow">ContentLength</a></td> 
   <td> <p>获取或设置 Content-Length&nbsp;头</p> </td> 
  </tr> 
  <tr> 
   <td><a href="https://docs.microsoft.com/zh-cn/dotnet/api/microsoft.aspnetcore.http.httprequest.contenttype?view=aspnetcore-2.1#Microsoft_AspNetCore_Http_HttpRequest_ContentType" title="ContentType" rel="nofollow">ContentType</a></td> 
   <td> <p>获取或设置Content-Type 头</p> </td> 
  </tr> 
  <tr> 
   <td><a href="https://docs.microsoft.com/zh-cn/dotnet/api/microsoft.aspnetcore.http.httprequest.cookies?view=aspnetcore-2.1#Microsoft_AspNetCore_Http_HttpRequest_Cookies" title="Cookies" rel="nofollow">Cookies</a></td> 
   <td> <p>获取或设置 Cookies</p> </td> 
  </tr> 
  <tr> 
   <td><a href="https://docs.microsoft.com/zh-cn/dotnet/api/microsoft.aspnetcore.http.httprequest.form?view=aspnetcore-2.1#Microsoft_AspNetCore_Http_HttpRequest_Form" title="Form" rel="nofollow">Form</a></td> 
   <td> <p>获取或设置 表单内容</p> </td> 
  </tr> 
  <tr> 
   <td><a href="https://docs.microsoft.com/zh-cn/dotnet/api/microsoft.aspnetcore.http.httprequest.hasformcontenttype?view=aspnetcore-2.1#Microsoft_AspNetCore_Http_HttpRequest_HasFormContentType" title="HasFormContentType" rel="nofollow">HasFormContentType</a>&nbsp; &nbsp; &nbsp;</td> 
   <td> <p>Checks the Content-Type header for form types.</p> </td> 
  </tr> 
  <tr> 
   <td><a href="https://docs.microsoft.com/zh-cn/dotnet/api/microsoft.aspnetcore.http.httprequest.headers?view=aspnetcore-2.1#Microsoft_AspNetCore_Http_HttpRequest_Headers" title="Headers" rel="nofollow">Headers</a></td> 
   <td> <p>Gets the request headers.</p> </td> 
  </tr> 
  <tr> 
   <td><a href="https://docs.microsoft.com/zh-cn/dotnet/api/microsoft.aspnetcore.http.httprequest.host?view=aspnetcore-2.1#Microsoft_AspNetCore_Http_HttpRequest_Host" title="Host" rel="nofollow">Host</a></td> 
   <td> <p>获取或设置主机头。可以包括端口</p> </td> 
  </tr> 
  <tr> 
   <td><a href="https://docs.microsoft.com/zh-cn/dotnet/api/microsoft.aspnetcore.http.httprequest.httpcontext?view=aspnetcore-2.1#Microsoft_AspNetCore_Http_HttpRequest_HttpContext" title="HttpContext" rel="nofollow">HttpContext</a></td> 
   <td> <p>获取或设置请求上下文</p> </td> 
  </tr> 
  <tr> 
   <td><a href="https://docs.microsoft.com/zh-cn/dotnet/api/microsoft.aspnetcore.http.httprequest.ishttps?view=aspnetcore-2.1#Microsoft_AspNetCore_Http_HttpRequest_IsHttps" title="IsHttps" rel="nofollow">IsHttps</a></td> 
   <td> <p>检测当前是否HTTPS连接</p> </td> 
  </tr> 
  <tr> 
   <td><a href="https://docs.microsoft.com/zh-cn/dotnet/api/microsoft.aspnetcore.http.httprequest.method?view=aspnetcore-2.1#Microsoft_AspNetCore_Http_HttpRequest_Method" title="Method" rel="nofollow">Method</a></td> 
   <td> <p>获取或设置HTTP方法</p> </td> 
  </tr> 
  <tr> 
   <td><a href="https://docs.microsoft.com/zh-cn/dotnet/api/microsoft.aspnetcore.http.httprequest.path?view=aspnetcore-2.1#Microsoft_AspNetCore_Http_HttpRequest_Path" title="Path" rel="nofollow">Path</a></td> 
   <td> <p>获取或设置当前请求的路径,即URL</p> </td> 
  </tr> 
  <tr> 
   <td><a href="https://docs.microsoft.com/zh-cn/dotnet/api/microsoft.aspnetcore.http.httprequest.pathbase?view=aspnetcore-2.1#Microsoft_AspNetCore_Http_HttpRequest_PathBase" title="PathBase" rel="nofollow">PathBase</a></td> 
   <td> <p>获取或设置 RequestPathBase，就是URL前面那一段，如https://docs.microsoft.com</p> </td> 
  </tr> 
  <tr> 
   <td><a href="https://docs.microsoft.com/zh-cn/dotnet/api/microsoft.aspnetcore.http.httprequest.protocol?view=aspnetcore-2.1#Microsoft_AspNetCore_Http_HttpRequest_Protocol" title="Protocol" rel="nofollow">Protocol</a></td> 
   <td> <p>Gets or sets the RequestProtocol.</p> </td> 
  </tr> 
  <tr> 
   <td><a href="https://docs.microsoft.com/zh-cn/dotnet/api/microsoft.aspnetcore.http.httprequest.query?view=aspnetcore-2.1#Microsoft_AspNetCore_Http_HttpRequest_Query" title="Query" rel="nofollow">Query</a></td> 
   <td> <p>查询字符串的集合</p> </td> 
  </tr> 
  <tr> 
   <td><a href="https://docs.microsoft.com/zh-cn/dotnet/api/microsoft.aspnetcore.http.httprequest.querystring?view=aspnetcore-2.1#Microsoft_AspNetCore_Http_HttpRequest_QueryString" title="QueryString" rel="nofollow">QueryString</a></td> 
   <td> <p>获取或设置用于在Request.Query中创建查询集合的原始查询字符串</p> </td> 
  </tr> 
  <tr> 
   <td><a href="https://docs.microsoft.com/zh-cn/dotnet/api/microsoft.aspnetcore.http.httprequest.scheme?view=aspnetcore-2.1#Microsoft_AspNetCore_Http_HttpRequest_Scheme" title="Scheme" rel="nofollow">Scheme</a></td> 
   <td> <p>获取或设置HTTP请求方案</p> </td> 
  </tr> 
 </tbody> 
</table>

**Request请求示例**

①打开 Index.Cshtml ，修改为如下内容：

@model Microsoft.AspNetCore.Http.HttpContext
    @{
        Layout = null;
    }
    
    <table>
        <tr>
            <td>RequestBody流</td>
            <td> @Model.Request.Body</td>
        </tr>
        <tr>
            <td>Content-Length头</td>
            <td>@Model.Request.ContentLength</td>
        </tr>
        <tr>
            <td>Content-Type头</td>
            <td> @Model.Request.ContentType</td>
        <tr>
            <td>Cookies </td>
            <td>@Model.Request.Cookies</td>
        </tr>
        <tr>
            <td>IsHttps</td>
            <td>@Model.Request.IsHttps</td>
        </tr>
        <tr>
            <td>Host </td>
            <td>@Model.Request.Host</td>
        </tr>
    
    </table>

②运行效果如下：

![watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBAeGlhb2NoZW5YSUhVQQ_size_16_color_FFFFFF_t_70_g_se_x_16][]

在浏览器 F12 后，可以看到控制台的内容。请查看 下图的 1、3部分

![watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBAeGlhb2NoZW5YSUhVQQ_size_19_color_FFFFFF_t_70_g_se_x_16][]

Request 的其它使用方法，就不再赘述，你可以在视图中【@Model.Request】 加上需要测试的属性即可。【推荐别人关于 Request 的文章 [HttpRequest 类][HttpRequest]】

## 3.2、Response ##

Request 是 客户端向 Web 发送请求，**而 Response 则是 Web 响应 客户端 的请求**。**使用Response可以直接影响服务器响应**，设置响应内容、响应类型(发送网页、文件、图片等)、视图响应前重定向。

**1、Response 应该在控制器中使用**

<table> 
 <tbody> 
  <tr> 
   <td><a href="https://docs.microsoft.com/zh-cn/dotnet/api/microsoft.aspnetcore.http.httpresponse.body?view=aspnetcore-2.1#Microsoft_AspNetCore_Http_HttpResponse_Body" title="Body" rel="nofollow">Body</a></td> 
   <td> <p>获取或设置响应体流</p> </td> 
  </tr> 
  <tr> 
   <td><a href="https://docs.microsoft.com/zh-cn/dotnet/api/microsoft.aspnetcore.http.httpresponse.contentlength?view=aspnetcore-2.1#Microsoft_AspNetCore_Http_HttpResponse_ContentLength" title="ContentLength" rel="nofollow">ContentLength</a>&nbsp; &nbsp; &nbsp;</td> 
   <td> <p>Gets or sets the value for the&nbsp;<code>Content-Type</code>&nbsp;response header.</p> </td> 
  </tr> 
  <tr> 
   <td><a href="https://docs.microsoft.com/zh-cn/dotnet/api/microsoft.aspnetcore.http.httpresponse.contenttype?view=aspnetcore-2.1#Microsoft_AspNetCore_Http_HttpResponse_ContentType" title="ContentType" rel="nofollow">ContentType</a></td> 
   <td> <p>获取或设置内容类型响应标头的值</p> </td> 
  </tr> 
  <tr> 
   <td><a href="https://docs.microsoft.com/zh-cn/dotnet/api/microsoft.aspnetcore.http.httpresponse.cookies?view=aspnetcore-2.1#Microsoft_AspNetCore_Http_HttpResponse_Cookies" title="Cookies" rel="nofollow">Cookies</a></td> 
   <td> <p>获取一个对象，该对象可用于管理此响应的Cookie</p> </td> 
  </tr> 
  <tr> 
   <td><a href="https://docs.microsoft.com/zh-cn/dotnet/api/microsoft.aspnetcore.http.httpresponse.hasstarted?view=aspnetcore-2.1#Microsoft_AspNetCore_Http_HttpResponse_HasStarted" title="HasStarted" rel="nofollow">HasStarted</a></td> 
   <td> <p>Gets a value indicating whether response headers have been sent to the client.</p> </td> 
  </tr> 
  <tr> 
   <td><a href="https://docs.microsoft.com/zh-cn/dotnet/api/microsoft.aspnetcore.http.httpresponse.headers?view=aspnetcore-2.1#Microsoft_AspNetCore_Http_HttpResponse_Headers" title="Headers" rel="nofollow">Headers</a></td> 
   <td> <p>Gets the response headers.</p> </td> 
  </tr> 
  <tr> 
   <td><a href="https://docs.microsoft.com/zh-cn/dotnet/api/microsoft.aspnetcore.http.httpresponse.httpcontext?view=aspnetcore-2.1#Microsoft_AspNetCore_Http_HttpResponse_HttpContext" title="HttpContext" rel="nofollow">HttpContext</a></td> 
   <td> <p>Gets the&nbsp;<a href="https://docs.microsoft.com/zh-cn/dotnet/api/microsoft.aspnetcore.http.httpresponse.httpcontext?view=aspnetcore-2.1#Microsoft_AspNetCore_Http_HttpResponse_HttpContext" title="HttpContext" rel="nofollow">HttpContext</a>&nbsp;for this response.</p> </td> 
  </tr> 
  <tr> 
   <td><a href="https://docs.microsoft.com/zh-cn/dotnet/api/microsoft.aspnetcore.http.httpresponse.statuscode?view=aspnetcore-2.1#Microsoft_AspNetCore_Http_HttpResponse_StatusCode" title="StatusCode" rel="nofollow">StatusCode</a></td> 
   <td> <p>Gets or sets the HTTP response code.</p> </td> 
  </tr> 
 </tbody> 
</table>

**2、Response 的方法**

<table> 
 <tbody> 
  <tr> 
   <td>　　　　&nbsp;<a href="https://docs.microsoft.com/zh-cn/dotnet/api/microsoft.aspnetcore.http.httpresponse.oncompleted?view=aspnetcore-2.1#Microsoft_AspNetCore_Http_HttpResponse_OnCompleted_System_Func_System_Threading_Tasks_Task__" title="OnCompleted(Func<Task>)" rel="nofollow">OnCompleted(Func&lt;Task&gt;)</a>&nbsp;</td> 
   <td> <p>在响应已发送到客户端之后添加要调用的委托</p> </td> 
  </tr> 
  <tr> 
   <td>　　　　&nbsp;<a href="https://docs.microsoft.com/zh-cn/dotnet/api/microsoft.aspnetcore.http.httpresponse.oncompleted?view=aspnetcore-2.1#Microsoft_AspNetCore_Http_HttpResponse_OnCompleted_System_Func_System_Object_System_Threading_Tasks_Task__System_Object_" title="OnCompleted(Func<Object,Task>, Object)" rel="nofollow">OnCompleted(Func&lt;Object,Task&gt;, Object)</a>&nbsp;　　　　&nbsp; &nbsp; &nbsp;</td> 
   <td> <p>响应已发送到客户端之后添加要调用的委托</p> </td> 
  </tr> 
  <tr> 
   <td>　　　　&nbsp;<a href="https://docs.microsoft.com/zh-cn/dotnet/api/microsoft.aspnetcore.http.httpresponse.onstarting?view=aspnetcore-2.1#Microsoft_AspNetCore_Http_HttpResponse_OnStarting_System_Func_System_Threading_Tasks_Task__" title="OnStarting(Func<Task>)" rel="nofollow">OnStarting(Func&lt;Task&gt;)</a></td> 
   <td> <p>在响应头将被发送到客户端之前添加要调用的委托</p> </td> 
  </tr> 
  <tr> 
   <td>　　　　&nbsp;<a href="https://docs.microsoft.com/zh-cn/dotnet/api/microsoft.aspnetcore.http.httpresponse.onstarting?view=aspnetcore-2.1#Microsoft_AspNetCore_Http_HttpResponse_OnStarting_System_Func_System_Object_System_Threading_Tasks_Task__System_Object_" title="OnStarting(Func<Object,Task>, Object)" rel="nofollow">OnStarting(Func&lt;Object,Task&gt;, Object)</a></td> 
   <td> <p>在响应头将被发送到客户端之前添加要调用的委托</p> </td> 
  </tr> 
  <tr> 
   <td>　　　　&nbsp;<a href="https://docs.microsoft.com/zh-cn/dotnet/api/microsoft.aspnetcore.http.httpresponse.redirect?view=aspnetcore-2.1#Microsoft_AspNetCore_Http_HttpResponse_Redirect_System_String_" title="Redirect(String)" rel="nofollow">Redirect(String)</a></td> 
   <td> <p>向客户端返回一个临时重定向响应（HTTP 302）</p> </td> 
  </tr> 
  <tr> 
   <td>　　　　&nbsp;<a href="https://docs.microsoft.com/zh-cn/dotnet/api/microsoft.aspnetcore.http.httpresponse.redirect?view=aspnetcore-2.1#Microsoft_AspNetCore_Http_HttpResponse_Redirect_System_String_System_Boolean_" title="Redirect(String, Boolean)" rel="nofollow">Redirect(String, Boolean)</a></td> 
   <td> <p>向客户端返回重定向响应（HTTP 301或HTTP 302）</p> </td> 
  </tr> 
  <tr> 
   <td>　　　　&nbsp;<a href="https://docs.microsoft.com/zh-cn/dotnet/api/microsoft.aspnetcore.http.httpresponse.registerfordispose?view=aspnetcore-2.1#Microsoft_AspNetCore_Http_HttpResponse_RegisterForDispose_System_IDisposable_" title="RegisterForDispose(IDisposable)" rel="nofollow">RegisterForDispose(IDisposable)</a></td> 
   <td> <p>处置（不可分）在请求完成处理后，注册主机处理的对象&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;</p> </td> 
  </tr> 
 </tbody> 
</table>

**3、Response 拓展方法**

<table> 
 <tbody> 
  <tr> 
   <td colspan="2"><a href="https://docs.microsoft.com/zh-cn/dotnet/api/microsoft.aspnetcore.http.headerdictionarytypeextensions.gettypedheaders?view=aspnetcore-2.1#Microsoft_AspNetCore_Http_HeaderDictionaryTypeExtensions_GetTypedHeaders_Microsoft_AspNetCore_Http_HttpResponse_" title="GetTypedHeaders(HttpResponse)" rel="nofollow">GetTypedHeaders(HttpResponse)</a></td> 
  </tr> 
  <tr> 
   <td><a href="https://docs.microsoft.com/zh-cn/dotnet/api/microsoft.aspnetcore.http.httpresponsewritingextensions.writeasync?view=aspnetcore-2.1#Microsoft_AspNetCore_Http_HttpResponseWritingExtensions_WriteAsync_Microsoft_AspNetCore_Http_HttpResponse_System_String_System_Text_Encoding_System_Threading_CancellationToken_" title="WriteAsync(HttpResponse, String, Encoding, CancellationToken)" rel="nofollow">WriteAsync(HttpResponse, String, Encoding, CancellationToken)</a></td> 
   <td> <p>取消令牌使用给定的编码将给定文本写入响应体</p> </td> 
  </tr> 
  <tr> 
   <td><a href="https://docs.microsoft.com/zh-cn/dotnet/api/microsoft.aspnetcore.http.httpresponsewritingextensions.writeasync?view=aspnetcore-2.1#Microsoft_AspNetCore_Http_HttpResponseWritingExtensions_WriteAsync_Microsoft_AspNetCore_Http_HttpResponse_System_String_System_Threading_CancellationToken_" title="WriteAsync(HttpResponse, String, CancellationToken)" rel="nofollow">WriteAsync(HttpResponse, String, CancellationToken)</a></td> 
   <td> <p>将给定文本写入响应体。UTF-8编码将被使用</p> </td> 
  </tr> 
  <tr> 
   <td colspan="2"><a href="https://docs.microsoft.com/zh-cn/dotnet/api/microsoft.aspnetcore.http.responseextensions.clear?view=aspnetcore-2.1#Microsoft_AspNetCore_Http_ResponseExtensions_Clear_Microsoft_AspNetCore_Http_HttpResponse_" title="Clear(HttpResponse)" rel="nofollow">Clear(HttpResponse)</a></td> 
  </tr> 
  <tr> 
   <td><a href="https://docs.microsoft.com/zh-cn/dotnet/api/microsoft.aspnetcore.http.sendfileresponseextensions.sendfileasync?view=aspnetcore-2.1#Microsoft_AspNetCore_Http_SendFileResponseExtensions_SendFileAsync_Microsoft_AspNetCore_Http_HttpResponse_Microsoft_Extensions_FileProviders_IFileInfo_System_Int64_System_Nullable_System_Int64__System_Threading_CancellationToken_" title="SendFileAsync(HttpResponse, IFileInfo, Int64, Nullable<Int64>, CancellationToken)" rel="nofollow">SendFileAsync(HttpResponse, IFileInfo, Int64, Nullable&lt;Int64&gt;, CancellationToken)</a>&nbsp; &nbsp; &nbsp;</td> 
   <td> <p>使用Sendfile 扩展发送给定的文件</p> </td> 
  </tr> 
  <tr> 
   <td><a href="https://docs.microsoft.com/zh-cn/dotnet/api/microsoft.aspnetcore.http.sendfileresponseextensions.sendfileasync?view=aspnetcore-2.1#Microsoft_AspNetCore_Http_SendFileResponseExtensions_SendFileAsync_Microsoft_AspNetCore_Http_HttpResponse_Microsoft_Extensions_FileProviders_IFileInfo_System_Threading_CancellationToken_" title="SendFileAsync(HttpResponse, IFileInfo, CancellationToken)" rel="nofollow">SendFileAsync(HttpResponse, IFileInfo, CancellationToken)</a></td> 
   <td> <p>Sends the given file using the SendFile extension.</p> </td> 
  </tr> 
  <tr> 
   <td><a href="https://docs.microsoft.com/zh-cn/dotnet/api/microsoft.aspnetcore.http.sendfileresponseextensions.sendfileasync?view=aspnetcore-2.1#Microsoft_AspNetCore_Http_SendFileResponseExtensions_SendFileAsync_Microsoft_AspNetCore_Http_HttpResponse_System_String_System_Int64_System_Nullable_System_Int64__System_Threading_CancellationToken_" title="SendFileAsync(HttpResponse, String, Int64, Nullable<Int64>, CancellationToken)" rel="nofollow">SendFileAsync(HttpResponse, String, Int64, Nullable&lt;Int64&gt;, CancellationToken)</a></td> 
   <td> <p>Sends the given file using the SendFile extension.</p> </td> 
  </tr> 
  <tr> 
   <td><a href="https://docs.microsoft.com/zh-cn/dotnet/api/microsoft.aspnetcore.http.sendfileresponseextensions.sendfileasync?view=aspnetcore-2.1#Microsoft_AspNetCore_Http_SendFileResponseExtensions_SendFileAsync_Microsoft_AspNetCore_Http_HttpResponse_System_String_System_Threading_CancellationToken_" title="SendFileAsync(HttpResponse, String, CancellationToken)" rel="nofollow">SendFileAsync(HttpResponse, String, CancellationToken)</a></td> 
   <td> <p>Sends the given file using the SendFile extension.</p> </td> 
  </tr> 
 </tbody> 
</table>

![watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBAeGlhb2NoZW5YSUhVQQ_size_19_color_FFFFFF_t_70_g_se_x_16 1][]

# 四、 **HttpContext.Item** #

**HttpContext.Item** 是一个字典集合类型，具体类型为 **IDictionary<TModel,TModel>**。

打开 Index.Cshtml ，用下面代码复制替换

@model Microsoft.AspNetCore.Http.HttpContext
    @{
        Layout = null;
    }
    @{
        List<string> i = new List<string>();
        i.Add("a");
        i.Add("b");
        i.Add("c");
        i.Add("d");
        i.Add("e");
        i.Add("f");
        i.Add("g");
        i.Add("h");
        i.Add("i");
    
        Model.Items["Test"] = i;       
        /*
            Model.Items 是字典类型
            这里设置 键 Test
                     值 i ,它的值是 List<string> 类型
        */
    
    foreach(var item in Model.Items["Test"] as List<string>) //字典类型，必须先用 as 转为对应类型
    {
        <br> @item
        
    }
    }

运行效果如下：

![watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBAeGlhb2NoZW5YSUhVQQ_size_9_color_FFFFFF_t_70_g_se_x_16][]

[181f8e58ddd74daf1969e5f1bfa4da78.png]: /images/20220828/71de27ce22f9467f9e6b8c659f0a3f21.png
[4996a311030e479c0625f90b881e3a76.png]: /images/20220828/c3e797ed3be4473c9f7244c39ab4686a.png
[ASP.NETCore_Kestrel]: https://www.cnblogs.com/xiaoliangge/p/8387772.html
[watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBAeGlhb2NoZW5YSUhVQQ_size_20_color_FFFFFF_t_70_g_se_x_16]: /images/20220828/c59a92871c394c33a9350f2d8fecfde2.png
[watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBAeGlhb2NoZW5YSUhVQQ_size_20_color_FFFFFF_t_70_g_se_x_16 1]: /images/20220828/bf11f64ed730451f8b4779729a142730.png
[watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBAeGlhb2NoZW5YSUhVQQ_size_16_color_FFFFFF_t_70_g_se_x_16]: /images/20220828/31de7752f2a24b5087f6a4ae6deb8674.png
[watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBAeGlhb2NoZW5YSUhVQQ_size_19_color_FFFFFF_t_70_g_se_x_16]: /images/20220828/c8a8012f99074005b056cda5d73bb23c.png
[HttpRequest]: https://www.cnblogs.com/Sea1ee/p/7240943.html
[watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBAeGlhb2NoZW5YSUhVQQ_size_19_color_FFFFFF_t_70_g_se_x_16 1]: /images/20220828/d29146c120dd400497646ef08a3511d3.png
[watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBAeGlhb2NoZW5YSUhVQQ_size_9_color_FFFFFF_t_70_g_se_x_16]: /images/20220828/bcc8aabcfe6c48ed80284b6d324f163a.png