HttpClientStudy/Docs/1.3.6.基础使用.使用代理.ipynb

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   "source": [
    "# HttpClient 使用代理功能"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "实际开发中，HttpClient 通过代理访问目标服务器是常见的需求。\n",
    "\n",
    "本文将全面介绍如何在 .NET 中配置 HttpClient 使用代理（Proxy）功能，包括基础使用方式、代码示例、以及与依赖注入结合的最佳实践。\n",
    "\n",
    "> 注意：运行代码之前，先开启`Fiddler Classic`及其代理功能，充当代理服务器。"
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   "source": [
    "## 初始化"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### 开启`Fiddler Classic`及其代理功能，充当代理服务器"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "![代理服务器](./Assets/HttpClient-代理服务器设置.jpg)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### 导入初始终化笔记文件，并且执行一次"
   ]
  },
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     "data": {
      "text/markdown": [
       "## 初始化\n",
       "这是全局共用文件，包括Nuget包引用、全局类库引用、全局文件引用、全局命名空间引用、全局变量、全局方法、全局类定义等功能。\n",
       "\n",
       "在业务笔记中引用，执行其它单元格之前先执行一次。"
      ]
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       "<div><div></div><div></div><div><strong>Installed Packages</strong><ul><li><span>Microsoft.Extensions.DependencyInjection, 9.0.5</span></li><li><span>Microsoft.Extensions.Http, 9.0.5</span></li><li><span>Microsoft.Extensions.Http.Polly, 9.0.5</span></li><li><span>Microsoft.Extensions.Logging, 9.0.5</span></li><li><span>Microsoft.Extensions.Logging.Console, 9.0.5</span></li><li><span>Microsoft.Net.Http.Headers, 9.0.5</span></li><li><span>Polly, 8.5.2</span></li><li><span>Refit, 8.0.0</span></li><li><span>Refit.HttpClientFactory, 8.0.0</span></li><li><span>System.Net.Http.Json, 9.0.5</span></li></ul></div></div>"
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     "text": [
      "配置文件根目录：c:\\Users\\ruyu\\Desktop\\HttpClientStudy\\Docs\\Publish\\HttpClientStudy.Core\n",
      "配置文件根目录：c:\\Users\\ruyu\\Desktop\\HttpClientStudy\\Docs\\Publish\\HttpClientStudy.Core\n",
      "启动WebApi项目...\n",
      "程序[c:\\Users\\ruyu\\Desktop\\HttpClientStudy\\Docs\\Publish\\HttpClientStudy.WebApp\\HttpClientStudy.WebApp.exe]已在新的命令行窗口执行。如果未出现新命令行窗口，可能是程序错误造成窗口闪现！\n",
      "已启动WebApi项目,保持窗口打开状态！\n",
      "初始化完成！\n"
     ]
    }
   ],
   "source": [
    "#!import \"./Ini.ipynb\"\n",
    "\n",
    "//共享变量\n",
    "var fiddlerProxyAddress = \"127.0.0.1:8888\";\n"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## 🧩 什么是代理？"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "代理（Proxy）是一种中间服务器，用于转发客户端请求到目标服务器。它常用于以下目的：\n",
    "\n",
    "- 访问受限资源：企业内网中，通过代理服务器访问外部资源；\n",
    "- 提高安全性和隐私保护：代理可隐藏真实 IP 地址，保护目标服务器的隐私和数据安全；\n",
    "- 提高性能：代理可使用请求缓存和负载均衡等，减少目标服务器的压力，提高性能；\n",
    "- 方便调试、测试\n",
    "    - 代理服务器可记录请求和响应信息，方便调试和测试；\n",
    "    - `Fiddler Classic`等软件，默认是抓不到 HttpClient 的请求的，需要将其设置为代理服务器，才能抓取到 HttpClient 的请求;\n",
    "\n",
    "在 .NET HttpClient 中，可以通过多种方式来设置代理服务器。"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## 🛠️ 设置 HttpClient 代理"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### ✅ 基本方式使用（无用户名密码）"
   ]
  },
  {
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   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "响应状态：OK\r\n"
     ]
    }
   ],
   "source": [
    "{   \n",
    "    // 设置 SocketsHttpHandler 使用代理\n",
    "    var handler = new SocketsHttpHandler()\n",
    "    {\n",
    "        UseProxy = true,\n",
    "        Proxy = new WebProxy(fiddlerProxyAddress),\n",
    "    };\n",
    "\n",
    "    // 创建 HttpClient，并且请求\n",
    "    using (var client = new HttpClient(handler))\n",
    "    {\n",
    "        var response = await client.GetAsync(\"https://www.baidu.com\");\n",
    "        \n",
    "        Console.WriteLine($\"响应状态：{response.StatusCode}\");\n",
    "    }\n",
    "}"
   ]
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   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "执行上面的单元格，应该在fiddler classic 中，抓到请求包：可以查看和管理详细信息.\n",
    "![Fillder 抓包](./Assets/HttpClient-代理-抓包.jpg)\n"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### ✅ 带用户名和密码的代理"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
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     "text": [
      "响应状态：OK\r\n"
     ]
    }
   ],
   "source": [
    "{   \n",
    "    // 设置 SocketsHttpHandler 使用代理\n",
    "    var handler = new SocketsHttpHandler()\n",
    "    {\n",
    "        UseProxy = true,\n",
    "        Proxy = new WebProxy(fiddlerProxyAddress)\n",
    "        {\n",
    "            //正式项目：机密数据一定要脱敏处理或者使用环境变量、机密管理器等手段\n",
    "            //因为Fiddler代理服务器，没有用户凭据要求，所以此处随意填写的。需要的话，真实填写正确的用户凭据。\n",
    "            Credentials = new NetworkCredential(\"username\", \"password\"),\n",
    "        },\n",
    "    };\n",
    "\n",
    "    // 创建 HttpClient，并且请求\n",
    "    using (var client = new HttpClient(handler))\n",
    "    {\n",
    "        var response = await client.GetAsync(\"https://www.baidu.com\");\n",
    "        Console.WriteLine($\"响应状态：{response.StatusCode}\");\n",
    "    }\n",
    "}"
   ]
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   },
   "source": [
    "### 📦 在IoC和工厂中使用 Proxy [推荐方式]"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "在 ASP.NET Core 或基于 IServiceCollection 的项目中，可以通过 UseSocketsHttpHandler 扩展方法，统一管理代理服务器配置。\n",
    "\n",
    "还可以根据客户端的命名不同，进行不同的代理服务器配置！"
   ]
  },
  {
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   "outputs": [
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     "name": "stdout",
     "output_type": "stream",
     "text": [
      "正常请求,响应内容为： Pong\r\n"
     ]
    }
   ],
   "source": [
    "//IoC或工厂中设置代理\n",
    "{\n",
    "   //IoC\n",
    "   var services = new ServiceCollection();\n",
    "\n",
    "   //默认命名客户端\n",
    "   services\n",
    "      .AddHttpClient<HttpClient>(string.Empty)\n",
    "      .ConfigureHttpClient(client => \n",
    "      {\n",
    "         client.BaseAddress = new Uri(webApiBaseUrl);\n",
    "         client.Timeout = TimeSpan.FromSeconds(10);\n",
    "      })\n",
    "\n",
    "      //配置代理服务器\n",
    "      .UseSocketsHttpHandler(handlerBuilder =>\n",
    "      {\n",
    "         handlerBuilder.Configure((handler,s) => \n",
    "         {\n",
    "            handler.Proxy = new WebProxy(fiddlerProxyAddress);\n",
    "         }); \n",
    "      });\n",
    "\n",
    "   //发送请求\n",
    "   var factory = services.BuildServiceProvider().GetRequiredService<IHttpClientFactory>();\n",
    "\n",
    "   //正常请求\n",
    "   var defaultClient = factory.CreateClient();\n",
    "   var defaultContent = await defaultClient.GetStringAsync(\"api/hello/ping\");\n",
    "   Console.WriteLine($\"正常请求,响应内容为： {defaultContent}\");\n",
    "}"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### 🔄 动态切换代理服务器\n"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "要根据请求的不同(请求地址、请求方法、请求头、请求参数等)，动态选择使用一同的代理服务器，可以使用Pipeline中间件，来管理。"
   ]
  },
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   "outputs": [
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     "output_type": "stream",
     "text": [
      "LoggerDelegatingHandler -> SendAsync -> Before\n",
      "ProxySelectorLastHandler -> SendAsync -> Before\n",
      "ProxySelectorLastHandler -> SendAsync -> After\n",
      "LoggerDelegatingHandler -> SendAsync -> After\n",
      "OK\n",
      "---------------------------------------------------\n",
      "ProxySelectorLastHandler -> SendAsync -> Before\n",
      "ProxySelectorLastHandler -> SendAsync -> After\n",
      "OK\n"
     ]
    }
   ],
   "source": [
    "///<summary>\n",
    "/// 代理服务选择器中间件\n",
    "/// 注意：此中间件会短路，必须设置为最后一个中间件\n",
    "///</summary>\n",
    "public class ProxySelectorLastHandler : DelegatingHandler\n",
    "{\n",
    "    /// <summary>\n",
    "    /// 拦截请求，并动态设置代理\n",
    "    /// 注意：会短路其它中间件，要放最后\n",
    "    /// </summary>\n",
    "    protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken ct)\n",
    "    {\n",
    "        Console.WriteLine(\"ProxySelectorLastHandler -> SendAsync -> Before\");\n",
    "        //动态选择示例\n",
    "        var proxy = request.RequestUri.Host switch\n",
    "        {\n",
    "            string url when url.Contains(\"baidu\") => new WebProxy(\"127.0.0.1:8888\"),\n",
    "            string url when url.Contains(\"qq\") => new WebProxy(\"127.0.0.1:8888\"),\n",
    "            _ => null\n",
    "        };\n",
    "\n",
    "        InnerHandler = new SocketsHttpHandler\n",
    "        {\n",
    "            Proxy = proxy,\n",
    "            UseProxy = proxy != null\n",
    "        };\n",
    "\n",
    "\n",
    "        //请求\n",
    "        HttpResponseMessage response = await base.SendAsync(request, ct);\n",
    "\n",
    "        Console.WriteLine(\"ProxySelectorLastHandler -> SendAsync -> After\");\n",
    "\n",
    "        return response;\n",
    "    }\n",
    "}\n",
    "\n",
    "//日志中间件(管道类)\n",
    "public class LoggerDelegatingHandler : DelegatingHandler\n",
    "{\n",
    "    protected override HttpResponseMessage Send(HttpRequestMessage request, CancellationToken cancellationToken)\n",
    "    {\n",
    "        Console.WriteLine(\"LoggerDelegatingHandler -> Send -> Before\");\n",
    "\n",
    "        HttpResponseMessage response = base.Send(request, cancellationToken);\n",
    "\n",
    "        Console.WriteLine(\"LoggerDelegatingHandler -> Send -> After\");\n",
    "\n",
    "        return response;\n",
    "    }\n",
    "\n",
    "    protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)\n",
    "    {\n",
    "        Console.WriteLine(\"LoggerDelegatingHandler -> SendAsync -> Before\");\n",
    "\n",
    "        HttpResponseMessage response = await base.SendAsync(request, cancellationToken);\n",
    "\n",
    "        Console.WriteLine(\"LoggerDelegatingHandler -> SendAsync -> After\");\n",
    "\n",
    "        return response;\n",
    "    }\n",
    "}\n",
    "\n",
    "//使用：ProxySelectorLastHandler必须设置为最后一个中间件\n",
    "{\n",
    "    var handlerLink = new LoggerDelegatingHandler()\n",
    "    {\n",
    "        InnerHandler = new ProxySelectorLastHandler(),\n",
    "    };\n",
    "\n",
    "    var myClient = new HttpClient(handlerLink);\n",
    "    var response = await myClient.GetAsync(\"https://www.qq.com\");\n",
    "\n",
    "    Console.WriteLine(response.StatusCode);\n",
    "    Console.WriteLine(\"---------------------------------------------------\");\n",
    "}\n",
    "\n",
    "\n",
    "// ProxySelectorLastHandler 不是最后一个的话，其它中间件无效(被短路)\n",
    "{\n",
    "    var handlerLink = new ProxySelectorLastHandler()\n",
    "    {\n",
    "        InnerHandler = new LoggerDelegatingHandler (),\n",
    "    };\n",
    "\n",
    "    var myClient = new HttpClient(handlerLink);\n",
    "    var response = await myClient.GetAsync(\"https://www.qq.com\");\n",
    "\n",
    "    Console.WriteLine(response.StatusCode);\n",
    "}\n",
    "\n",
    "//注意看输出：后面的没有日志中间件的任何输出"
   ]
  },
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   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## 🔐 HTTPS 代理信任问题"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "当使用 HTTPS 代理时，可能会遇到 SSL/TLS 证书不被信任的问题，尤其是在测试环境中使用自签名证书。"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### ✅解决方法一：忽略证书验证（⚠️ 注意：仅用于开发环境）"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
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   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "OK\r\n"
     ]
    }
   ],
   "source": [
    "var handler = new HttpClientHandler\n",
    "{\n",
    "    Proxy = new WebProxy(fiddlerProxyAddress),\n",
    "    UseProxy = true,\n",
    "    ServerCertificateCustomValidationCallback = (message, cert, chain, errors) => true\n",
    "};\n",
    "\n",
    "using (var client = new HttpClient(handler))\n",
    "{ \n",
    "    var response = await client.GetAsync(\"https://www.baidu.com\");\n",
    "    Console.WriteLine(response.StatusCode);\n",
    "};\n"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### ✅ 解决方法二：手动添加根证书信任"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {
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     "kernelName": "csharp"
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    "vscode": {
     "languageId": "polyglot-notebook"
    }
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "OK\r\n"
     ]
    }
   ],
   "source": [
    "using System.Security;\n",
    "using System.Security.Cryptography;\n",
    "using System.Security.Cryptography.X509Certificates;\n",
    "\n",
    "var file = Environment.CurrentDirectory + \"\\\\Assets\\\\FiddlerRoot.cer\";\n",
    "//Console.WriteLine(file);\n",
    "var rootCert = System.Security.Cryptography.X509Certificates.X509CertificateLoader.LoadCertificateFromFile(file);\n",
    "\n",
    "var handler = new HttpClientHandler\n",
    "{\n",
    "    Proxy = new WebProxy(fiddlerProxyAddress),\n",
    "    UseProxy = true,\n",
    "    ServerCertificateCustomValidationCallback = (request, cert, chain, errors) =>\n",
    "    {\n",
    "        //return true;\n",
    "        return chain.ChainElements.Any(x => x.Certificate.Thumbprint == cert.Thumbprint); // 验证证书链包含指定根证书\n",
    "    }\n",
    "};\n",
    "\n",
    "using (var client = new HttpClient(handler))\n",
    "{ \n",
    "    var response = await client.GetAsync(\"https://www.baidu.com\");\n",
    "    Console.WriteLine(response.StatusCode);\n",
    "};"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## 📌 总结"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "通过本文，你应该掌握了以下内容：\n",
    "\n",
    "+ 如何在 HttpClient 中直接设置代理\n",
    "+ 如何在依赖注入系统中配置全局代理\n",
    "+ 如何通过环境变量设置代理\n",
    "+ 如何验证代理是否生效\n",
    "+ 实际使用中的注意事项\n",
    "+ 动态选择及证书信任"
   ]
  }
 ],
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