c# - 如何在asp.net c#中根据URL获取https文件

Question

在我的要求中，我需要从 URL 获取文件。我试过了，但它总是抛出一个禁止的错误。请尝试解决这个问题。请查看我的代码。

var webRequest = WebRequest.Create("https://www.fda.gov/ucm/groups/fdagov-public/@fdagov-drugs-gen/documents/document/ucm509432.pdf");  
using (var response = webRequest.GetResponse())
   using (var content = response.GetResponseStream())
      using (var reader = new StreamReader(content))
      {
         var strContent = reader.ReadToEnd();
      }

Answer 1

当我查看来自服务器的响应内容时，我意识到它声明客户端需要支持 TLSv1.2。

要启用 TLSv1.2 支持，请在创建 HttpWebRequest 类之前添加以下行:(感谢 BugFinder 提供的直接枚举值提示)

ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;

我发布了完整的源代码。

您还可以看到，我测试了向服务器发送一些 header 以查看缺少其中一个 header 是否是问题所在:

class Program
{
    static void Main(string[] args)
    {
        ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;

        HttpWebRequest webRequest = HttpWebRequest.Create("https://www.fda.gov/ucm/groups/fdagov-public/@fdagov-drugs-gen/documents/document/ucm509432.pdf") as HttpWebRequest;
        webRequest.UserAgent = "Mozilla/5.0 (Windows NT 6.3; WOW64; Trident/7.0; Touch; rv:11.0) like Gecko";
        webRequest.Accept = "text/html, application/xhtml+xml, */*";
        webRequest.Headers.Add("Accept-Encoding", "gzip, deflate");
        webRequest.Headers.Add("Accept-Language", "tr-TR");
        webRequest.Headers.Add("DNT", "1");

        using (var
             response = webRequest.GetResponse())
        using (var content = response.GetResponseStream())
        using (var reader = new StreamReader(content))
        {
            var strContent = reader.ReadToEnd();
        }
    }
}