.NETCore HttpWebRequest-旧方法不起作用

Question

Before I upgraded to the newest .NetCore I was able to run the HttpWebRequest, add the headers and content Type and pull the stream of the JSON file from Twitch. Since the upgrade this is not working. I receive a Web Exception each time I go to get the response Stream. Nothing has changed with twitch because it still works with the old Bot. The old code is below:

private const string Url = "https://api.twitch.tv/kraken/streams/channelname";
HttpWebRequest request;
        try
        {
            request = (HttpWebRequest)WebRequest.Create(Url);
        }

        request.Method = "Get";
        request.Timeout = 12000;
        request.ContentType = "application/vnd.twitchtv.v5+json";
        request.Headers.Add("Client-ID", "ID");
        try
        {
            using (var s = request.GetResponse().GetResponseStream())
            {
                if (s != null)
                    using (var sr = new StreamReader(s))
                    {

                    }
            }
        }

I have done some research and found that I may need to start using either an HttpClient or HttpRequestMessage. I have tried going about this but when adding headers content type the program halts and exits. after the first line here: (when using HttpsRequestMessage)

request.Content.Headers.ContentType.MediaType = "application/vnd.twitchtv.v5+json";
request.Content.Headers.Add("Client-ID", "rbp1au0xk85ej6wac9b8s1a1amlsi5");

Answer 1

You are trying to add a ContentType header, but what you really want is to add an Accept header (your request is a GET and ContentType is used only on requests which contain a body, eg POST or PUT ).

In .NET Core you need to use HttpClient , but remember that to correctly use it you need to leverage the use of async and await .

Here it is an example:

using System.Net.Http;
using System.Net.Http.Headers;

private const string Url = "https://api.twitch.tv/kraken/streams/channelname";

public static async Task<string> GetResponseFromTwitch()
{
    using(var client = new HttpClient())
    {
        client.DefaultRequestHeaders.Accept.Clear();
        client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/vnd.twitchtv.v5+json"));
        client.DefaultRequestHeaders.Add("Client-ID", "MyId");

        using(var response = await client.GetAsync(Url))
        {
            response.EnsureSuccessStatusCode();

            return await response.Content.ReadAsStringAsync(); // here we return the json response, you may parse it
        }
    }    
}