在.net core 下如何進行http請求？

本篇文章主要介紹了詳解c# .net core 下的網路請求，大致介紹下在.net core 下如何進行http請求，主要仍然是GET和POST方法，有興趣的可以瞭解下

本文章是在VS2017的環境下，.net core 1.1版本以上。

在這期間，由於.net core 並不基於IIS，我們的過去的網路請求代碼在.net core架構下，有可能會出現不相容，報錯的現象。這裡大致介紹下在.net core 下如何進行http請求，主要仍然是GET和POST方法，有錯誤的地方，歡迎指正！

先來說POST,POST我實現了三種方法，前兩種基於的原理是完全一致的，後面的有些小小的差異，但他們的本質都是http請求，本質上是無區別的，只是實現方法有所不同。

廢話不多說，上代碼：

POST非同步方法呼叫：

 /// <summary>    /// 非同步請求post（索引值對形式,可等待的）    /// </summary>    /// <param name="uri">網路基址("http://localhost:59315")</param>    /// <param name="url">網路的地址("/api/UMeng")</param>    /// <param name="formData">索引值對List<KeyValuePair<string, string>> formData = new List<KeyValuePair<string, string>>();formData.Add(new KeyValuePair<string, string>("userid", "29122"));formData.Add(new KeyValuePair<string, string>("umengids", "29122"));</param>    /// <param name="charset">編碼格式</param>    /// <param name="mediaType">頭媒體類型</param>    /// <returns></returns>    public async Task<string> HttpPostAsync(string uri, string url, List<KeyValuePair<string, string>> formData = null, string charset = "UTF-8", string mediaType = "application/x-www-form-urlencoded")    {            string tokenUri = url;      var client = new HttpClient();      client.BaseAddress = new Uri(uri);      HttpContent content = new FormUrlEncodedContent(formData);      content.Headers.ContentType = new MediaTypeHeaderValue(mediaType);      content.Headers.ContentType.CharSet = charset;      for (int i = 0; i < formData.Count; i++)      {        content.Headers.Add(formData[i].Key, formData[i].Value);      }            HttpResponseMessage resp = await client.PostAsync(tokenUri, content);      resp.EnsureSuccessStatusCode();      string token = await resp.Content.ReadAsStringAsync();      return token;    }

POST同步方法：

/// <summary>    /// 同步請求post（索引值對形式）    /// </summary>    /// <param name="uri">網路基址("http://localhost:59315")</param>    /// <param name="url">網路的地址("/api/UMeng")</param>    /// <param name="formData">索引值對List<KeyValuePair<string, string>> formData = new List<KeyValuePair<string, string>>();formData.Add(new KeyValuePair<string, string>("userid", "29122"));formData.Add(new KeyValuePair<string, string>("umengids", "29122"));</param>    /// <param name="charset">編碼格式</param>    /// <param name="mediaType">頭媒體類型</param>    /// <returns></returns>    public string HttpPost(string uri, string url, List<KeyValuePair<string, string>> formData = null, string charset = "UTF-8", string mediaType = "application/x-www-form-urlencoded")    {            string tokenUri = url;      var client = new HttpClient();      client.BaseAddress = new Uri(uri);      HttpContent content = new FormUrlEncodedContent(formData);      content.Headers.ContentType = new MediaTypeHeaderValue(mediaType);      content.Headers.ContentType.CharSet = charset;      for (int i = 0; i < formData.Count; i++)      {        content.Headers.Add(formData[i].Key, formData[i].Value);      }      var res = client.PostAsync(tokenUri, content);      res.Wait();      HttpResponseMessage resp = res.Result;            var res2 = resp.Content.ReadAsStringAsync();      res2.Wait();      string token = res2.Result;      return token;    }

遺憾的是，同步方法也是基於非同步實現的，個人認為這樣做會加大系統開銷。如果各位有其他的高效實現，請不吝賜教！

接下來是通過流的方式進行POST：

public string Post(string url, string data, Encoding encoding, int type)    {      try      {        HttpWebRequest req = WebRequest.CreateHttp(new Uri(url));        if (type == 1)        {          req.ContentType = "application/json;charset=utf-8";        }        else if (type == 2)        {          req.ContentType = "application/xml;charset=utf-8";        }        else        {          req.ContentType = "application/x-www-form-urlencoded;charset=utf-8";        }        req.Method = "POST";        //req.Accept = "text/xml,text/javascript";        req.ContinueTimeout = 60000;        byte[] postData = encoding.GetBytes(data);        Stream reqStream = req.GetRequestStreamAsync().Result;        reqStream.Write(postData, 0, postData.Length);        reqStream.Dispose();        var rsp = (HttpWebResponse)req.GetResponseAsync().Result;        var result = GetResponseAsString(rsp, encoding);        return result;              }      catch (Exception ex)      {        throw;      }    }

private string GetResponseAsString(HttpWebResponse rsp, Encoding encoding)    {      Stream stream = null;      StreamReader reader = null;      try      {        // 以字元流的方式讀取HTTP響應        stream = rsp.GetResponseStream();        reader = new StreamReader(stream, encoding);        return reader.ReadToEnd();      }      finally      {        // 釋放資源        if (reader != null) reader.Dispose();        if (stream != null) stream.Dispose();        if (rsp != null) rsp.Dispose();      }    }

這種方式的POST還是將資料寫入到流裡面，進行POST,之所以寫前兩個key-value的形式，是為了符合java或者oc的風格，在c#書寫的webapi中，由於接收形式是{=value}而不是{key=value}(由webapi的性質決定)，後續我會說如何在webapi中接收（key-value）的形式，適當避免.net後台人員與android和ios的矛盾，從而達到社會主義民主社會的長治久安。

接下來是get，同樣同步非同步都是由非同步實現的，還請各位看官輕噴。

GET：

 /// <summary>    /// 非同步請求get(UTF-8)    /// </summary>    /// <param name="url">連結地址</param>        /// <param name="formData">寫在header中的內容</param>    /// <returns></returns>    public static async Task<string> HttpGetAsync(string url, List<KeyValuePair<string, string>> formData = null)    {      HttpClient httpClient = new HttpClient();      HttpContent content = new FormUrlEncodedContent(formData);      if (formData != null)      {        content.Headers.ContentType = new MediaTypeHeaderValue("application/x-www-form-urlencoded");        content.Headers.ContentType.CharSet = "UTF-8";        for (int i = 0; i < formData.Count; i++)        {          content.Headers.Add(formData[i].Key, formData[i].Value);        }      }      var request = new HttpRequestMessage()      {        RequestUri = new Uri(url),        Method = HttpMethod.Get,      };      for (int i = 0; i < formData.Count; i++)      {        request.Headers.Add(formData[i].Key, formData[i].Value);      }      var resp = await httpClient.SendAsync(request);      resp.EnsureSuccessStatusCode();      string token = await resp.Content.ReadAsStringAsync();      return token;    }

 /// <summary>    /// 同步get請求    /// </summary>    /// <param name="url">連結地址</param>        /// <param name="formData">寫在header中的索引值對</param>    /// <returns></returns>    public string HttpGet(string url, List<KeyValuePair<string, string>> formData = null)    {      HttpClient httpClient = new HttpClient();      HttpContent content = new FormUrlEncodedContent(formData);      if (formData != null)      {        content.Headers.ContentType = new MediaTypeHeaderValue("application/x-www-form-urlencoded");        content.Headers.ContentType.CharSet = "UTF-8";        for (int i = 0; i < formData.Count; i++)        {          content.Headers.Add(formData[i].Key, formData[i].Value);        }      }      var request = new HttpRequestMessage()      {        RequestUri = new Uri(url),        Method = HttpMethod.Get,      };      for (int i = 0; i < formData.Count; i++)      {        request.Headers.Add(formData[i].Key, formData[i].Value);      }      var res = httpClient.SendAsync(request);      res.Wait();      var resp = res.Result;      Task<string> temp = resp.Content.ReadAsStringAsync();      temp.Wait();      return temp.Result;    }

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