在.net core 下如何进行http请求？

后端开发|C#.Net教程 本篇文章主要介绍了详解c# .net core 下的网络请求，大致介绍下在.net core 下如何进行http请求，主要仍然是GET和POST方法，有兴趣的可以了解下本文章是在VS2017的环境下，.net core 1.1版本以上。在这期间，由于.net core 并不基于IIS，我们的过去的网络请求代码在.net core框架下，有可能会出现不兼容，报错的现象。这里大致介绍下在.net core 下如何进行http请求，主要仍然是GET和POST方法，有错误的地方，欢迎指正！先来说POST,POST我实现了三种方法，前两种基于的原理是完全一致的，后面的有些小小的差异，但他们的本质都是http请求，本质上是无区别的，只是实现方法有所不同。

废话不多说，上代码：

POST异步方法：

 /// 
    /// 异步请求post（键值对形式,可等待的）    /// 
    /// 网络基址("http://localhost:59315")    /// 网络的地址("/api/UMeng")    /// 键值对List<KeyValuePair> formData = new List<KeyValuePair>();formData.Add(new KeyValuePair("userid", "29122"));formData.Add(new KeyValuePair("umengids", "29122"));    /// 编码格式    /// 头媒体类型    ///     public async Task HttpPostAsync(string uri, string url, List<KeyValuePair> 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：

/// 
    /// 同步请求post（键值对形式）    /// 
    /// 网络基址("http://localhost:59315")    /// 网络的地址("/api/UMeng")    /// 键值对List<KeyValuePair> formData = new List<KeyValuePair>();formData.Add(new KeyValuePair("userid", "29122"));formData.Add(new KeyValuePair("umengids", "29122"));    /// 编码格式    /// 头媒体类型    ///     public string HttpPost(string uri, string url, List<KeyValuePair> 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;    }

遗憾的是，同步方法也是基于异步实现的，个人认为这样做会加大系统开销。如果各位有其他的高效实现，请不吝赐教！

接下来是通过流的方式进行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      {        // 以字符流的方式读取HTTP响应        stream = rsp.GetResponseStream();        reader = new StreamReader(stream, encoding);        return reader.ReadToEnd();      }      finally      {        // 释放资源        if (reader != null) reader.Dispose();        if (stream != null) stream.Dispose();        if (rsp != null) rsp.Dispose();      }    }

这种方式的POST还是将数据写入到流里面，进行POST,之所以写前两个key-value的形式，是为了符合java或者oc的风格，在c#书写的webapi中，由于接收形式是{=value}而不是{key=value}(由webapi的性质决定)，后续我会说如何在webapi中接收（key-value）的形式，适当避免.net后台人员与android和ios的矛盾，从而达到社会主义民主社会的长治久安。

接下来是get，同样同步异步都是由异步实现的，还请各位看官轻喷。

GET：

 /// 
    /// 异步请求get(UTF-8)    /// 
    /// 链接地址        /// 写在header中的内容    ///     public static async Task HttpGetAsync(string url, List<KeyValuePair> 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;    }

 /// 
    /// 同步get请求    /// 
    /// 链接地址        /// 写在header中的键值对    ///     public string HttpGet(string url, List<KeyValuePair> 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 temp = resp.Content.ReadAsStringAsync();      temp.Wait();      return temp.Result;    }

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