详解c# .net core 下的网络请求

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> formData = new List>();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> 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> formData = new List>();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> 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> 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> 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;
    }

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持考高分网。