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：

 /// <summary>
    /// 异步请求post（键值对形式,可等待的）
    /// </summary>
    /// <param name="uri">网络基址("http://localhost:59315")</param>
    /// <param name="url">网络的地址("/api/umeng")</param>
    /// <param name="formdata">键值对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">编码格式</param>
    /// <param name="mediatype">头媒体类型</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>
    /// 同步请求post（键值对形式）
    /// </summary>
    /// <param name="uri">网络基址("http://localhost:59315")</param>
    /// <param name="url">网络的地址("/api/umeng")</param>
    /// <param name="formdata">键值对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">编码格式</param>
    /// <param name="mediatype">头媒体类型</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;
    }

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：

 /// <summary>
    /// 异步请求get(utf-8)
    /// </summary>
    /// <param name="url">链接地址</param>    
    /// <param name="formdata">写在header中的内容</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请求
    /// </summary>
    /// <param name="url">链接地址</param>    
    /// <param name="formdata">写在header中的键值对</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;
    }

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。