HttpClient替换HttpWebRequest–以GET和POST请求为例说明

首先说一下httprequest、webclient和httpclient的关系：httprequest是基层的请求方式，webclient是对httprequest的简化封装，在webclient中有对httprequest的默认设置；httpclient是重写的请求方式，相对于httprequest更简单实现异步请求，是.netcore中更推崇的方式。

说明：以下代码中 在getaccesstoken(async)中调用了调用了postmail(async)方式,其中在getaccesstoken(async)实现get请求，在postmail(async)中实现post请求

一、对比一下httprequest与httpclient实现get请求的过程区别（其实很相似，但httpclient轻松实现了异步）

1）httprequest的get请求

 public actionresult<string> getaccesstoken()
        {  //get获取accesstoken的参数 corid
            string uri = "你的url";
            //创建请求
  //httpwebrequest request = (httpwebrequest)webrequest.create(uri);
            //webclient是对httpwebrequest的抽象,webclient使用简单，但速度慢;restsharp兼具webclient和httpwebclient的优点；httpclient是.netcore中的概念，更适合异步编程
            webrequest request = webrequest.create(uri);
            //请求设置
            request.credentials = credentialcache.defaultcredentials;
            //创建应答接收
            webresponse response = request.getresponse();
            //创建应答读写流
            string accesstoken;
            using (stream streamresponse=response.getresponsestream())
            {
                streamreader reader = new streamreader(streamresponse);
                string responsefromserver = reader.readtoend();
                jobject res = (jobject)jsonconvert.deserializeobject(responsefromserver);
                 accesstoken = res["access_token"].tostring();
                reader.close();
            }
            //获得许可证凭证
            postmail(accesstoken);
            //关闭响应
            response.close();
            return "success";
        }

2）httpclient的get请求

public async task<actionresult<string>> getaccesstokenasync()
        {
            string uri = "你的url";
            httpclienthandler handler = new httpclienthandler
            {
                //设置是否发送凭证信息，有的服务器需要验证身份，不是所有服务器需要
                usedefaultcredentials = false
                
            };
            httpclient httpclient = new httpclient(handler);
            httpresponsemessage response = await httpclient.getasync(uri);
            response.ensuresuccessstatuscode();
            string accesstoken;
            //回复结果直接读成字符串
            string resp = await response.content.readasstringasync();
            jobject json = (jobject)jsonconvert.deserializeobject(resp);
            accesstoken = json["access_token"].tostring();
            //采用流读数据
            //using (stream streamresponse = await response.content.readasstreamasync())
            //{
            //    streamreader reader = new streamreader(streamresponse);
            //    string responsefromserver = reader.readtoend();
            //    jobject res = (jobject)jsonconvert.deserializeobject(responsefromserver);
            //    accesstoken = res["access_token"].tostring();
            //    reader.close();
            //}
            //获得许可证凭证
            postmailasync(accesstoken);
            //关闭响应
            return "success";
        }

二、对比一下httprequest与httpclient实现post请求的过程区别

1)httprequest的post请求

  public void postmail(string accesstoken)
        {    //post的api
            string uri = "https://qyapi.weixin.qq.com/cgi-bin/message/send?access_token=" + accesstoken;
            //创建请求
            webrequest mywebrequest = webrequest.create(uri);
            //请求设置
            mywebrequest.credentials = credentialcache.defaultcredentials;
            mywebrequest.contenttype = "application/json;charset=utf-8";
            mywebrequest.method = "post";
            //向服务器发送的内容
            using (stream streamresponse = mywebrequest.getrequeststream())
            {
                //创建json格式的发送内容
                jobject postedjobject = new jobject
                {
                    //在此处设置发送内容及对象
                    { "touser", "heavy" },
                    { "msgtype", "text" },
                    { "agentid", 1000002 }
                };
                jobject text = new jobject
            {
                {"content","内容来自网站--内容可自行编辑--heavy"}
            };
                postedjobject.add("text", text);
                postedjobject.add("safe", 0);
                //将传送内容编码
                string paramstring = postedjobject.tostring(newtonsoft.json.formatting.none, null);
                byte[] bytearray = encoding.utf8.getbytes(paramstring);
                //向请求中写入内容
                streamresponse.write(bytearray, 0, bytearray.length);
            }
            //创建应答
            webresponse mywebresponse = mywebrequest.getresponse();
            //创建应答的读写流
            string responsefromserver;
            using (stream streamresponse = mywebresponse.getresponsestream())
            {
                streamreader streamread = new streamreader(streamresponse);
                responsefromserver = streamread.readtoend();
            }
            //关闭应答
            mywebresponse.close();
        }

2）httpclient的post请求

 public async void postmailasync(string accesstoken)
        {
            string uri = "https://qyapi.weixin.qq.com/cgi-bin/message/send?access_token=" + accesstoken;
            httpclienthandler handler = new httpclienthandler
            {
                usedefaultcredentials = true,
               
            };
            httpclient httpclient = new httpclient(handler);
            jobject postedjobject = new jobject
                {
                    //在此处设置发送内容及对象
                    { "touser", "heavy" },
                    { "msgtype", "text" },
                    { "agentid", 1000002 }
                };
            jobject text = new jobject
            {
                {"content","内容来自网站--内容可自行编辑--heavy"}
            };
            postedjobject.add("text", text);
            postedjobject.add("safe", 0);
            //将传送内容编码
            string paramstring = postedjobject.tostring(newtonsoft.json.formatting.none, null);
            //byte[] bytearray = encoding.utf8.getbytes(paramstring);
            httpcontent httpcontent = new stringcontent(paramstring,encoding.utf8,"application/json");
            httpresponsemessage response = await httpclient.postasync(uri, httpcontent);
           //用来判断是否接收成功，否则抛出异常
            response.ensuresuccessstatuscode();
        }