详解C# HttpWebRequest发送带有JSON Body的POST请求

很多博客都有描述到这个问题，那么为什么我还要写一篇文章来说一下呢，因为其他的都似乎已经过时了，会导致其实body 并没有发送过去。至于为什么不使用其他的诸如 HttpClient 之类的，是由于业务需要。

原来的处理方式

通过 GetRequestStream 来获取请求流，后把需要发送的 Json 数据写入到流中

private T PostDataViaHttpWebRequest<T>(string baseUrl,
          IReadOnlyDictionary<string, string> headers,
          IReadOnlyDictionary<string, string> urlParas,
          string requestBody=null)
      {
          var resuleJson = string.Empty;
          try
          {
              var apiUrl = baseUrl;

              if (urlParas != null)
                  urlParas.ForEach(p =>
                  {
                      if (apiUrl.IndexOf("{" + p.Key + "}") > -1)
                      {
                          apiUrl = apiUrl.Replace("{" + p.Key + "}", p.Value);
                      }
                      else
                      {
                          apiUrl += string.Format("{0}{1}={2}", apiUrl.Contains("?") ? "&" : "?", p.Key, p.Value);
                      }
                  }
              );
              
              var req = (HttpWebRequest)WebRequest.Create(apiUrl);
              req.Method = "POST";
              req.ContentType = "application/json"; 
              req.ContentLength = 0;

              if (!requestBody.IsNullOrEmpty())
              {
                  using (var postStream = req.GetRequestStream())
                  {
                      var postData = Encoding.ASCII.GetBytes(requestBody);
                      req.ContentLength = postData.Length;
                      postStream.Write(postData, 0, postData.Length);
                  }
              }

              if (headers != null)
              {
                  if (headers.Keys.Any(p => p.ToLower() == "content-type"))
                      req.ContentType = headers.SingleOrDefault(p => p.Key.ToLower() == "content-type").Value;
                  if (headers.Keys.Any(p => p.ToLower() == "accept"))
                      req.Accept = headers.SingleOrDefault(p => p.Key.ToLower() == "accept").Value;
              }

              var response = (HttpWebResponse)req.GetResponse();

              using(Stream stream = response.GetResponseStream())
              {
                  using (StreamReader reader = new StreamReader(stream, Encoding.GetEncoding("UTF-8")))
                  {
                      resuleJson = reader.ReadToEnd();
                  }
              }
          }
          catch (Exception ex)
          {
              return default(T);
          }
          return JsonConvert.DeserializeObject<T>(resuleJson);
      }

但是会发现，数据一直没有正常发送过去，而且代码还显得比较复杂

新的方式

这里修改一下写入 RequestStream 的方式，使用 StreamWriter 包装一下，然后直接写入需要发送的 Json 数据

private T PostDataViaHttpWebRequest<T>(string baseUrl,
          IReadOnlyDictionary<string, string> headers,
          IReadOnlyDictionary<string, string> urlParas,
          string requestBody=null)
      {
          var resuleJson = string.Empty;
          try
          {
              var apiUrl = baseUrl;

              if (urlParas != null)
                  urlParas.ForEach(p =>
                  {
                      if (apiUrl.IndexOf("{" + p.Key + "}") > -1)
                      {
                          apiUrl = apiUrl.Replace("{" + p.Key + "}", p.Value);
                      }
                      else
                      {
                          apiUrl += string.Format("{0}{1}={2}", apiUrl.Contains("?") ? "&" : "?", p.Key, p.Value);
                      }
                  }
              );
              
              var req = (HttpWebRequest)WebRequest.Create(apiUrl);
              req.Method = "POST";
              req.ContentType = "application/json"; //Defalt

              if (!requestBody.IsNullOrEmpty())
              {
                  using (var postStream = new StreamWriter(req.GetRequestStream()))
                  {
                      postStream.Write(requestBody);
                  }
              }

              if (headers != null)
              {
                  if (headers.Keys.Any(p => p.ToLower() == "content-type"))
                      req.ContentType = headers.SingleOrDefault(p => p.Key.ToLower() == "content-type").Value;
                  if (headers.Keys.Any(p => p.ToLower() == "accept"))
                      req.Accept = headers.SingleOrDefault(p => p.Key.ToLower() == "accept").Value;
              }

              var response = (HttpWebResponse)req.GetResponse();

              using(Stream stream = response.GetResponseStream())
              {
                  using (StreamReader reader = new StreamReader(stream, Encoding.GetEncoding("UTF-8")))
                  {
                      resuleJson = reader.ReadToEnd();
                  }
              }
          }
          catch (Exception ex)
          {
              return default(T);
          }
          return JsonConvert.DeserializeObject<T>(resuleJson);
      }

这样即可正确发送 Json 数据。

关于C#通过HttpWebRequest发送带有JSON Body的POST请求实现的文章就介绍至此，更多相关C# post请求 HttpWebRequest内容请搜索编程宝库以前的文章，希望大家多多支持编程宝库！

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