晚上学习时公司的同事，暂且叫A吧，A：“我们公司XXX纺织的AM接口不通，让我看下”，我：“接口写的不是有AJAX异步请求的示例嘛，参考下，我都测试过接口，都是通的。”，A：“我走的不是AJAX，走的CS端”，我：“哦，明白了，CS端的HttpWebRequest模拟前端的AJAX请求，我之前写过一次，我写个DEMO调试看看”

排查结果如下

错误示例，因为CS没法前面加前缀：jsonData

正确的AJAX示例，前面有jsonData(因为后台获取的是jsonData中的数据，CS端这个没法传)

网上找了半天解决方法，我们可以使用上下文，获取JSON数据流，然后在将流还原回JSON字符串即可

1             Stream s = HttpContext.Current.Request.InputStream;//获得json 字符流
2             //还原数据流
3             byte[] b = new byte[s.Length];
4             s.Read(b, 0, (int)s.Length);
5             string jsontext = Encoding.UTF8.GetString(b); //JSON字符串

cs端HttpWebRequest示例

 1         private void button1_Click(object sender, EventArgs e)
 2         {
 3             string res = PostWebRequest("http://XXXXXXX/webService/eCimsService.asmx/GetHullParts", "{\"ProjNo\":\"H001\",\"SectionNo\":\"C002\",Data:[]}", Encoding.UTF8);
 4         }
 5         /// <summary>
 6         /// Post数据接口
 7         /// </summary>
 8         /// <param name="postUrl">接口地址</param>
 9         /// <param name="paramData">提交json数据</param>
10         /// <param name="dataEncode">编码方式(Encoding.UTF8)</param>
11         /// <returns></returns>
12         private static string PostWebRequest(string postUrl, string paramData, Encoding dataEncode)
13         {
14             string responseContent = string.Empty;
15             try
16             {
17                 byte[] byteArray = dataEncode.GetBytes(paramData); //转化
18                 HttpWebRequest webReq = (HttpWebRequest)WebRequest.Create(new Uri(postUrl));
19                 webReq.Method = "POST";
20                 webReq.ContentType = "application/x-www-form-urlencoded; charset=UTF-8";
21                 webReq.Accept = "*/*"; //注：调试的过程中，报415，这里可能需要修改下
22                 webReq.UserAgent = "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36";
23                 webReq.ContentLength = byteArray.Length;
24                 using (Stream reqStream = webReq.GetRequestStream())
25                 {
26                     reqStream.Write(byteArray, 0, byteArray.Length);//写入参数
27                     //reqStream.Close();
28                 }
29                 using (HttpWebResponse response = (HttpWebResponse)webReq.GetResponse())
30                 {
31                     using (Stream myResponseStream = response.GetResponseStream())
32                     {
33                         using (StreamReader myStreamReader = new StreamReader(myResponseStream, Encoding.UTF8))
34                         {
35                             responseContent = myStreamReader.ReadToEnd().ToString();
36                         }
37                     }
38                 }
39             }
40             catch (Exception ex)
41             {
42                 return ex.Message;
43             }
44             return responseContent;
45         }