HttpWebRequest POST請求webapi：如果引數是簡單型別，比如字串（注意，拼接的字串要HttpUtility.UrlEncode才行，否則服務端會丟失特殊字元&後面的資料）

要點：如下程式碼統一設定為：ContentType = "application/x-www-form-urlencoded";

服務端程式碼1：URL格式為 POSTapi/Values

public string Post([FromBody] string value)

則客戶端Post的資料：拼接的字串必須以 =開頭，否則服務端無法取得value。例如：=rfwreewr2332322232 或者 

服務端程式碼2：URL格式為 POST api/Values?value={value}

public string Post(string value)

則客戶端Post的資料：需要url裡拼接出KeyValue這樣的資料

服務端程式碼3：URL格式為 POSTapi/Values

public string Post()

則客戶端Post的資料：無要求。例如：key=rfwreewr2332322232。

服務端：可以用HttpContext.Current.Request.InputStream或者HttpContext.Current.Request.Form[0]都可以獲取

如果post的引數型別比較複雜，則需要自定義類

要點：如下程式碼統一設定為：ContentType = "application/json";

服務端程式碼1：URL格式為 POSTapi/Values

public string Post([FromBody] Model value)或者 public string Post(Model value)

則客戶端Post的資料：{\"id\":\"test1\",\"name\":\"value\"}。服務端會自動對映到物件。

提交程式碼如下：

            HttpWebRequest wReq = (HttpWebRequest)WebRequest.Create("http://localhost:37831/api/Values");
            wReq.Method = "Post";
            //wReq.ContentType = "application/json";
            //wReq.ContentType = "application/x-www-form-urlencoded";
            wReq.ContentType = "application/json";

            //byte[] data = Encoding.Default.GetBytes(HttpUtility.UrlEncode("key=rfwreewr2332322232&261=3&261=4"));
            byte[] data = Encoding.Default.GetBytes("{\"id\":\"test1\",\"name\":\"value\"}");
            wReq.ContentLength = data.Length;
            Stream reqStream = wReq.GetRequestStream();
            reqStream.Write(data, 0, data.Length);
            reqStream.Close();
            using (StreamReader sr = new StreamReader(wReq.GetResponse().GetResponseStream()))
            {
                string result = sr.ReadToEnd();

               
            }
 

        // POST api/values
        //public string Post()
        //{
        //    FileInfo fi = new FileInfo(AppDomain.CurrentDomain.BaseDirectory + "log.txt");
        //    StreamWriter sw = fi.CreateText();
        //    StreamReader sr = new StreamReader(HttpContext.Current.Request.InputStream);
        //    sw.WriteLine("1:" + sr.ReadToEnd()+"--"+ HttpContext.Current.Request.Form[0]);
        //    sw.Flush();
        //    sw.Close();
        //    return "{\"test\":\"1\"}";
        //}

        // POST api/values
        public HttpResponseMessage PostStudent(Student student)
        {
            FileInfo fi = new FileInfo(AppDomain.CurrentDomain.BaseDirectory + "log.txt");
            StreamWriter sw = fi.AppendText();

            sw.WriteLine("2:" + student.id);
            sw.Flush();
            sw.Close();
            HttpResponseMessage result = new HttpResponseMessage { Content = new StringContent("{\"test\":\"2\"}", Encoding.GetEncoding("UTF-8"), "application/json") };
            return result;
        }

這篇文章裡有的方法也不錯：http://www.cnblogs.com/rohelm/p/3207430.html