全栈工程师开发手册 （作者：栾鹏）
c#教程全解
c#实现ajax通信，通过向服务器后台发送json数据，接收响应数据提交给前台。
其中包含两个主要函数，发送数据，接收响应数据的Http请求响应函数。另一个是将对象转化为JSON字符串的序列化函数。
需要下载并在引用空间中引入Newtonsoft.Json.dll，下载
using Newtonsoft.Json.Linq;using Newtonsoft;using Newtonsoft.Json;/// <summary>/// 向服务器后台发送json数据，需要引入Newtonsoft.Json.dll/// </summary>/// <param name="urlpath">请求地址</param>/// <param name="diclist">json键值对</param>/// <returns></returns>public static JObject ajax(string urlpath, Dictionary<String, String> diclist){HttpWebRequest req = (HttpWebRequest)WebRequest.Create(urlpath);req.Method = "POST";req.ContentType = "application/x-www-form-urlencoded";//设置参数，并进行URL编码//虽然我们需要传递给服务器端的实际参数是JsonParas（格式：[{"UserID":"0206001","username","ceshi"}]）//但是需要将字符串参数构造成键值对的形式，注："paramaters=["userid":"206001","username","ceshi"}]"//其中键paramaters为webservice接口函数的参数名，值为经过序列化的Json数据字符串//最后将字符串参数进行url编码String poststr = buildQueryStr(diclist);byte[] payload = Encoding.UTF8.GetBytes(poststr);req.ContentLength = payload.Length;//发送请求，获得请求流Stream writer;try{writer = req.GetRequestStream(); //获取用于写入请求数据的Stream对象}catch (Exception){writer = null;MessageBox.Show("连接服务器失败");return null;}//将请求参数写入流writer.Write(payload, 0, payload.Length);writer.Close(); //关闭请求流string strvalue = ""; //srevalue为http响应所返回的字符流HttpWebResponse response;try{//获得响应流response = (HttpWebResponse)req.GetResponse();}catch (WebException ex){response = ex.Response as HttpWebResponse;}Stream s = response.GetResponseStream();StreamReader reader = new StreamReader(s);strvalue = reader.ReadToEnd();reader.Close();s.Close();JObject JSONobj = JObject.Parse(strvalue);//lei.ziji = JsonConvert.DeserializeObject<user_me_back>(JSONobj["data".ToString()]); //将字符串转化为类实例return JSONobj;}//将键值对序列转化为请求网址字符串public static String buildQueryStr(Dictionary<String,String> diclist){Dictionary<string, string> dd = new Dictionary<string, string>();dd.Add("key1", "value1");string aa = dd["key1"];string poststr = "";foreach (var item in diclist){poststr += item.Key + "=" + HttpUtility.UrlEncode(item.Value,Encoding.UTF8)+"&";}poststr = poststr.Substring(0, poststr.LastIndexOf("&"));return poststr;}
