var javaScriptSerializer = new JavaScriptSerializer();
var accessDictionary = javaScriptSerializer.Deserialize<Dictionary<string, object>>(responseData);
先把dll文件加到lib文件夹里面
浏览-》找到dll文件，添加引用。
找dll文件：C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.0-》System.Runtime.Serialization.dll