C＃NullReferenceException由JSON打印

Question

我有一些JSON打印NullReferenceException的問題。我想解析動態創建的JSON代碼，並寫出它們的值。

這是我想System.Json(Object.Parse)解析爲例JSON（這些JSONs是由PHP代碼創建的，它並不總是六個項目長，「DB」給出了列表的大小）：

---

{ 
    "crossclouds": { 
     "files": { 
      "db":"6", 
      "a1": { 
       "name": "list.txt", 
       "id": "2", 
       "size": "0", 
       "modif": "2012-05-17 23:10:33", 
       "given": "3vdcl7WXo5I0m9rcXontHEIQgf661JXS.txt", 
       "sec": "6To92mE15BO7", 
       "mappa": "/" 
      }, 

      "a2": { 
       "name": "hexa2.png", 
       "id": "3", 
       "size": "0", 
       "modif": "2012-05-17 23:10:33", 
       "given": "Z87L6f84XUEtLVJ53g0T7ifYnnJ47UmE.png", 
       "sec": "iKX2bL9UsU98", 
       "mappa": "/" 
      }, 

      .... 

      "a6": { 
       "name": "kristof.txt", 
       "id": "24", 
       "size": "127", 
       "modif": "2012-05-17 23:10:33", 
       "given": "Ze5U3oi59CrkI4xTXLjUP07rilVa0jbS.txt", 
       "sec": "h25yaL8207n6", 
       "mappa": "/" 
      } 
     } 
    } 
} 

所以我想用一個for循環得到從a1到a6的所有值。我試過這個代碼（還有其他的東西），但它不起作用。我得到：

Microsoft.CSharp.RuntimeBinder.RuntimeBinderException - >無法執行運行時的空引用

或

「的NullReferenceException」 結合 - >對象引用不設置到對象的實例。

using System; 
using System.Collections.Generic; 
using System.Linq; 
using System.Text; 
using System.Net; 
//using Newtonsoft.Json; 
using System.Json; 
using System.IO; 
using System.Reflection; 

namespace cc3 
{ 
    class Program 
    { 
     static void Main(string[] args) 
     { 
      Console.Write("Username: "); 
      string user = Console.ReadLine(); 
      Console.Write("Password: "); 
      string pass = Console.ReadLine(); 

      CookieContainer cookies = new CookieContainer(); 
      ServicePointManager.Expect100Continue = false; 
      HttpWebRequest httpWReq = (HttpWebRequest)WebRequest.Create("http://XXXXX/fafa.php"); 
      ASCIIEncoding encoding = new ASCIIEncoding(); 
      string postData = "user=" + user; 
      postData += "&psw=" + pass; 
      byte[] data = encoding.GetBytes(postData); 

      httpWReq.CookieContainer = cookies; 

      httpWReq.Method = "POST"; 
      httpWReq.ContentType = "application/x-www-form-urlencoded"; 
      httpWReq.ContentLength = data.Length; 

      using (Stream newStream = httpWReq.GetRequestStream()) 
      { 
       newStream.Write(data, 0, data.Length); 
       newStream.Close(); 
       WebResponse response = httpWReq.GetResponse(); 
       Console.WriteLine(((HttpWebResponse)response).StatusDescription); 
       Stream newStream2 = response.GetResponseStream(); 
       StreamReader reader = new StreamReader(newStream2); 
       string responseFromServer = reader.ReadToEnd(); 
       responseFromServer = responseFromServer.Replace("\n", ""); 
       responseFromServer = responseFromServer.Replace("\r", ""); 
       responseFromServer = responseFromServer.Replace("\t", ""); 

       dynamic json = JsonValue.Parse(responseFromServer); 

       Console.WriteLine(json.crossclouds.files.db); 
       string db = json.crossclouds.files.db; 
       db = db.Replace("\"", ""); 

       Console.WriteLine(json["db"]); 

       for (int i = 1; i <= Convert.ToInt16(db); i++) 
       { 
        string av = "a" + Convert.ToString(i); 
        object av2 = Convert.ToString("json.crossclouds.files." + av); 
        object r1 = (av2).GetType().GetProperty("name").GetValue(av2, null); 

        if (r1 == null) 
        { 
         Console.WriteLine("Unknown"); 
        } 
        else 
        { 
         Console.WriteLine(r1); 
        } 
       } 
      } 
      reader.Close(); 
      newStream2.Close(); 
      response.Close(); 
     } 
     Console.ReadLine(); 
    } 

我能做些什麼？

Answer 1

我已經做了:)我改變了JSON數據爲「文件」：[{「Name」：「ABC」，等等......並應用了foreach循環 -