How to get data from JSON in wp7

考虑这个JSON:

    resourceSets: [
{
estimatedTotal: 5,
resources: [
{
__type: "Location:http://schemas.microsoft.com/search/local/ws/rest/v1",
bbox: [
51.3014406,
-8.3233626,
51.3037489,
-8.3182203
],
name: "Some Address",
point: {
type: "Point",
coordinates: [
51.3033847,
-2.3204335
]
},
address: {
addressLine: "SomeAddress",
adminDistrict: "MI",
adminDistrict2: "South Country",
countryRegion: "England",
formattedAddress: "Some Formattedaddress",
locality: "Derby",
postalCode: "12345"
},

等等。。

紧随其后：http://blog.clauskonrad.net/2010/11/wp7-how-to-consume-json-data-from.html

我的课是：

[DataContract]
public class ReturnedDetails
{
    [DataMember(Name="formattedAddress")]
    public string formattedAddress { get; set; }
}

事件代码：

    void wc_DownloadStringCompleted(object sender, DownloadStringCompletedEventArgs e)
    {
        using (var ms = new system.IO.MemoryStream(Encoding.Unicode.GetBytes(e.Result)))
        {
            var ser = new DataContractJsonSerializer(typeof(ReturnedDetails[]));
            ReturnedDetails[] obj = (ReturnedDetails[])ser.ReadObject(ms);
        }
    }

当我运行这个时，InvalidCastException被抛出到ReturnedDetails[] obj = (ReturnedDetails[])ser.ReadObject(ms);

当我调试并将鼠标悬停在ser上时，KnownDataContracts为"无法计算表达式"answers"null"。

我只想从JSON中的formattedAddress中获取值，有人知道怎么做吗？

谢谢你的帮助。

堆栈跟踪为：

在PhoneApp1.MainPage.wc_DownloadStringCompleted（对象发送方，在下载StringCompletedEventArgs e）System.Net.WebClient.OnDownloadStringCompleted（DownloadStringCompletedEventArgse） 位于System.Net.WebClient.DownloadStringOperationCompleted（对象arg）System.Reflection.RuntimeMethodInfo.InteralInvoke（RuntimeMethodInfortmi，Object obj，BindingFlags invokeAttr，Binder Binder，Object参数，CultureInfo区域性，布尔值isBinderDefault，程序集caller，Boolean verifyAccess，StackCrawlMark&stackMark）System.Reflection.RuntimeMethodInfo.InteralInvoke（对象obj，BindingFlags invokeAttr，Binder Binder，Object[]参数，CultureInfo文化，StackCrawlMark&stackMark）System.Reflection.MethodBase.Invoke（Object obj，Object[]参数）
位于的System.Delegate.DynamicInvokeOne（Object[]args）位于的System.MulticastDelegate.DynamicInvokeImpl（Object[]args）位于的System.Delegate.DynamicInvoke（Object[]args）位于的System.Windows.Threading.DispatcherOperation.IInvoke（）System.Windows.Threading.Dispatcher.Dispatcher（DispatcherPriority优先级）（对象上下文）在System.Windows.Hosting.CallbackCookie.Invoke（Object[]args）System.Windows.Hosting.DelegateWrapper.InternalInvoke（Object[]args）
位于System.Windows.RuntimeHost.ManagedHost.IInvokeDelegate（IntPtrpHandle，Int32 nParamCount，ScriptParam[]pParams，ScriptParam&pResult）

WebResponse ws = req.GetResponse();
//Deserialize the JSON
DataContractJsonSerializer ds = new DataContractJsonSerializer(typeof(RootObject));
//Cast to root object
RootObject ro = (RootObject)ds.ReadObject(ws.GetResponseStream());