windows phone 中HttpWebRequest非同步線程同步

public class RequestState    {        public HttpWebRequest request { get; set; }        public HttpWebResponse response { get; set; }        public Stream streamResponse { get; set; }    }    public class HttpHelper    {        public delegate void GetData(string text);        public event GetData Data;        public class HttpCallBackEvent        {            public HttpWebRequest request;            public byte[] file;            public string name;            public string fileName;        }        public static ManualResetEvent allDone = new ManualResetEvent(false);        public Stream HttpGet(string url )        {            HttpWebRequest request = (HttpWebRequest)WebRequest.Create(new Uri(url));            request.Method = "GET";            RequestState state = new RequestState();            state.request = request;            request.BeginGetResponse(webResponseCallack,state);            allDone.Reset();            allDone.WaitOne();            return state.streamResponse;        }        private void webResponseCallack(IAsyncResult result)        {            try            {                RequestState state = (RequestState)result.AsyncState;                HttpWebRequest request = state.request;                state.response = (HttpWebResponse)request.EndGetResponse(result);                state.streamResponse = state.response.GetResponseStream();                            }            catch            { }            finally            {                allDone.Set();            }        }

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