Post Operation for Windows 8 Apps || Windows Phone

简单实现HTTP Post & Get 请求操作， post 可用于文件或表单。此类适用于Windows 8 Apps 和 Windows phone.

    /// <summary>
    /// Use for HTTP Post Method: send simple data or file
    /// </summary>
    public class HttpPostHelper
    {
        public void PostData(string postUrl, IDictionary<string, object> parameters)
        {
            string formDataBoundary = "-----------------------------525258000";
            string contentType = "multipart/form-data;boundary=" + formDataBoundary;

            _formData = GetFormData(parameters, formDataBoundary);
            ExcutePostRequest(postUrl, contentType);
        }

        private void ExcutePostRequest(string postUrl, string contentType)
        {
            var request = WebRequest.Create(postUrl) as HttpWebRequest;

            if (request == null)
            {
                Debug.WriteLine("Request is not a request.");
            }

            request.Method = "POST";
            request.ContentType = contentType;
            request.BeginGetRequestStream(RequestReady, request);
        }

        private void RequestReady(IAsyncResult asyncResult)
        {
            var request = asyncResult.AsyncState as HttpWebRequest;

            if (request == null) return;
            using (Stream requestStream = request.EndGetRequestStream(asyncResult))
            {
                requestStream.Write(_formData, 0, _formData.Length);
            }

            request.BeginGetResponse(ResponseReady, request);
        }

        private void ResponseReady(IAsyncResult asyncResult)
        {
            var request = asyncResult.AsyncState as HttpWebRequest;

            try
            {
                var response = (HttpWebResponse) request.EndGetResponse(asyncResult);
                string result;
                using (var responseStream = response.GetResponseStream())
                {
                    using (var reader = new StreamReader(responseStream))
                    {
                        result = reader.ReadToEnd();
                    }
                }

                if (DownloadStringCompleted != null)
                {
                    DownloadStringCompleted(this, new DownloadStringCompletedEventArgs(result));
                }
            }
            catch
            {
                if (DownloadStringCompleted != null)
                {
                    DownloadStringCompleted(this,
                                            new DownloadStringCompletedEventArgs(
                                                new Exception("Error getting HTTP web response.")));
                }
            }
        }

        private static byte[] GetFormData(IEnumerable<KeyValuePair<string, object>> parameters, string boundary)
        {
            Stream formDataStream = new MemoryStream();
            var encoding = Encoding.UTF8;
            foreach (var param in parameters)
            {
                if (param.Value is byte[])
                {
                    var fileData = param.Value as byte[];

                    string header =
                        string.Format(
                            "--{0}\r\nContent-Disposition:form-data;name=\"file\";filename=\"{1}\";\r\nContent-Type:application/zip\r\n\r\n",
                            boundary, param.Key);
                    formDataStream.Write(encoding.GetBytes(header), 0, header.Length);
                    formDataStream.Write(fileData, 0, fileData.Length);
                }
                else
                {
                    string postData = string.Format(
                        "--{0}\r\nContent-Disposition:form-data;name=\"{1}\"\r\n\r\n{2}\r\n", boundary, param.Key,
                        param.Value);
                    formDataStream.Write(encoding.GetBytes(postData), 0, postData.Length);
                }
            }
            string footer = "\r\n--" + boundary + "--\r\n";
            formDataStream.Write(encoding.GetBytes(footer), 0, footer.Length);

            formDataStream.Position = 0;
            var formData = new byte[formDataStream.Length];
            formDataStream.Read(formData, 0, formData.Length);
            formDataStream.Dispose();

            return formData;
        }

        public delegate void DownloadStringCompletedHandler(object sender, DownloadStringCompletedEventArgs e);

        public event DownloadStringCompletedHandler DownloadStringCompleted;

        private byte[] _formData = null;
    }

    /// <summary>
    /// Use for HTTP Get Method 
    /// </summary>
    public class HttpGetHelper
    {
        public void ExecuteGetReuqest(string url)
        {
            var request = WebRequest.Create(url) as HttpWebRequest;

            if (request == null)
            {
                Debug.WriteLine("Request is not a request.");
            }
            else
            {
                request.BeginGetResponse(ResponseReady, request);
            }
        }

        private void ResponseReady(IAsyncResult asyncResult)
        {
            try
            {
                var request = (HttpWebRequest) asyncResult.AsyncState;
                var response = (HttpWebResponse) request.EndGetResponse(asyncResult);
                string result;
                using (var responseStream = response.GetResponseStream())
                {
                    using (var reader = new StreamReader(responseStream))
                    {
                        result = reader.ReadToEnd();
                    }
                }

                if (DownloadStringCompleted != null)
                {
                    DownloadStringCompleted(this, new DownloadStringCompletedEventArgs(result));
                }
            }
            catch
            {
                if (DownloadStringCompleted != null)
                {
                    DownloadStringCompleted(this,
                                            new DownloadStringCompletedEventArgs(
                                                new Exception("Error getting HTTP web response.")));
                }
            }
        }

        public delegate void DownloadStringCompletedHandler(object sender, DownloadStringCompletedEventArgs e);

        public event DownloadStringCompletedHandler DownloadStringCompleted;
    }

    public class DownloadStringCompletedEventArgs : EventArgs
    {
        public DownloadStringCompletedEventArgs(string result)
        {
            Result = result;
        }

        public DownloadStringCompletedEventArgs(Exception ex)
        {
            Error = ex;
        }

        public string Result { get; private set; }
        public Exception Error { get; private set; }
    }