Class for easily posting JSON or XML Data in C#

FormPoster

public class FormPoster
	{
		#region Private Variables

		private readonly Dictionary<string, Header> m_HeaderList = new Dictionary<string, Header>();
		private readonly Dictionary<string, Parameter> m_ParameterList = new Dictionary<string, Parameter>();
		private CookieContainer m_CookieContainer = new CookieContainer();
		private string m_RawPostData;

		#endregion

		#region Accessors

		public string Username { get; set; }
		public string Password { get; set; }
		public string Url { get; set; }
		public string ContentType { get; set; }
		public string AcceptType { get; set; }
		public string Method { get; set; }

		#endregion

		#region Constructor

		public FormPoster(string url, string method = null)
		{
			Url = url;
			Method = method ?? "POST";
			ContentType = "application/x-www-form-urlencoded";
		}

		#endregion

		#region Public Helper Methods

		public void AddHeader(string name, object value)
		{
			var header = new Header
			{
				Name = name,
				Value = (value == null) ? null : value.ToString()
			};

			m_HeaderList[name] = header;
		}

		public void AddParameter(string name, object value)
		{
			var parameter = new Parameter
			{
				Name = name,
				Value = (value == null) ? null : value.ToString()
			};

			m_ParameterList[name] = parameter;
		}

		public void SetCookieContainer(CookieContainer cookieContainer)
		{
			m_CookieContainer = cookieContainer;
		}

		public void SetJsonData(object o)
		{
			var serializer = new JavaScriptSerializer();

			SetJsonString(serializer.Serialize(o));
		}

		public void SetJsonString(string s)
		{
			m_RawPostData = s;
			ContentType = "application/json";
		}

		#endregion

		#region Helper Methods

		private string GetPostData()
		{
			if (!string.IsNullOrEmpty(m_RawPostData))
				return m_RawPostData;

			return GetParametersForPosting();
		}

		private string GetParametersForPosting()
		{
			var postData = new StringBuilder();

			foreach (var parameter in m_ParameterList.Values)
			{
				var encodedValue = HttpUtility.UrlEncode(parameter.Value);

				postData.Append(parameter.Name);
				postData.AppendFormat("={0}&", encodedValue);
			}

			var returnVal = postData.ToString();

			if (returnVal.EndsWith("&"))
				returnVal = returnVal.Substring(0, returnVal.Length - 1);

			return returnVal;
		}

		#endregion

		#region Helper Classes

		private struct Header
		{
			/// <summary>
			/// Header Name
			/// </summary>
			public string Name;

			/// <summary>
			/// Header Value
			/// </summary>
			public string Value;
		}

		private struct Parameter
		{
			/// <summary>
			/// Parameter Name
			/// </summary>
			public string Name;

			/// <summary>
			/// Parameter Value
			/// </summary>
			public string Value;
		}

		#endregion

		public void SetBasicAuthHeader(string username, string password)
		{
			var encoded = System.Convert.ToBase64String(Encoding.GetEncoding("ISO-8859-1").GetBytes(username + ":" + password));
			AddHeader("Authorization", "Basic " + encoded);
		}

		/// <summary>
		/// Performs the post and returns the response
		/// </summary>
		public PostResponse Post()
		{
			// Get the parameters string ready for posting
			var postData = GetPostData();

			// Construct the web request
			var webRequest = (HttpWebRequest)WebRequest.Create(Url);
			webRequest.Method = Method;
			webRequest.ContentType = ContentType;
			webRequest.ContentLength = postData.Length;

			if (!string.IsNullOrEmpty(AcceptType))
				webRequest.Accept = AcceptType;

			// Set credentials if required
			if (!string.IsNullOrEmpty(Username) && !string.IsNullOrEmpty(Password))
				webRequest.Credentials = new NetworkCredential(Username, Password);

			// Set the cookie container if required
			if (m_CookieContainer != null)
				webRequest.CookieContainer = m_CookieContainer;

			// Add the headers
			foreach (var header in m_HeaderList.Values)
				webRequest.Headers.Add(header.Name, header.Value);

			// Post the data
			if (postData.Length > 0)
			{
				using (var streamOut = new StreamWriter(webRequest.GetRequestStream(), Encoding.ASCII))
				{
					streamOut.Write(postData);
					streamOut.Close();
				}
			}
			
			var postResponse = new PostResponse();

			// Get the response
			using (var response = webRequest.GetResponse())
			{
				foreach (var header in response.Headers)
				{
					postResponse.Headers[header.ToString()] = response.Headers[header.ToString()];
				}

				using (var rs = response.GetResponseStream())
				{
					if (rs != null)
					{
						using (var streamIn = new StreamReader(rs))
						{
							postResponse.Text = streamIn.ReadToEnd();
							streamIn.Close();
						}
					}
				}
			}

			postResponse.CookieContainer = webRequest.CookieContainer;

			return postResponse;
		}

		public class PostResponse
		{
			public PostResponse()
			{
				Headers = new Dictionary<string, string>();
			}

			public string Text { get; set; }
			public Dictionary<string, string> Headers { get; set; }
			public CookieContainer CookieContainer { get; set; }
		}
	}