gistfile1.cs

protected async Task<IEnumerable<byte>> CreateMultipartFormData(IDictionary<string, object> parameter, string boundary)
{
	var dataBytes = new List<byte>();

	foreach (var p in parameter)
	{
		dataBytes.AddRange(Encoding.UTF8.GetBytes("--" + boundary + "\r\n"));

		if (p.Value is Stream)
		{

			var sendData = await Task.Factory.StartNew<byte[]>(() =>
			{
				var ms = p.Value as MemoryStream;
				// ストリームをバイト配列にする
				ms.Seek(0, SeekOrigin.Begin);

				var send = new List<byte>();
				while (true)
				{
					var rb = new byte[1024];
					var readBytes = ms.Read(rb, 0, rb.Length);
					if (readBytes <= 0)
						break;

					send.AddRange(rb);
				}

				return send.ToArray();
			});

			var data = string.Format(
									"Content-Disposition: form-data; name=\"{0}\"; filename=\"upload_{1}.jpg\"\r\n" +
									"Content-Type: application/octet-stream\r\n" +
									"Content-Transfer-Encoding: binary\r\n\r\n", p.Key, boundary);
			dataBytes.AddRange(Encoding.UTF8.GetBytes(data));
			dataBytes.AddRange(sendData);
			dataBytes.AddRange(Encoding.UTF8.GetBytes("\r\n"));
		}
		else if (p.Value is string)
		{
			var data = string.Format(
				"Content-Disposition: form-data; name=\"{0}\"\r\n\r\n" +
				"{1}\r\n", p.Key, (p.Value as string).UrlEncode());

			dataBytes.AddRange(Encoding.UTF8.GetBytes(data));
		}
		else
		{
			var data = string.Format(
				"Content-Disposition: form-data; name=\"{0}\"\r\n\r\n" +
				"{1}\r\n", p.Key, p.Value);

			dataBytes.AddRange(Encoding.UTF8.GetBytes(data));
		}
	}

	dataBytes.AddRange(Encoding.UTF8.GetBytes("--" + boundary + "--"));
	return dataBytes;
}