httplistener.cs

// Chạy một HTTP Server, prefixes example: new string[] { "http://*:8080/" }
class MyHttpServer 
{
    private HttpListener listener;

    public MyHttpServer(params string[] prefixes)
    {
        if (!HttpListener.IsSupported) 
            throw new Exception ("Máy không hỗ trợ HttpListener.");

        if (prefixes == null || prefixes.Length == 0)
            throw new ArgumentException ("prefixes");

        // Khởi tạo HttpListener
        listener = new HttpListener ();
        foreach (string prefix in prefixes) 
            listener.Prefixes.Add(prefix);

    }
    public async Task StartAsync()
    {
        // Bắt đầu lắng nghe kết nối HTTP
        listener.Start();
        do 
        {

            try 
            {
                Console.WriteLine($"{DateTime.Now.ToLongTimeString()} : waiting a client connect");

                // Một client kết nối đến
                HttpListenerContext context = await listener.GetContextAsync();
                await ProcessRequest(context);

            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
            }
            Console.WriteLine("...");

        }
        while (listener.IsListening);
    }

    // Xử lý trả về nội dung tùy thuộc vào URL truy cập
    //      /               hiện thị dòng Hello World
    //      /stop           dừng máy chủ
    //      /json           trả về một nội dung json
    //      /anh2.png       trả về một file ảnh 
    //      /requestinfo    thông tin truy vấn
    async Task ProcessRequest(HttpListenerContext context)
    {
            HttpListenerRequest  request  = context.Request;
            HttpListenerResponse response = context.Response;
            Console.WriteLine($"{request.HttpMethod} {request.RawUrl} {request.Url.AbsolutePath}");

            // Lấy stream / gửi dữ liệu về cho client
            var outputstream = response.OutputStream;


            switch (request.Url.AbsolutePath)
            {
                case "/requestinfo":
                {
                    // Gửi thông tin về cho Client
                    context.Response.Headers.Add("content-type", "text/html");
                    context.Response.StatusCode = (int) HttpStatusCode.OK;

                    string responseString = this.GenerateHTML(request);
                    byte[] buffer = System.Text.Encoding.UTF8.GetBytes(responseString);
                    response.ContentLength64 = buffer.Length;
                    await outputstream.WriteAsync(buffer,0,buffer.Length);
                }
                break;
                case "/":
                {
                    byte[] buffer = System.Text.Encoding.UTF8.GetBytes("Hello world!");
                    response.ContentLength64 = buffer.Length;
                    await outputstream.WriteAsync(buffer,0,buffer.Length);
                }
                break;

                case "/stop":
                {
                    listener.Stop();
                    Console.WriteLine("stop http");
                }
                break;

                case "/json":
                {
                    response.Headers.Add("Content-Type", "application/json");
                    var product = new {
                        Name = "Macbook Pro",
                        Price = 2000,
                        Manufacturer = "Apple"
                    };
                    string jsonstring =  JsonConvert.SerializeObject(product);
                    byte[] buffer = System.Text.Encoding.UTF8.GetBytes(jsonstring);
                    response.ContentLength64 = buffer.Length;
                    await outputstream.WriteAsync(buffer,0,buffer.Length);

                }
                break;
                case "/anh2.png":
                {
                    response.Headers.Add("Content-Type", "image/png");
                    byte[] buffer = await File.ReadAllBytesAsync("anh2.png");
                    response.ContentLength64 = buffer.Length;
                    await outputstream.WriteAsync(buffer,0,buffer.Length);

                }
                break;

                default:
                {
                    response.StatusCode = (int)HttpStatusCode.NotFound;
                    byte[] buffer = System.Text.Encoding.UTF8.GetBytes("NOT FOUND!");
                    response.ContentLength64 = buffer.Length;
                    await outputstream.WriteAsync(buffer,0,buffer.Length);
                }
                break;
            }

            // switch (request.Url.AbsolutePath)


            // Đóng stream để hoàn thành gửi về client
            outputstream.Close();
    }

    // Tạo nội dung HTML trả về cho Client (HTML chứa thông tin về Request)
    public string GenerateHTML (HttpListenerRequest request) {
        string format = @"<!DOCTYPE html>
                            <html lang=""en""> 
                                <head>
                                    <meta charset=""UTF-8"">
                                    {0}
                                 </head> 
                                <body>
                                    {1}
                                </body> 
                            </html>";
        string head = "<title>Test WebServer</title>";
        var body = new StringBuilder ();
        body.Append ("<h1>Request Info</h1>");
        body.Append ("<h2>Request Header:</h2>");

        // Header infomation
        var headers = from key in request.Headers.AllKeys
        select $"<div>{key} : {string.Join(",", request.Headers.GetValues(key))}</div>";
        body.Append (string.Join ("", headers));

        //Extract request properties
        body.Append ("<h2>Request properties:</h2>");
        var properties = request.GetType ().GetProperties ();
        foreach (var property in properties) {
            var name_pro = property.Name;
            string value_pro;
            try {
                value_pro = property.GetValue (request).ToString ();
            } catch (Exception e) {
                value_pro = e.Message;
            }
            body.Append ($"<div>{name_pro} : {value_pro}</div>");

        };
        string html = string.Format (format, head, body.ToString ());
        return html;
    }


}