TCP client in ASP.net | 易学教程

问题

i'm trying to connect from asp web application to tcp server. I did this using application in C#, and now i'd like to see if it will be working from web browser.

My code is:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Net;
using System.Net.Sockets;

namespace TcpWebClient

{
    public partial class _Default : System.Web.UI.Page
{

    private byte[] data = new byte[1024];
    IPEndPoint ipep = new IPEndPoint(
            IPAddress.Parse("192.168.1.20"), 12000);

    Socket server = new Socket(AddressFamily.InterNetwork,
                   SocketType.Stream, ProtocolType.Tcp);


    protected void Page_Load(object sender, EventArgs e)
    {

    }

    protected void Button1_Click(object sender, EventArgs e)
    {

        try
        {
            server.Connect(ipep);
        }
        catch (SocketException)
        {              
        }
    }

    protected void Button2_Click(object sender, EventArgs e)
    {
        NetworkStream ns = new NetworkStream(server);

        if (ns.CanWrite)
        {
            ns.Write(Encoding.ASCII.GetBytes("DI"), 0, 2);
            ns.Flush();
        }
        else
        {
        }
        TextBox1.Text = null;
        TextBox1.Text = Encoding.ASCII.GetString(data, 0, ns.Read(data, 0, data.Length));
    }

}
}

What is working?: I have connection to tcp server. But when i want to send and receive some data i'm getting errors:

IOException was unhandled by user code and something like this: Operation is not supported on connected sockets (don't know if my translation to english is ok).

What i'm doing wrong?

A first chance exception of type 'System.IO.IOException' occurred in System.dll

EDIT:

Something like this is working.. but every tick of timer i need to reconnect to the server.. is it possible to have one connection, then every tick of timer read/send data without reconnecting?

 protected void Timer1_Tick(object sender, EventArgs e)
    {

            server.Connect(ipep);
            NetworkStream stream = new NetworkStream(server);

            Byte[] data = System.Text.Encoding.ASCII.GetBytes("data");
            stream.Write(data, 0, data.Length);
            data = new Byte[256];
            Int32 bytes = stream.Read(data, 0, 8);
            responseData = System.Text.Encoding.ASCII.GetString(data, 0, bytes);
            TextBox1.Text = responseData;
            server.Close();

        }

回答1:

You actually answered yourself: The connection is not openned in your second event handler (Button2_click), because you open on button1 click, and it, of coure ends its lifecycle togethere wit the page, an instance of which is created per request.

You can save the opened connection in a static variable (if you dont mind the connection being shared application - wide for all the users), but i really am not sure you souldnt really just go with the code you posted in your edit.
if you want the connectoin to be availibale application wide, define its variable as a static one (but make sure you initialize / connect before the first attempt to use), You can use the Lazy<T> helper classes provided in .net 4 to make sure the connection is initialized once, only on the first time it is needed.
If you need the connection to be accessible in other classes as well, you can create a seaparate singleton class to wrap it (and initialize it there, in a same way)

来源：https://stackoverflow.com/questions/10935409/tcp-client-in-asp-net

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