namespace ServiceByAsynchronous {

    delegate void SetContentCallback(string text);
    delegate void AddListViewItemCallback(ListViewItem li);
    /// <summary>
    /// author linzhenchong
    /// date 2009-3-8
    /// </summary>
    public partial class FrmServiceAsyn : Form {
        public FrmServiceAsyn() {
            InitializeComponent();
        }
        //use this event to notify one or more waiting threads that an event has occurred 
        ManualResetEvent manualResetEvent = new ManualResetEvent(false);
        byte[] buffer = new byte[1024 * 1024];//a buffer , used to store the data read from netWorkStream 
        /// <summary>
        /// begin a new connection by asynchronous
        /// </summary>
        /// <param name="listener"></param>
        private void DoBeginAcceptTcpClient(TcpListener listener) {
            manualResetEvent.Reset();//put the current thread in a non-signaled state
            listener.BeginAcceptTcpClient(new AsyncCallback(this.DoAcceptTcpClientCallback), listener);
            manualResetEvent.WaitOne();//block the current thread,and awaiting the signal
        }
        /// <summary>
        /// when a new connection is connected
        /// </summary>
        /// <param name="ar">a asynchronous result which contains some information of the connection</param>
        private void DoAcceptTcpClientCallback(IAsyncResult ar) {
            TcpListener listener = ar.AsyncState as TcpListener;
            TcpClient tcpClient = listener.EndAcceptTcpClient(ar);            
            NetworkStream netStream = tcpClient.GetStream();
            string remoteIp = tcpClient.Client.RemoteEndPoint.ToString();

            ListViewItem li = new ListViewItem(remoteIp);
            li.Tag = netStream;
            this.AddListViewItem(li);

            //add a new listener,so we can accept a new connection
            listener.BeginAcceptTcpClient(new AsyncCallback(this.DoAcceptTcpClientCallback), listener);

            string receive = string.Empty;
            //receive data 
            netStream.BeginRead(buffer, 0, buffer.Length, new AsyncCallback(DoReceiveCallback), netStream);
        }

        private void DoReceiveCallback(IAsyncResult ar) {
            NetworkStream netStream = ar.AsyncState as NetworkStream;
            if (netStream == null) {
                return;
            }
            int count=0;
            try {
                count = netStream.EndRead(ar);
                netStream.BeginRead(buffer, 0, buffer.Length, new AsyncCallback(DoReceiveCallback), netStream);
            }
            catch { }

            string msg = System.Text.Encoding.Default.GetString(buffer, 0, count);
            this.SetContent(msg);
            
            manualResetEvent.Set();//signal the current thread,so that the waiting threads can proceed 
        }

        private void BeginListen() {
            IPAddress ip = IPAddress.Parse("127.0.0.1");
            TcpListener listener = new TcpListener(ip, int.Parse(this.txtPort.Text));
            listener.Start();
            DoBeginAcceptTcpClient(listener);
        }

        private void SetContent(string text) {
            //if current thread have accessed the  "txtContent" control more than one times,
            //or the control is made by current thread, we can access it direct,
            //else we must access it by delegate
            if (this.txtContent.InvokeRequired) {
                SetContentCallback setContentCallback = new SetContentCallback(this.SetContent);
                this.Invoke(setContentCallback, new object[] { text });
            }
            else {
                this.txtContent.Text += text + "/r/n";
            }
        }

        private void AddListViewItem(ListViewItem li) {
            if (this.lvConnectedIp.InvokeRequired) {
                AddListViewItemCallback a = new AddListViewItemCallback(this.AddListViewItem);
                this.Invoke(a, new object[] { li });
            }
            else {
                this.lvConnectedIp.Items.Add(li);
            }
        }

        private void FrmServiceAsyn_Load(object sender, EventArgs e) {
            Thread t = new Thread(new ThreadStart(this.BeginListen));
            t.Start();
        }

        private void btnSend_Click(object sender, EventArgs e) {
            if (this.lvConnectedIp.SelectedItems.Count==0) {
                MessageBox.Show("请选择你要发送的IP");
                return;
            }
            NetworkStream netStream = this.lvConnectedIp.SelectedItems[0].Tag as NetworkStream;
            if (netStream==null) {
                MessageBox.Show("你要发送的链接不存在，可能连接已经关闭多连接出现异常，请重新选择新的连接");
                return;
            }
            byte[] msg =System.Text.Encoding.Default.GetBytes(this.txtMsg.Text);
            netStream.BeginWrite(msg,0,msg.Length,new AsyncCallback(this.DoBeginWriteCallback),netStream);
        }

        private void DoBeginWriteCallback(IAsyncResult ar) {
            NetworkStream netStream = ar.AsyncState as NetworkStream;
            netStream.EndWrite(ar);
        }
    }
}

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