新手求助：socket异步监听中怎么跟新窗体控件的信息？
我做了一个简单的socket服务器，监听客户端传来的消息。用的异步操作代码其实我并不是太懂，所以有一些地方很迷惑。我现在最不解的地方就是在ReceiveMessage(IAsyncResult ar)这个方法里面，在这里从客户端获取一些消息，然后根据判断做出回应。同时我还需要在回应的同时更新窗体上richTextBox1里的内容，就是把ReceiveMessage(IAsyncResult ar)方法里的Msg变量的值添加到富文本框中，可是在ReceiveMessage(IAsyncResult ar)方法中richTextBox1竟然不存在。。。。郁闷，求指教。。

C# code

using System;using System.Collections.Generic;using System.ComponentModel;using System.Data;using System.Drawing;using System.Linq;using System.Text;using System.Net;using System.Net.Sockets;using System.Windows.Forms;namespace tcp服务器{    public partial class Form1 : Form    {        public Form1()        {            InitializeComponent();        }        static string Msg=null;        private void button1_Click(object sender, EventArgs e)        {            var socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);            //将该socket绑定到主机上面的某个端口            socket.Bind(new IPEndPoint(IPAddress.Any, 8888));            //启动监听，并且设置一个最大的队列长度            socket.Listen(10);            richTextBox1.AppendText("Server is Lincening!");            //开始接受客户端连接请求                                       socket.BeginAccept(new AsyncCallback(ClientAccepted), socket);                                if (Msg != null)                {                    richTextBox1.AppendText(Msg);                    Msg = null;                }        }        public static void ClientAccepted(IAsyncResult ar)        {            var socket = ar.AsyncState as Socket;            //这就是客户端的Socket实例，我们后续可以将其保存起来            var client = socket.EndAccept(ar);            //接收客户端的消息(这个和在客户端实现的方式是一样的）            client.BeginReceive(buffer, 0, buffer.Length, SocketFlags.None, new AsyncCallback(ReceiveMessage), client);                        //准备接受下一个客户端请求            socket.BeginAccept(new AsyncCallback(ClientAccepted), socket);        }        static byte[] buffer = new byte[1024];        public static void ReceiveMessage(IAsyncResult ar)        {            try            {                var socket = ar.AsyncState as Socket;                var length = socket.EndReceive(ar);                //读取出来消息内容                var message = Encoding.Unicode.GetString(buffer, 0, length);                //显示消息                //Console.WriteLine(message);                string strFlog = message.Substring(0, 1);                switch (int.Parse(strFlog))                {                    case 0:             //如果首字符为0,                        {                            socket.Send(Encoding.Unicode.GetBytes("{asdasd,asd}"));                        } break;                    case 1:                        {                            string megcontent = message.Substring(1, message.Length - 1);                            Msg = megcontent + " 测试一在线......"+strFlog;//!                        } break;                    case 2:                        {                            string megcontent = message.Substring(1, message.Length - 1);                            Msg = megcontent + " 测试2在线......"+strFlog;//!                        } break;                    default: Msg = "无效信息"; break;//!                }                socket.BeginReceive(buffer, 0, buffer.Length, SocketFlags.None, new AsyncCallback(ReceiveMessage), socket);                    }            catch (Exception ex)            {                Console.WriteLine(ex.Message);            }                   }     }}

[解决办法]
//3楼的委托忘记初始化了，应该是这样
//异步委托调用主线程的显示方法，回到UI主线程。
//先写个方法用于在窗体显示信息
public void ShowMsg(string msg)
{
? MessageBox.Show(msg);
}
//声明委托
delegate void mydelegate(string msg);

//在你的异步方法ReceiveMessage里调用主界面委托的方法
Form1.CheckForIllegalCrossThreadCalls = false;
Form1.BeginInvok(new mydelegate(Form1.ShowMsg),new object[]{"你要显示的信息"});