关于socket异步的问题
根据MSDN上的例子改过,代码如下:

SocketListener.cs

using System;
using System.Collections.Generic;
using System.Text;
using System.Collections;
using System.Windows.Forms;
using System.Data;
using System.Configuration;
using System.Data.SqlClient;
using System.Net;
using System.Net.Sockets;
using System.Threading;

namespace PDAserver
{
public class StateObject
{
// Client socket.
public Socket workSocket = null;
// Size of receive buffer.
public const int BufferSize = 1024;
// Receive buffer.
public byte[] buffer = new byte[BufferSize];
// Received data string.
public StringBuilder sb = new StringBuilder();
}

public class SocketListener
{
// Thread signal.
public static ManualResetEvent allDone = new ManualResetEvent(false);
public String content;

public SocketListener()
{
}

public void StartListening()
{
// Data buffer for incoming data.
byte[] bytes = new Byte[1024];
//
IPAddress ipAddress = IPAddress.Parse("127.0.0.1");
IPEndPoint localEndPoint = new IPEndPoint(ipAddress, 18600);

// Create a TCP/IP socket.
Socket listener = new Socket(AddressFamily.InterNetwork,
SocketType.Stream, ProtocolType.Tcp);

// Bind the socket to the local endpoint and listen for incoming connections.
try
{
listener.Bind(localEndPoint);
listener.Listen(100);

while (true)
{
// Set the event to nonsignaled state.
allDone.Reset();

// Start an asynchronous socket to listen for connections.
Console.WriteLine("Waiting for a connection...");
listener.BeginAccept(
new AsyncCallback(AcceptCallback),
listener);

// Wait until a connection is made before continuing.
allDone.WaitOne();
}

}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}

Console.WriteLine("\nPress ENTER to continue...");
Console.Read();

}

public void AcceptCallback(IAsyncResult ar)
{
// Signal the main thread to continue.
allDone.Set();

// Get the socket that handles the client request.
Socket listener = (Socket)ar.AsyncState;
Socket handler = listener.EndAccept(ar);

// Create the state object.
StateObject state = new StateObject();
state.workSocket = handler;
handler.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
new AsyncCallback(ReadCallback), state);
}

public void ReadCallback(IAsyncResult ar)
{
//content = String.Empty;

// Retrieve the state object and the handler socket

// from the asynchronous state object.
StateObject state = (StateObject)ar.AsyncState;
Socket handler = state.workSocket;

//结束本次接收并返回接收到的数据长度
int bytesRead = handler.EndReceive(ar);

if (bytesRead > 0)
{
content = System.Text.Encoding.Default.GetString(state.buffer, 0, bytesRead);
string[] arr = content.Split('\\');
string pdaid = arr[1];
Send(handler, pdaid);

//if (content.IndexOf("<EOF>") > -1)
//{
// // All the data has been read from the
// // client. Display it on the console.
// Console.WriteLine("Read {0} bytes from socket. \n Data : {1}",
// content.Length, content);
// //将接收到的数据返回客户端
// Send(handler, content);
//}
//else
//{
// // Not all data received. Get more.
// handler.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
// new AsyncCallback(ReadCallback), state);
//}
}
}

private void Send(Socket handler, String data)
{
// Convert the string data to byte data using ASCII encoding.
byte[] byteData = Encoding.ASCII.GetBytes(data);

// Begin sending the data to the remote device.
handler.BeginSend(byteData, 0, byteData.Length, 0,
new AsyncCallback(SendCallback), handler);
}

private void SendCallback(IAsyncResult ar)
{
try
{
// Retrieve the socket from the state object.
Socket handler = (Socket)ar.AsyncState;

// Complete sending the data to the remote device.
int bytesSent = handler.EndSend(ar);
Console.WriteLine("Sent {0} bytes to client.", bytesSent);

handler.Shutdown(SocketShutdown.Both);
handler.Close();

}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
}
}
}

**********************************************************************************

PdaserverForm.cs

SocketListener tc = new SocketListener();
myThread = new Thread(new ThreadStart(tc.StartListening));
myThread.Start();
rtfTake.Text = tc.content;
btnStart.Enabled = false;




我在SocketListener.cs中声明了一个string content,在PdaserverForm.cs中调用它 rtfTake.Text = tc.content;
可是rtfTake文本框却怎么也取不到值,请高手指教!

[解决办法]
你的异步Socket还没返回你就把tc.Content赋给rtfTake.Text了吧

你可以在你的SocketListener里面声明一个even, 当异步Socket有东西回来, 并且赋给了Content后就Raise up, 然后在你的pdaserverForm里面接到这个事件时,再做rtfTake.Text的赋值动作
[解决办法]
if (bytesRead > 0)
{
content = System.Text.Encoding.Default.GetString(state.buffer, 0, bytesRead);

//这里你收到Message, 就在这里抛出一个even, 通知其他程序去接收Content

string[] arr = content.Split( '\\ ');
string pdaid = arr[1];
Send(handler, pdaid);
}
[解决办法]
还有问题, 参考下我写的这个异步Socket吧

http://blog.csdn.net/LeoMaya/archive/2007/08/06/1728518.aspx
[解决办法]
有异常吗？
异步操作中很可能要用Form.Invoke()通过主线程来修改界面上控件的值