关于客户端和服务端聊天室的思路和代码（主要参考传智播客讲课）

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Net.Sockets;
using System.Net;
using System.Threading;
using System.IO;

namespace ItcastSocketTest
{
/// <summary>
/// 基本思路一、关于套接字二、关于线程
/// 1.1、客户端要本地的ip和一个socket相关联--通过socketWatch.Bind(endpoint);完成
/// 1.2、完成关联之后就开始用用“第一线程watchTread” 监听
/// 1.3、监听到客户端之后，服务端会再创建一个负责与客户端通信的socket----socketConnetion
/// 2.1、客户端与服务端的通信都通过socketConnetion来实现 包括send receive
/// 2.2、当服务当接收信息时，要创建一个新的“第二线程recieveTread”，防止冲突
/// 为什么发送不用创建线程
/// 因为发送消息的时间服务器不用对自己监听 当客户端发送消息时， 服务端要对其监听
/// </summary>
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();

TextBox.CheckForIllegalCrossThreadCalls = false;
}
Thread watchTread=null;//创建一个线程，防止线程“死等”事件的发生
Thread recieveTread = null;//创建一个接收线程，
Socket socketWatch=null;//创建一个套接字用来获取服务器的ip和端口
Socket socketConnetion = null;//链接成功后返回一个套接字
Dictionary<string,Socket> dtSocket=new Dictionary<string,Socket>();//创建一个字段，用来实现服务端向多个客户端发送信息
Dictionary<string, Thread> dtThread = new Dictionary<string, Thread>();//创建一个字段，用来实现服务端向多个客户端发送信息
/// <summary>
/// 启动服务端
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void BtnBeginServer_Click(object sender, EventArgs e)
{   //创建服务器线程 负责监听的套接字
socketWatch = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
IPAddress address = IPAddress.Parse(txtIP.Text.ToString());
IPEndPoint endpoint = new IPEndPoint(address, int.Parse(txtPort.Text.Trim()));
//=========================================================
socketWatch.Bind(endpoint);//将负责监听的套接字绑定到指定的ip和端口上
socketWatch.Listen(10);
//=======================================================
//创建监听线程，防止UI线程与监听线程冲突
watchTread = new Thread(WatchConnection);
watchTread.IsBackground = true;
watchTread.Start();

//========================================================
//创建客户端向客户端发送消息进程
//clientToClientThread = new Thread(recieveAndSend);
//clientToClientThread.IsBackground = false;
//clientToClientThread.Start();

MsgShow("服务器监听成功！");
}
/// <summary>
/// 链接服务端
/// </summary>
void WatchConnection()
{
while(true)
{
socketConnetion = socketWatch.Accept();//一旦监听成功将返回一个链接套接字

string strClient = socketConnetion.RemoteEndPoint.ToString();//获取远程客户端的ip和port信息
lbClientList.Items.Add(strClient);
dtSocket.Add(strClient, socketConnetion);
//=======================================================
//创建接收消息进程
recieveTread = new Thread(recievInfo);//当服务端接收消息时会和ui线程冲突，新建线程
recieveTread.IsBackground = false;
recieveTread.Start(socketConnetion);

dtThread.Add(strClient,recieveTread);

MsgShow("连接服务器成功！！" + strClient);

}
}

#region 接受消息委托--recievInfo(Object socketpara)
/// <summary>
/// 接收消息
/// </summary>
void recievInfo(Object socketpara)
{
Socket socketRecieve = socketpara as Socket;
while (true)
{
Byte[] arrMsgRec = new byte[1024 * 1024 * 2]; //用来储存接收服务端的二进制数据
//接收到文件的长度

int length = socketRecieve.Receive(arrMsgRec);//完成了接受传过来的二进制数据，并且返回一个整形数值
if (arrMsgRec[0] == 0)
{
//把接收到的消息转化成string类型
string strMsgRec = System.Text.Encoding.UTF8.GetString(arrMsgRec, 1, length);
MsgShow(strMsgRec);
}
else if (arrMsgRec[0] == 1)
{
SaveFileDialog sfd = new SaveFileDialog();

if (sfd.ShowDialog(this) == DialogResult.OK)
{
string fileSavePath = sfd.FileName;
using (FileStream fs = new FileStream(fileSavePath, FileMode.Create))
{
fs.Write(arrMsgRec, 1, length - 1);
MsgShow("文件已经保存在:" + fileSavePath);
}

}

}

}
}
#endregion
void MsgShow(string str)
{
txtMsg.AppendText(str + "\r\n");
}

private void btnSend_Click(object sender, EventArgs e)
{
string strMsg=txtSend.Text.Trim();
byte[] arrMsg=System.Text.Encoding.UTF8.GetBytes(strMsg);
//====================================================================
//找到选中客户端，让字典中的key值与选中客户端的名字相同，则向他发送消息
string strClient = lbClientList.Text;
dtSocket[strClient].Send(arrMsg);
MsgShow(strMsg + "已发送！");
}

private void btnSendToAll_Click(object sender, EventArgs e)
{
string strMsg = txtSend.Text.Trim();
byte[] arrMsg = System.Text.Encoding.UTF8.GetBytes(strMsg);
foreach (Socket s in dtSocket.Values)
{
s.Send(arrMsg);
}
MsgShow("群发完毕~~");
}
}
}

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Net.Sockets;
using System.Net;
using System.Threading;
using System.IO;
namespace ChatClient
{
public partial class FClient : Form
{
public FClient()
{
InitializeComponent();
//防止出现不运行的txtMsg线程操作
TextBox.CheckForIllegalCrossThreadCalls = false;
}
Socket socketClient;
private void BtnConntionServer_Click(object sender, EventArgs e)
{
socketClient = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
IPAddress address = IPAddress.Parse(txtIP.Text.ToString());
IPEndPoint endpoint = new IPEndPoint(address, int.Parse(txtPort.Text.Trim()));
socketClient.Connect(endpoint);
Thread recThread = new Thread(RecMsg);
recThread.IsBackground = false;//防止在关闭程序后另外一个线程还在进行
recThread.Start();//出现一个实例，一定要让其start 说明是线程可以开始了即就绪了

}
void RecMsg()
{
while(true)
{
Byte[] arrMsgRec = new byte[1024 * 1024 * 2]; //用来储存接收服务端的二进制数据
//接收到文件的长度
int length=socketClient.Receive(arrMsgRec);
//把接收到的消息转化成string类型
string strMsgRec = System.Text.Encoding.UTF8.GetString(arrMsgRec, 0, length);
MsgShow(strMsgRec);
}
}
void MsgShow(string str)
{
txtMsg.AppendText(str + "\r\n");
}

private void btnSend_Click(object sender, EventArgs e)
{//先与主机建立链接，然后让主机产生一个负责通讯的套接字，最终由客户端send，服务端recieve就可以
//socketClient = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
//IPAddress address = IPAddress.Parse(txtIP.Text.ToString());
//IPEndPoint endpoint = new IPEndPoint(address, int.Parse(txtPort.Text.Trim()));
//socketClient.Connect(endpoint);
string msg = this.txtC2S.Text.Trim();
byte[] arrMsg = System.Text.Encoding.UTF8.GetBytes(msg);
byte[] arrMsgSend = new byte[arrMsg.Length + 1];
arrMsgSend[0] = 0;
Buffer.BlockCopy(arrMsg, 0, arrMsgSend, 1, arrMsg.Length);

socketClient.Send(arrMsgSend);
MsgShow("已经将"+msg+"发送到服务端");
}

private void btnChoiceFile_Click(object sender, EventArgs e)
{
OpenFileDialog ofd = new OpenFileDialog();
if (ofd.ShowDialog() == System.Windows.Forms.DialogResult.OK)
{
txtFilePath.Text = ofd.FileName;
}

}

private void btnSendFile_Click(object sender, EventArgs e)
{
using(FileStream fs=new FileStream(txtFilePath.Text,FileMode.Open))
{
byte[] arrFile = new byte[1024 * 1024 * 2];
int length = fs.Read(arrFile, 0, arrFile.Length);
byte[] arrFileSend = new byte[length + 1];
arrFileSend[0] = 1;
Buffer.BlockCopy(arrFile, 0,  arrFileSend,1, length );
socketClient.Send(arrFileSend);
MsgShow("传送成功！");
}
}

}
}