C# 網路程式：TCP 程式設計
TCP 簡介
TCP 是一個連線導向的網路傳輸協定，程式通常在斷線之前會一直記住這個連線。在我們使用 Socket 函式庫設計 TCP 網路程式時，通常會讓一個 Thread 負責處理一條連線，這樣可以讓問題變得較為單純，因為不需要用表格去記住連線。
所以，在學習 TCP 程式設計之前，我們有必要先複習一下 Thread (台灣稱為執行緒、中國大陸稱為線程) 的程式設計方式，若讀者對 Thread 尚不熟悉，請先閱讀本書的 Thread 章節。
TCP 的程式架構
TCP 客戶端的通常在連上伺服端後，就會用一個迴圈透過 Socket.send 函數傳送訊息，以下是一個典型的 TCP 客戶端程式。
客戶端：Client
IPEndPoint ip = new IPEndPoint(IPAddress.Parse(address), port);
Socket server = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
server.Connect(ip);
...
while(true) {
...
server.Send(data);
...
}
...
server.Shutdown(SocketShutdown.Both);
server.Close();
TCP 伺服端通常較為複雜，首先在利用 Socket 中的 bind() 函數佔用特定的 port 之後，會再進入一個無窮迴圈，在迴圈中利用 socket.Accept() 接受客戶端的連線，此時會產生一個新的 Socket 物件。通常，我們會建立一個新的 Thread 去處理這個連線，因此在下列程式中，我們建立了 TcpListener 這個物件，以便讓一個 Listener 處理一個 Socket 連線。
伺服端：Server
public class TcpServer
{
public static void Main()
{
IPEndPoint ip = new IPEndPoint(IPAddress.Any, port);
Socket socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
socket.Bind(ip);
socket.Listen(10);
while(true)
{
Socket client = socket.Accept();
TcpListener listener = new TcpListener(client); // 建立 Listener 物件處理這個連線。
Thread thread = new Thread(new ThreadStart(listener.run)); // 建立 listener.run 的 Thread。
thread.Start(); // 啟動 Thread
...
}
...
}
}
public class TcpListener {
Socket socket;
public TcpListener(Socket s) { socket = s; }
public void run() { // Thread 的主要函數
while (true) {
...
byte[] data = new byte[1024];
int recv = socket.Receive(data); // 接收資料
...
}
socket.Close();
}
}
以上就是一個典型的 TCP 程式架構，該架構包含了『客戶端-伺服端』兩個部分，客戶端透過 Socket.send 傳送訊息，而伺服端則會針對每一個連線，建立新的 Thread ，以便處理連線的互動關係。這種架構對 TCP 而言是較為簡單的，有幾個連線就建立幾個 Thread。由於這種架構不需要用表格記住連線，因此簡化了伺服端的管理，讓程式設計更為容易。
在理解了這個架構後，讓我們來看看幾個真實的程式範例：
TCP 單向的訊息傳遞程式
由於網路程式必須有連線，因此至少要有兩個程式才能運作，通常主動連線的一方稱為 Client，被動等待連線的一方稱為 Server，這就是所謂的 Client - Server 架構。
在本範例中，我們撰寫了一個 TcpClient 與一個 TcpServer 程式，TcpClient 連線到 TcpServer 之後，會將使用者所輸入的文字傳司送給 TcpServer。當 TcpServer 收到這些文字之後會印出在螢幕上，這個範例示範了一個極為簡單的網路程式架構。
檔案：TcpClient1.cs
using System;
using System.Net;
using System.Net.Sockets;
using System.Text;
public class TcpClient
{
public static void Main(string[] args)
{
IPEndPoint ipep = new IPEndPoint(IPAddress.Parse(args[0]), 20);
Socket server = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
server.Connect(ipep);
while(true)
{
string input = Console.ReadLine();
if (input == "exit")
break;
byte[] data = Encoding.UTF8.GetBytes(input);
// byte[] data = Encoding.ASCII.GetBytes(input);
server.Send(data);
}
Console.WriteLine("Disconnecting from server...");
server.Shutdown(SocketShutdown.Both);
server.Close();
}
}
檔案：TcpServer1.cs
using System;
using System.Net;
using System.Net.Sockets;
using System.Text;
using System.Threading;
public class TcpServer
{
public static void Main()
{
IPEndPoint ipep = new IPEndPoint(IPAddress.Any, 20);
Socket newsock = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
newsock.Bind(ipep);
newsock.Listen(10);
while(true)
{
Socket client = newsock.Accept();
IPEndPoint clientep = (IPEndPoint) client.RemoteEndPoint;
Console.WriteLine("Client End Point = " + clientep);
// create a new thread and then receive message.
TcpListener listener = new TcpListener(client);
Thread thread = new Thread(new ThreadStart(listener.run));
thread.Start();
}
// newsock.Close();
}
}
public class TcpListener {
Socket socket;
public TcpListener(Socket s)
{
socket = s;
}
public void run()
{
try {
while (true)
{
byte[] data = new byte[1024];
int recv = socket.Receive(data);
if (recv == 0) break;
Console.WriteLine(Encoding.UTF8.GetString(data, 0, recv));
}
socket.Close();
} catch (Exception e) {
Console.WriteLine("Client "+socket.RemoteEndPoint+" Error : close");
Console.WriteLine(e);
}
}
}
TCP 雙向聊天程式
聊天程式是學習網路程式設計很好的入門題目之一，在本文中，我們將示範如何用 C# 的 Socket 函式庫設計一個網路聊天程式。以下是這個程式的執行時的一個畫面，讀者可以看到我們在兩個命令列視窗中執行同一個 ChatBox 程式，左上角是 Server 程式，右下角是 Client 程式。
在上圖中，Client 可以傳送訊息給 Server ，而 Server 也可傳送訊息給 Client，由於雙方在這個傳送接收的動作上幾乎是相同的，因此在寫程式時就將這些動作封裝後共用，可以讓程式更為精簡，這就是 P2P 架構的程式。
當然，這個程式也可以放在兩台不同的電腦上執行，其結果將與上述結果類似，只是無法同時在一台電腦上看到輸入與輸出的結果而已。
以下是上述雙向聊天程式 ChatBox 的原始程式碼，其中的 TcpListener 程式是 Client-Server 雙方所共用的部分，因此獨立出來變成一個類別，並且分別在 Client 與 Server 主程式當中都用 new TcpListener() 的方式呼叫。此時雙方都會建立一個寫入迴圈 (outLoop) 與讀取回圈 (inLoop)，寫入迴圈不斷等待鍵盤的輸入，並在有輸入時將訊息傳遞給對方。而讀取回圈則是不斷接收對方所傳來的訊息並顯示在螢幕上。
using System;
using System.Collections.Generic;
using System.Text;
using System.Net;
using System.Net.Sockets;
using System.IO;
using System.Threading;
class ChatBox
{
int port = 20;
public static void Main(String[] args)
{
ChatBox chatBox = new ChatBox();
if (args.Length == 0)
chatBox.ServerMain();
else
chatBox.ClientMain(args[0]);
}
public void ServerMain()
{
IPEndPoint ipep = new IPEndPoint(IPAddress.Any, port);
Socket newsock = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
newsock.Bind(ipep);
newsock.Listen(10);
Socket client = newsock.Accept();
new TcpListener(client); // create a new thread and then receive message.
newsock.Close();
}
public void ClientMain(String ip)
{
IPEndPoint ipep = new IPEndPoint(IPAddress.Parse(ip), port);
Socket server = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
server.Connect(ipep);
new TcpListener(server);
server.Shutdown(SocketShutdown.Both);
server.Close();
}
}
public class TcpListener
{
Socket socket;
Thread inThread, outThread;
NetworkStream stream;
StreamReader reader;
StreamWriter writer;
public TcpListener(Socket s)
{
socket = s;
stream = new NetworkStream(s);
reader = new StreamReader(stream);
writer = new StreamWriter(stream);
inThread = new Thread(new ThreadStart(inLoop));
inThread.Start();
outThread = new Thread(new ThreadStart(outLoop));
outThread.Start();
inThread.Join(); // 等待 inThread 執行續完成，才離開此函數。
// (注意、按照 inLoop 的邏輯，這個函數永遠不會跳出，因為 inLoop 是個無窮迴圈)。
}
public void inLoop()
{
while (true)
{
String line = reader.ReadLine();
Console.WriteLine("收到：" + line);
}
}
public void outLoop()
{
while (true)
{
String line = Console.ReadLine();
writer.WriteLine(line);
writer.Flush();
}
}
}
TCP 多人聊天室 (視窗版)
專案程式下載：https://dl.dropbox.com/u/101584453/cs/code/ChattingRoom.zip
使用方法
// ---------------------------------------------------------------
// 共有四個程式檔案
//
// 程式檔 : ChatLib.cs
// 程式檔 : ChattingServer.cs
// 程式檔 : FormChatClient.cs
// 程式檔 : FormChatClient.Designer.cs
//
// 編譯方式 :
// 步驟 1 : csc ChatServer.cs ChatLib.cs
// 會產生 ChattingServer.exe 檔
//
// 步驟 2 : csc WinChatClient.cs FormChatClient.cs FormChatClilent.Designer.cs ChatLib.cs
// 會產生 WinChatClient.exe 檔
//
// 執行方式 :
// 步驟 1 : 執行 ChatServer.exe
// 步驟 2 : 執行 WinChatClient.exe (使用者 1)
// 步驟 3 : 執行 WinChatClient.exe (使用者 2)
//
// 如此，兩個 WinChatClient.exe 的視窗間即可透過本機聊天
// ---------------------------------------------------------------
檔案：ChatLib.cs
// ------------------------- ChatLib.cs --------------------------
using System;
using System.Net;
using System.Net.Sockets;
using System.IO;
using System.Threading;
namespace ChattingRoom
{
public class ChatSetting
{
public static String serverIp = "192.168.100.172";
public static int port = 3766;
}
public delegate String StrHandler(String str);
public class ChatSocket
{
public Socket socket;
public NetworkStream stream;
public StreamReader reader;
public StreamWriter writer;
public StrHandler inHandler;
public EndPoint remoteEndPoint;
public bool isDead = false;
public ChatSocket(Socket s)
{
socket = s;
stream = new NetworkStream(s);
reader = new StreamReader(stream);
writer = new StreamWriter(stream);
remoteEndPoint = socket.RemoteEndPoint;
}
public String receive()
{
return reader.ReadLine();
}
public ChatSocket send(String line)
{
writer.WriteLine(line);
writer.Flush();
return this;
}
public static ChatSocket connect(String ip)
{
IPEndPoint ipep = new IPEndPoint(IPAddress.Parse(ip), ChatSetting.port);
Socket socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
socket.Connect(ipep);
return new ChatSocket(socket);
}
public Thread newListener(StrHandler pHandler)
{
inHandler = pHandler;
Thread listenThread = new Thread(new ThreadStart(listen));
listenThread.Start();
return listenThread;
}
public void listen()
{
try
{
while (true)
{
String line = receive();
inHandler(line);
}
}
catch (Exception ex)
{
isDead = true;
Console.WriteLine(ex.Message);
}
}
}
}
檔案：ChattingServer.cs
// ------------------------- ChatServer.cs -------------------
using System;
using System.Net;
using System.Net.Sockets;
using System.IO;
using System.Threading;
using System.Collections.Generic;
namespace ChattingRoom
{
public class ChatServer
{
List<ChatSocket> clientList = new List<ChatSocket>();
public static void Main(String[] args)
{
ChatServer chatServer = new ChatServer();
chatServer.run();
}
public void run()
{
IPEndPoint ipep = new IPEndPoint(IPAddress.Any, ChatSetting.port);
Socket newsock = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
newsock.Bind(ipep);
newsock.Listen(10);
while (true)
{
Socket socket = newsock.Accept();
Console.WriteLine("接受一個新連線!");
ChatSocket client = new ChatSocket(socket);
try
{
clientList.Add(client);
client.newListener(processMsgComeIn);
}
catch
{
}
// clientList.Remove(client);
}
// newsock.Close();
}
public String processMsgComeIn(String msg)
{
Console.WriteLine("收到訊息："+msg);
broadCast(msg);
return "OK";
}
public void broadCast(String msg)
{
Console.WriteLine("廣播訊息給 " + msg+" 線上使用者共"+clientList.Count+"個人!");
foreach (ChatSocket client in clientList)
{
if (!client.isDead) {
Console.WriteLine("Send to "+client.remoteEndPoint.ToString()+":"+msg);
client.send(msg);
}
}
}
}
}
檔案：FormChatClient.cs
// ------------------------- FormChatClient.cs -------------------
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
namespace ChattingRoom
{
public partial class FormChatClient : Form
{
ChatSocket client;
StrHandler msgHandler;
public FormChatClient()
{
InitializeComponent();
msgHandler = this.addMsg;
}
private void buttonSend_Click(object sender, EventArgs e)
{
sendMsg();
}
private void textBoxMsg_KeyPress(object sender, KeyPressEventArgs e)
{
if (e.KeyChar == '\r')
sendMsg();
}
public String user() {
return textBoxUser.Text.Trim();
}
public String msg() {
return textBoxMsg.Text;
}
public void sendMsg()
{
if (user().Length == 0)
{
MessageBox.Show("請輸入使用者名稱!");
return;
}
if (client == null) {
client = ChatSocket.connect(ChatSetting.serverIp);
client.newListener(processMsgComeIn);
client.send(user() + " : 新使用者進入!");
textBoxUser.Enabled = false;
}
if (msg().Length > 0) {
client.send(user()+" : "+msg());
textBoxMsg.Text = "";
}
}
public String processMsgComeIn(String msg)
{
this.Invoke(msgHandler, new Object[] { msg });
return "OK";
}
public String addMsg(String msg)
{
richTextBoxBoard.AppendText(msg + "\n");
return "OK";
}
}
}
檔案：FormChatClient.Designer.cs
// ------------------------- FormChatClient.Designer.cs ----------
namespace ChattingRoom
{
partial class FormChatClient
{
/// <summary>
/// 設計工具所需的變數。
/// </summary>
private System.ComponentModel.IContainer components = null;
/// <summary>
/// 清除任何使用中的資源。
/// </summary>
/// <param name="disposing">如果應該公開 Managed 資源則為 true，否則為 false。</param>
protected override void Dispose(bool disposing)
{
if (disposing && (components != null))
{
components.Dispose();
}
base.Dispose(disposing);
}
#region Windows Form 設計工具產生的程式碼
/// <summary>
/// 此為設計工具支援所需的方法 - 請勿使用程式碼編輯器修改這個方法的內容。
///
/// </summary>
private void InitializeComponent()
{
this.panelInput = new System.Windows.Forms.Panel();
this.labelSaid = new System.Windows.Forms.Label();
this.textBoxUser = new System.Windows.Forms.TextBox();
this.textBoxMsg = new System.Windows.Forms.TextBox();
this.buttonSend = new System.Windows.Forms.Button();
this.panelPadding1 = new System.Windows.Forms.Panel();
this.panelMsg = new System.Windows.Forms.Panel();
this.richTextBoxBoard = new System.Windows.Forms.RichTextBox();
this.panelInput.SuspendLayout();
this.panelMsg.SuspendLayout();
this.SuspendLayout();
//
// panelInput
//
this.panelInput.Controls.Add(this.labelSaid);
this.panelInput.Controls.Add(this.textBoxUser);
this.panelInput.Controls.Add(this.textBoxMsg);
this.panelInput.Controls.Add(this.buttonSend);
this.panelInput.Controls.Add(this.panelPadding1);
this.panelInput.Dock = System.Windows.Forms.DockStyle.Bottom;
this.panelInput.Location = new System.Drawing.Point(0, 283);
this.panelInput.Name = "panelInput";
this.panelInput.Size = new System.Drawing.Size(494, 64);
this.panelInput.TabIndex = 0;
//
// labelSaid
//
this.labelSaid.AutoSize = true;
this.labelSaid.Font = new System.Drawing.Font("DFKai-SB", 15.75F, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, ((byte)(136)));
this.labelSaid.Location = new System.Drawing.Point(94, 17);
this.labelSaid.Name = "labelSaid";
this.labelSaid.Size = new System.Drawing.Size(54, 21);
this.labelSaid.TabIndex = 4;
this.labelSaid.Text = "說：";
//
// textBoxUser
//
this.textBoxUser.Location = new System.Drawing.Point(3, 17);
this.textBoxUser.Name = "textBoxUser";
this.textBoxUser.Size = new System.Drawing.Size(88, 22);
this.textBoxUser.TabIndex = 3;
//
// textBoxMsg
//
this.textBoxMsg.Location = new System.Drawing.Point(154, 17);
this.textBoxMsg.Name = "textBoxMsg";
this.textBoxMsg.Size = new System.Drawing.Size(250, 22);
this.textBoxMsg.TabIndex = 2;
this.textBoxMsg.KeyPress += new System.Windows.Forms.KeyPressEventHandler(this.textBoxMsg_KeyPress);
//
// buttonSend
//
this.buttonSend.Location = new System.Drawing.Point(410, 14);
this.buttonSend.Name = "buttonSend";
this.buttonSend.Size = new System.Drawing.Size(81, 28);
this.buttonSend.TabIndex = 1;
this.buttonSend.Text = "送出";
this.buttonSend.UseVisualStyleBackColor = true;
this.buttonSend.Click += new System.EventHandler(this.buttonSend_Click);
//
// panelPadding1
//
this.panelPadding1.Dock = System.Windows.Forms.DockStyle.Bottom;
this.panelPadding1.Location = new System.Drawing.Point(0, 48);
this.panelPadding1.Name = "panelPadding1";
this.panelPadding1.Size = new System.Drawing.Size(494, 16);
this.panelPadding1.TabIndex = 0;
//
// panelMsg
//
this.panelMsg.Controls.Add(this.richTextBoxBoard);
this.panelMsg.Dock = System.Windows.Forms.DockStyle.Fill;
this.panelMsg.Location = new System.Drawing.Point(0, 0);
this.panelMsg.Name = "panelMsg";
this.panelMsg.Size = new System.Drawing.Size(494, 283);
this.panelMsg.TabIndex = 1;
//
// richTextBoxBoard
//
this.richTextBoxBoard.Dock = System.Windows.Forms.DockStyle.Fill;
this.richTextBoxBoard.Location = new System.Drawing.Point(0, 0);
this.richTextBoxBoard.Name = "richTextBoxBoard";
this.richTextBoxBoard.Size = new System.Drawing.Size(494, 283);
this.richTextBoxBoard.TabIndex = 0;
this.richTextBoxBoard.Text = "";
//
// FormChatClient
//
this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 12F);
this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
this.ClientSize = new System.Drawing.Size(494, 347);
this.Controls.Add(this.panelMsg);
this.Controls.Add(this.panelInput);
this.Name = "FormChatClient";
this.Text = "C# 聊天室";
this.panelInput.ResumeLayout(false);
this.panelInput.PerformLayout();
this.panelMsg.ResumeLayout(false);
this.ResumeLayout(false);
}
#endregion
private System.Windows.Forms.Panel panelInput;
private System.Windows.Forms.Panel panelMsg;
private System.Windows.Forms.TextBox textBoxMsg;
private System.Windows.Forms.Button buttonSend;
private System.Windows.Forms.Panel panelPadding1;
private System.Windows.Forms.RichTextBox richTextBoxBoard;
private System.Windows.Forms.Label labelSaid;
private System.Windows.Forms.TextBox textBoxUser;
}
}
檔案：Program.cs (主程式)
using System;
using System.Collections.Generic;
using System.Windows.Forms;
namespace ChattingRoom
{
static class Program
{
/// <summary>
/// 應用程式的主要進入點。
/// </summary>
[STAThread]
static void Main()
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(new FormChatClient());
Application.Exit();
}
}
}