本文灵感来自Andre Azevedo 在CodeProject上面的一片文章，An Asynchronous Socket Server and Client，讲的是异步的Socket通信。
关于技术博客，我觉得永远是老外的比较好~Andre Azevedo的这篇文章里，给出了一个很复杂的例子，内容涉及如下
- Socket连接(Socket Connection)
- Socket服务(Socket Service)
- 连接主机(Connection Host)
- 加密与压缩(Encrypt与Compress)
- 请求入队(Enqueuing Requests)
- 确保发送和接收(Ensure send and recieve)
- 检查消息头(Check message header)
- 检查空闲连接(Checking idle connections)
- 加密服务
- SSL认证(SSL authentication)
- 对称认证(Symmetric authentication)
- 连接创建者(Connection Creator)
- Socket服务器与Socket侦听者(SocketServer and SocketListener)
- Socket服务器构造函数与方法(SocketServer constructor and methods)
- Socket客户端与Socket连接者(SocketClient and SocketConnector)
- Socket客户端构造函数与方法(SocketClient constructor and methods)
- 应答演示项目(Echo Demo Project)
- 主机(Hosts)
- 服务(Services)
- 结语(Conclusion)
- 版本历史(History)
本文仅实现一个相对简单的异步Socket服务器与客户端通信示例。
首先需要说明如下2个问题
1.同步、异步、多线程是什么关系？答：同步是等待返回，相当于阻塞式；异步是不等待返回，是非阻塞式，可以用多线程实现。
2.有些异步方法有两种实现方式, 如BeginAccept()和AcceptAsync(), 这两个方法有什么区别呢?答： 以 Begin 和 End 开头的方法是以 APM(Asynchronous Programming Model)设计方法实现的异步操作, 以 Async 结尾的方法是利用称为 EAP (Event-based Asynchronous Pattern) 的设计方法实现的异步操作。
界面简单如下：
主要代码如下：
using System;
using System.Net;
using System.Net.Sockets;
using System.Text;
namespace Chatting
{
public abstract class SocketFunc
{
//不管是服务端还是客户端, 建立连接后用这个Socket进行通信
public Socket communicateSocket = null;
//服务端和客户端建立连接的方式稍有不同, 子类会重载
public abstract void Access(string IP, System.Action AccessAciton);
//发送消息的函数
public void Send(string message)
{
if (communicateSocket.Connected == false)
{
throw new Exception("还没有建立连接, 不能发送消息");
}
Byte[] msg = Encoding.UTF8.GetBytes(message);
communicateSocket.BeginSend(msg,0, msg.Length, SocketFlags.None,
ar => {
}, null);
}
//接受消息的函数
public void Receive(System.Action<string> ReceiveAction)
{
//如果消息超过1024个字节, 收到的消息会分为(总字节长度/1024 +1)条显示
Byte[] msg = new byte[1024];
//异步的接受消息
communicateSocket.BeginReceive(msg, 0, msg.Length, SocketFlags.None,
ar => {
//对方断开连接时, 这里抛出Socket Exception
//An existing connection was forcibly closed by the remote host
communicateSocket.EndReceive(ar);
ReceiveAction(Encoding.UTF8.GetString(msg).Trim('\0',' '));
Receive(ReceiveAction);
}, null);
}
}
public class ServerSocket:SocketFunc
{
//服务端重载Access函数
public override void Access(string IP, System.Action AccessAciton)
{
Socket serverSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
//本机预使用的IP和端口
IPEndPoint serverIP = new IPEndPoint(IPAddress.Any, 9050);
//绑定服务端设置的IP
serverSocket.Bind(serverIP);
//设置监听个数
serverSocket.Listen(1);
//异步接收连接请求
serverSocket.BeginAccept(ar =>
{
base.communicateSocket = serverSocket.EndAccept(ar);
AccessAciton();
}, null);
}
}
public class ClientSocket:SocketFunc
{
//客户端重载Access函数
public override void Access(string IP, System.Action AccessAciton)
{
base.communicateSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
base.communicateSocket.Bind(new IPEndPoint(IPAddress.Any, 9051));
//服务器的IP和端口
IPEndPoint serverIP;
try
{
serverIP = new IPEndPoint(IPAddress.Parse(IP), 9050);
}
catch
{
throw new Exception(String.Format("{0}不是一个有效的IP地址!", IP));
}
//客户端只用来向指定的服务器发送信息,不需要绑定本机的IP和端口,不需要监听
try
{
base.communicateSocket.BeginConnect(serverIP, ar =>
{
AccessAciton();
}, null);
}
catch
{
throw new Exception(string.Format("尝试连接{0}不成功!", IP));
}
}
}
}
相关的事件处理程序，如下：
View Code
using System; using System.Drawing; using System.Windows.Forms; using System.Net.Sockets; namespace Chatting { public partial class MainForm : Form { public MainForm() { InitializeComponent(); } SocketFunc socket; System.Action<string> ReceiveAction; System.Action AccessAction; private void MainForm_Load(object sender, EventArgs e) { //异步建立连接回调 AccessAction = () => { this.Invoke((MethodInvoker)delegate() { lblFriendIP.Visible = false; txtIP.Visible = false; btnConnect.Visible = false; btnWaitAccess.Visible = false; String friendIP = socket.communicateSocket.RemoteEndPoint.ToString(); lblState.Text = String.Format("连接成功. 对方IP:{0}", friendIP); try { socket.Receive(ReceiveAction); } catch (Exception exp) { MessageBox.Show(exp.Message, "错误"); } }); }; //异步接收消息回调 ReceiveAction = msg => { txtGetMsg.Invoke((MethodInvoker)delegate() { UpdateGetMsgTextBox(false, msg, Color.Red); }); }; } private void btnWaitAccess_Click(object sender, EventArgs e) { this.socket = new ServerSocket(); try { this.socket.Access("", this.AccessAction); } catch (Exception ecp) { MessageBox.Show(ecp.Message, "错误"); } lblState.Text = "等待对方连接..."; } private void btnConnect_Click(object sender, EventArgs e) { this.socket = new ClientSocket(); try { this.socket.Access(txtIP.Text, this.AccessAction); } catch (Exception ecp) { MessageBox.Show(ecp.Message, "错误"); } lblState.Text = "正在连接对方..."; } private void btnSendMsg_Click(object sender, EventArgs e) { string message = txtSendMsg.Text.Trim(); if (string.IsNullOrEmpty(message)) { MessageBox.Show("消息内容不能为空!", "错误"); txtSendMsg.Focus(); return; } try { socket.Send(message); } catch(Exception ecp) { MessageBox.Show(ecp.Message, "错误"); return; } UpdateGetMsgTextBox(true, message, Color.Blue); txtSendMsg.Text = ""; } private void UpdateGetMsgTextBox(bool sendMsg, string message, Color color) { string appendText; if (sendMsg == true) { appendText = "Client: " + System.DateTime.Now.ToString() + Environment.NewLine + message + Environment.NewLine; } else { appendText = "Server: " + System.DateTime.Now.ToString() + Environment.NewLine + message + Environment.NewLine; } int txtGetMsgLength = txtGetMsg.Text.Length; txtGetMsg.AppendText(appendText); txtGetMsg.Select(txtGetMsgLength, appendText.Length - Environment.NewLine.Length*2 -message.Length); txtGetMsg.SelectionColor = color; txtGetMsg.ScrollToCaret(); } private void txtSendMsg_Click(object sender, EventArgs e) { SetStyle(ControlStyles.SupportsTransparentBackColor, true); BackColor = Color.FromArgb(50, 40, 60, 82); } } }
效果，如下：
