在.NET Compact Framework 1.x下进行UDP通信的步骤

上篇中，我介绍了如何进行本地Socket通信，那只是粗略的介绍了一下Smartphone和PC端IP的获龋我个人认为Smartphone/PC这种虚拟网卡连接结构，实现本地的通讯，UDP是个不错的选择。UDP是面向无连接的，对于SmartPhone来说所占的资源开销会少得多，而且要比TCP稳定的多。当然这需要我们自己在通讯协议上进行控制，不过SmartPhone/PC这种结构，网络环境相对比较简单，也无须做过多控制。

在SmartPhone/PC结构中，我觉得比较适合与胖客户端和胖服务端，姑且不论我的提法是否正确，我想要说的是，我们在做SmartPhone/PC的网络通讯的时候，可以采取相对简单的协议，真正的业务处理要交由SmartPhone或者PC。

这里，我只给出一个经过我修改UDP Server，UDP中其实无所谓Server与Client，Server也可以作为Client来看待，当然UDP Server用来做UDP Client也是非常合理。

UDPCommon.cs

using System;
using System.Collections.Generic;
using System.Text;
using System.Net;
using System.Net.Sockets;
using System.Threading;
using System.Text;

namespace UDPCS
{
class UDPCommon
{
public delegate void ReceivedHandler(object o, ReceivedEventArgs e);
public delegate void ReceivedBufferHandler(object o, ReceivedBufferEventArgs e);

private Thread m_UDPThread; //UDP接收线程
private string m_CurrentIP; //本地IP
private int m_CurrentPort; //本地端口
private IPEndPoint m_LocalEndPoint; //本地IP和端口容器
private Socket m_Socket; //UDP Socket

private int m_iState;

public UDPCommon()
{

}

public event ReceivedHandler OnReceivedData;
public event ReceivedBufferHandler OnReceivedBuffer;

public int StartListen(string IP, int Port)
{
m_CurrentIP = IP;
m_CurrentPort = Port;

//尝试启动接收线程
try
{
m_UDPThread = new Thread(new ThreadStart(ReceiveLoop));
m_UDPThread.Name = "RecieveThread";
m_UDPThread.Start();
}
catch (Exception e)
{
return UDPConstants.UDP_LISTEN_FAIL;
}
return UDPConstants.UDP_LISTEN_SUCESS;
}

public int StopListen()
{
if (m_iState != UDPConstants.UPD_STATE_LISTENING)
{
return UDPConstants.UDP_LISTEN_FAIL;
}

m_iState = UDPConstants.UDP_STATE_CLOSING;

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

m_UDPThread.Abort();
m_UDPThread = null;

return UDPConstants.UDP_OK;
}

private void ReceiveLoop()
{
if (m_CurrentIP == "")
m_LocalEndPoint = new IPEndPoint(IPAddress.Any, m_CurrentPort);
else
m_LocalEndPoint = new IPEndPoint(IPAddress.Parse(m_CurrentIP), m_CurrentPort);

try
{
m_Socket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
m_Socket.Bind(m_LocalEndPoint);

m_iState = UDPConstants.UPD_STATE_LISTENING;

while (true)
{
try
{
//Make space to store the data from the socket
Byte[] received = new Byte[UDPConstants.MAX_BUFFER_LEN];

//Create an end point, just give it temporary values
EndPoint remoteEP = new IPEndPoint(m_LocalEndPoint.Address, m_LocalEndPoint.Port);

//Read bytes from the socket
int bytesReceived = m_Socket.ReceiveFrom(received, ref remoteEP);
string str_received = UnicodeEncoding.ASCII.GetString(received, 0, bytesReceived);
IPEndPoint remoteIPEP = (IPEndPoint)remoteEP;
if(OnReceivedData != null)
{
OnReceivedData(null, new ReceivedEventArgs((IPEndPoint)remoteEP, str_received));
}
if (OnReceivedBuffer != null)
{
OnReceivedBuffer(null, new ReceivedBufferEventArgs((IPEndPoint)remoteEP, received, bytesReceived));
}
}
catch
{

}
}
}
catch
{

}
}

public int SendBuffer(string IP, int Port, byte[] buffer)
{
if (m_iState != UDPConstants.UPD_STATE_LISTENING)
return UDPConstants.UDP_SEND_FAIL;

try
{

EndPoint remoteEP = new IPEndPoint(IPAddress.Parse(IP), Port);
m_Socket.SendTo(buffer, remoteEP);
}
catch (SocketException se)
{
return UDPConstants.UDP_SEND_FAIL;
}
catch (Exception e)
{
return UDPConstants.UDP_SEND_FAIL;
}
return UDPConstants.UDP_SEND_SUCESS;
}

public int SendData(string IP, int Port, string Data)
{
if (m_iState != UDPConstants.UPD_STATE_LISTENING)
return UDPConstants.UDP_SEND_FAIL;

try
{
//byte[] databytes = Encoding.UTF8.GetBytes(Data);
byte[] databytes = UnicodeEncoding.ASCII.GetBytes(Data);

EndPoint remoteEP = new IPEndPoint(IPAddress.Parse(IP), Port);
m_Socket.SendTo(databytes, remoteEP);
}
catch (SocketException se)
{
return UDPConstants.UDP_SEND_FAIL;
}
catch (Exception e)
{
return UDPConstants.UDP_SEND_FAIL;
}
return UDPConstants.UDP_SEND_SUCESS;
}

public class ReceivedEventArgs : EventArgs
{
public readonly IPEndPoint RemoteHost;
public readonly string Data;

public ReceivedEventArgs(IPEndPoint Remote, string ReceivedData)
{
Data = ReceivedData;
RemoteHost = Remote;
}
}

public class ReceivedBufferEventArgs : EventArgs
{
public readonly IPEndPoint RemoteHost;
public readonly byte[] Data;
public readonly int Size;

public ReceivedBufferEventArgs(IPEndPoint Remote, byte[] ReceivedData, int DataSize)
{
Data = ReceivedData;
RemoteHost = Remote;
Size = DataSize;
}
}
}
}

UDPConstants.cs

using System;
using System.Collections.Generic;
using System.Text;

namespace UDPCS
{
class UDPConstants
{
public static int UDP_LISTEN_SUCESS = 1;
public static int UDP_LISTEN_FAIL = -1;
public static int UPD_STATE_LISTENING = 2;
public static int UDP_STATE_CLOSING = 3;
public static int UDP_OK = 4;
public static int UDP_SEND_FAIL = 5;
public static int UDP_SEND_SUCESS = 6;

//我设置的缓冲比较大，但是8K的开销还是可以负担的

public static int MAX_BUFFER_LEN = 1024 * 8;
}
}

Good Luck！

注：部分代码出自CodeProject的Demo！