在开发异步Udp程序的过程中，通常在关闭UDP的时候回遇到诸如socket 访问已释放的资源之类的异常，如下简单操作下：
1 Udp的监听
2 this.serverSocket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
3 this.serverSocket.SetSocketOption(SocketOptionLevel.Socket,SocketOptionName.ReuseAddress,true);
4 this.serverSocket.Bind(new IPEndPoint(IPAddress.Parse("192.168.1.12"), port));
5 EndPoint remoteEP = new IPEndPoint(IPAddress.Any, 0);
6 this.serverSocket.BeginReceiveFrom(this.buff, 0, this.buff.Length, SocketFlags.None, ref remoteEP, new AsyncCallback(this.Receive), remoteEP);
Udp的关闭
if (this.serverSocket != null)
{
this.serverSocket.Close();
this.serverSocket = null;
}
当在进行关闭的时候，可能就出现错误，这个应该是多线程资源同步到问题，主线程进行了关闭，然而Udp线程也同样在访问socket，socket都释放了，而Udp线程却还在进行，因此产生异常；
解决的方法很简单，在Udp中访问serverSokcet加一个线程锁，再关闭的时候就应该不会产生异常了！
如下：
private void Receive(IAsyncResult ar)
{
IPEndPoint point = new IPEndPoint(IPAddress.Any, 0);
EndPoint endPoint = point;
try
{
lock (locker)
{
if (serverSocket != null)
{
int num = this.serverSocket.EndReceiveFrom(ar, ref endPoint);
List<byte> recBytes = new List<byte>();
for (int i = 0; i < num; i++)
{
recBytes.Add(this.buff[i]);
}
this.OnDataReceived(new DataReceivedEventArgs(endPoint, recBytes));
}
}
}
catch
{
}
finally
{
lock (locker)
{
if(serverSocket!=null)
this.serverSocket.BeginReceiveFrom(this.buff, 0, this.buff.Length, SocketFlags.None, ref endPoint, new AsyncCallback(this.Receive), endPoint);
}
} }
public void Close()
{
lock (locker)
{
if (this.serverSocket != null)
{
this.serverSocket.Close();
this.serverSocket = null;
}
}
}
