使用SocketAsyncEventArgs之前需要先建立一个Socket监听对象，使用如下代码：
public void Start(IPEndPoint localEndPoint)
{
listenSocket = new Socket(localEndPoint.AddressFamily, SocketType.Stream, ProtocolType.Tcp);
listenSocket.Bind(localEndPoint);
listenSocket.Listen(m_numConnections);
Program.Logger.InfoFormat("Start listen socket {0} success", localEndPoint.ToString());
//for (int i = 0; i < 64; i++) //不能循环投递多次AcceptAsync，会造成只接收8000连接后不接收连接了
StartAccept(null);
m_daemonThread = new DaemonThread(this);
}然后开始接受连接，SocketAsyncEventArgs有连接时会通过Completed事件通知外面，所以接受连接的代码如下：
public void StartAccept(SocketAsyncEventArgs acceptEventArgs)
{
if (acceptEventArgs == null)
{
acceptEventArgs = new SocketAsyncEventArgs();
acceptEventArgs.Completed += new EventHandler<SocketAsyncEventArgs>(AcceptEventArg_Completed);
}
else
{
acceptEventArgs.AcceptSocket = null; //释放上次绑定的Socket，等待下一个Socket连接
}
m_maxNumberAcceptedClients.WaitOne(); //获取信号量
bool willRaiseEvent = listenSocket.AcceptAsync(acceptEventArgs);
if (!willRaiseEvent)
{
ProcessAccept(acceptEventArgs);
}
}接受连接响应事件代码：
void AcceptEventArg_Completed(object sender, SocketAsyncEventArgs acceptEventArgs)
{
try
{
ProcessAccept(acceptEventArgs);
}
catch (Exception E)
{
Program.Logger.ErrorFormat("Accept client {0} error, message: {1}", acceptEventArgs.AcceptSocket, E.Message);
Program.Logger.Error(E.StackTrace);
}
}
private void ProcessAccept(SocketAsyncEventArgs acceptEventArgs)
{
Program.Logger.InfoFormat("Client connection accepted. Local Address: {0}, Remote Address: {1}",
acceptEventArgs.AcceptSocket.LocalEndPoint, acceptEventArgs.AcceptSocket.RemoteEndPoint);
AsyncSocketUserToken userToken = m_asyncSocketUserTokenPool.Pop();
m_asyncSocketUserTokenList.Add(userToken); //添加到正在连接列表
userToken.ConnectSocket = acceptEventArgs.AcceptSocket;
userToken.ConnectDateTime = DateTime.Now;
try
{
bool willRaiseEvent = userToken.ConnectSocket.ReceiveAsync(userToken.ReceiveEventArgs); //投递接收请求
if (!willRaiseEvent)
{
lock (userToken)
{
ProcessReceive(userToken.ReceiveEventArgs);
}
}
}
catch (Exception E)
{
Program.Logger.ErrorFormat("Accept client {0} error, message: {1}", userToken.ConnectSocket, E.Message);
Program.Logger.Error(E.StackTrace);
}
StartAccept(acceptEventArgs); //把当前异步事件释放，等待下次连接
}接受连接后，从当前Socket缓冲池AsyncSocketUserTokenPool中获取一个用户对象AsyncSocketUserToken，AsyncSocketUserToken包含一个接收异步事件m_receiveEventArgs，一个发送异步事件m_sendEventArgs，接收数据缓冲区m_receiveBuffer，发送数据缓冲区m_sendBuffer，协议逻辑调用对象m_asyncSocketInvokeElement，建立服务对象后，需要实现接收和发送的事件响应函数：
void IO_Completed(object sender, SocketAsyncEventArgs asyncEventArgs)
{
AsyncSocketUserToken userToken = asyncEventArgs.UserToken as AsyncSocketUserToken;
userToken.ActiveDateTime = DateTime.Now;
try
{
lock (userToken)
{
if (asyncEventArgs.LastOperation == SocketAsyncOperation.Receive)
ProcessReceive(asyncEventArgs);
else if (asyncEventArgs.LastOperation == SocketAsyncOperation.Send)
ProcessSend(asyncEventArgs);
else
throw new ArgumentException("The last operation completed on the socket was not a receive or send");
}
}
catch (Exception E)
{
Program.Logger.ErrorFormat("IO_Completed {0} error, message: {1}", userToken.ConnectSocket, E.Message);
Program.Logger.Error(E.StackTrace);
}
}在Completed事件中需要处理发送和接收的具体逻辑代码，其中接收的逻辑实现如下：
private void ProcessReceive(SocketAsyncEventArgs receiveEventArgs)
{
AsyncSocketUserToken userToken = receiveEventArgs.UserToken as AsyncSocketUserToken;
if (userToken.ConnectSocket == null)
return;
userToken.ActiveDateTime = DateTime.Now;
if (userToken.ReceiveEventArgs.BytesTransferred > 0 && userToken.ReceiveEventArgs.SocketError == SocketError.Success)
{
int offset = userToken.ReceiveEventArgs.Offset;
int count = userToken.ReceiveEventArgs.BytesTransferred;
if ((userToken.AsyncSocketInvokeElement == null) & (userToken.ConnectSocket != null)) //存在Socket对象，并且没有绑定协议对象，则进行协议对象绑定
{
BuildingSocketInvokeElement(userToken);
offset = offset + 1;
count = count - 1;
}
if (userToken.AsyncSocketInvokeElement == null) //如果没有解析对象，提示非法连接并关闭连接
{
Program.Logger.WarnFormat("Illegal client connection. Local Address: {0}, Remote Address: {1}", userToken.ConnectSocket.LocalEndPoint,
userToken.ConnectSocket.RemoteEndPoint);
CloseClientSocket(userToken);
}
else
{
if (count > 0) //处理接收数据
{
if (!userToken.AsyncSocketInvokeElement.ProcessReceive(userToken.ReceiveEventArgs.Buffer, offset, count))
{ //如果处理数据返回失败，则断开连接
CloseClientSocket(userToken);
}
else //否则投递下次介绍数据请求
{
bool willRaiseEvent = userToken.ConnectSocket.ReceiveAsync(userToken.ReceiveEventArgs); //投递接收请求
if (!willRaiseEvent)
ProcessReceive(userToken.ReceiveEventArgs);
}
}
else
{
bool willRaiseEvent = userToken.ConnectSocket.ReceiveAsync(userToken.ReceiveEventArgs); //投递接收请求
if (!willRaiseEvent)
ProcessReceive(userToken.ReceiveEventArgs);
}
}
}
else
{
CloseClientSocket(userToken);
}
}由于我们制定的协议第一个字节是协议标识，因此在接收到第一个字节的时候需要绑定协议解析对象，具体代码实现如下：
private void BuildingSocketInvokeElement(AsyncSocketUserToken userToken)
{
byte flag = userToken.ReceiveEventArgs.Buffer[userToken.ReceiveEventArgs.Offset];
if (flag == (byte)SocketFlag.Upload)
userToken.AsyncSocketInvokeElement = new UploadSocketProtocol(this, userToken);
else if (flag == (byte)SocketFlag.Download)
userToken.AsyncSocketInvokeElement = new DownloadSocketProtocol(this, userToken);
else if (flag == (byte)SocketFlag.RemoteStream)
userToken.AsyncSocketInvokeElement = new RemoteStreamSocketProtocol(this, userToken);
else if (flag == (byte)SocketFlag.Throughput)
userToken.AsyncSocketInvokeElement = new ThroughputSocketProtocol(this, userToken);
else if (flag == (byte)SocketFlag.Control)
userToken.AsyncSocketInvokeElement = new ControlSocketProtocol(this, userToken);
else if (flag == (byte)SocketFlag.LogOutput)
userToken.AsyncSocketInvokeElement = new LogOutputSocketProtocol(this, userToken);
if (userToken.AsyncSocketInvokeElement != null)
{
Program.Logger.InfoFormat("Building socket invoke element {0}.Local Address: {1}, Remote Address: {2}",
userToken.AsyncSocketInvokeElement, userToken.ConnectSocket.LocalEndPoint, userToken.ConnectSocket.RemoteEndPoint);
}
}发送响应函数实现需要注意，我们是把发送数据放到一个列表中，当上一个发送事件完成响应Completed事件，这时我们需要检测发送队列中是否存在未发送的数据，如果存在则继续发送。
private bool ProcessSend(SocketAsyncEventArgs sendEventArgs)
{
AsyncSocketUserToken userToken = sendEventArgs.UserToken as AsyncSocketUserToken;
if (userToken.AsyncSocketInvokeElement == null)
return false;
userToken.ActiveDateTime = DateTime.Now;
if (sendEventArgs.SocketError == SocketError.Success)
return userToken.AsyncSocketInvokeElement.SendCompleted(); //调用子类回调函数
else
{
CloseClientSocket(userToken);
return false;
}
}SendCompleted用于回调下次需要发送的数据，具体实现过程如下：
public virtual bool SendCompleted()
{
m_activeDT = DateTime.UtcNow;
m_sendAsync = false;
AsyncSendBufferManager asyncSendBufferManager = m_asyncSocketUserToken.SendBuffer;
asyncSendBufferManager.ClearFirstPacket(); //清除已发送的包
int offset = 0;
int count = 0;
if (asyncSendBufferManager.GetFirstPacket(ref offset, ref count))
{
m_sendAsync = true;
return m_asyncSocketServer.SendAsyncEvent(m_asyncSocketUserToken.ConnectSocket, m_asyncSocketUserToken.SendEventArgs,
asyncSendBufferManager.DynamicBufferManager.Buffer, offset, count);
}
else
return SendCallback();
}
//发送回调函数，用于连续下发数据
public virtual bool SendCallback()
{
return true;
}当一个SocketAsyncEventArgs断开后，我们需要断开对应的Socket连接，并释放对应资源，具体实现函数如下：
