C#使用SocketAsyncEventArgs操作套接字的简单异步通讯

SocketAsyncEventArgs是一个套接字操作的类，主要作用是实现socket消息的异步接收和发送，跟Socket的BeginSend和
BeginReceive方法异步处理没有多大区别，它的优势在于完成端口的实现来处理大数据的并发情况，由于本人学习不久，对千万级的

数据访问还没有多大体会，这里的简单实现作为一个学习的笔记，请酌情参考，如有错误，请及时指正。

先说说SockeAsyncEventArgs类的操作方法，以下是摘自MSDN的内容（cn/library/system.net.sockets.socketasynceventargs.aspx">MSDN的SockeAsyncEventArgs类描述）：

1、分配一个新的 SocketAsyncEventArgs 上下文对象，或者从应用程序池中获取一个空闲的此类对象。

 　　SocketAsyncEventArgs saea = new SocketAsyncEventArgs();
 　　//或者(这里的SocketAsyncEventArgsPool类一般是自己实现，MSDN有通过栈结构实现的程序池，也可以使用队列或链表)：
 　　SocketAsyncEventArgs saea = new SocketAsyncEventArgsPool().Pop();

2、将该上下文对象的属性设置为要执行的操作（例如，完成回调方法、数据缓冲区、缓冲区偏移量以及要传输的最大数据量）。SocketAsyncEventArgs一般会根据操作执行相同的回调函数,所有设置内容在不同操作的回调都可以访问，我在调试时发现不能同时收发消息（可能是半双工），因此使用接收和发送试用两个对象

 　　byte[] buffer = new byte[];
 　　saea.SetBuffer(buffer, , buffer.Length);    //设置缓冲区
 　　saea.Completed += new EventHandler<SocketAsyncEventArgs>(MethodName);    //设置回调方法
 　　saea.RemoteEndPoint = new IPEndPoint(IPAddress.Any,);    //设置远端连接节点，一般用于接收消息
 　　saea.UserToken = new AsyncUserToken();     //设置用户信息，一般把连接的Socket对象放在这里

3、调用适当的套接字方法 (xxxAsync) 以启动异步操作。
4、如果异步套接字方法 (xxxAsync) 返回 true，则在回调中查询上下文属性来获取完成状态。
5、如果异步套接字方法 (xxxAsync) 返回 false，则说明操作是同步完成的。 可以查询上下文属性来获取操作结果。

 　　//这是调用套接字的方法，即socket调用的方法：
 　　Socket socket = saea.AcceptSocket;
 　　socket.ConnectAsync(saea);     //异步进行连接
 　　socket.AcceptAsync(saea);     //异步接收连接
 　　socket.ReceiveAsync(saea);     //异步接收消息
 　　socket.SendAsync(saea);     //异步发送消息
 　　//这里注意的是，每个操作方法返回的是布尔值，这个布尔值的作用，是表明当前操作是否有等待I/O的情况，如果返回false则表示当前是同步操作，不需要等待，此时要要同步执行回调方法，一般写法是
 　　bool willRaiseEvent = socket.ReceiveAsync(saea); //继续异步接收消息
 　　if (!willRaiseEvent)
 　　{
 　　　　MethodName(saea);
 　　}

6、将该上下文重用于另一个操作，将它放回到应用程序池中，或者将它丢弃。
　　如果用于持续监听连接，要注意saea.AcceptSocket = null;只有把saea对象的AcceptSocket置为null，才能监听到新的连接；
　　如果只用于单次通讯，则在用完saea对象是可丢弃，saea.Dispose(),如果想重复利用，则设置相应的异步操作即可，
　　

 saea.AcceptSocket = null;//重新监听
 socket.ReceiveAsync(saea);//重新接收
 socket.SendAsync(saea);//重新发送

关于具体的实现，类似于之前我记下的简单Socket通信，先是SocketServerManager的实现，该实现也是参考自MSDN：

     public class SocketServerManager
     {
         readonly Socket _socket;        //监听Socket
         readonly EndPoint _endPoint;
         private const int Backlog = ;     //允许连接数目
         private int byteSize = ;

         //同时UI界处理的事件
         public delegate void OnEventCompletedHanlder(MessageFormat msg);
         public event OnEventCompletedHanlder OnReceiveCompletedEvent;
         public event OnEventCompletedHanlder OnSendCompletedEvent;
         public event OnEventCompletedHanlder OnConnectedEvent;
         public event OnEventCompletedHanlder OnDisconnectEvent;
         public event OnEventCompletedHanlder OnNotConnectEvent;

         //private BufferManager bufferManager;        //消息缓存管理
         SocketAsyncEventArgsPool rwPool;              //SAEA池
         private Semaphore maxClient;
         private Dictionary<string, SocketAsyncEventArgs> dicSAEA = null; 

         public SocketServerManager(string ip, int port)
         {
             _socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
             IPAddress ipAddress = IPAddress.Parse(ip);
             _endPoint = new IPEndPoint(ipAddress, port);
             //bufferManager = new BufferManager(totalBytes, byteSize);
             maxClient = new Semaphore(Backlog, Backlog);
             Init();
         }

         public void Init()
         {
             //bufferManager.InitBuffer();
             SocketAsyncEventArgs rwEventArgs;
             rwPool = new SocketAsyncEventArgsPool(Backlog);
             dicSAEA = new Dictionary<string, SocketAsyncEventArgs>();
             for (int i = ; i < ; i++)
             {
                 rwEventArgs = new SocketAsyncEventArgs();
                 rwEventArgs.Completed += new EventHandler<SocketAsyncEventArgs>(IO_Completed);
                rwEventArgs.UserToken = new AsyncUserToken();

                 rwEventArgs.SetBuffer(new byte[byteSize],,byteSize);
                 //bufferManager.SetBuffer(rwEventArgs);

                 rwPool.Push(rwEventArgs);
             }
         }

         /// <summary>
         /// 开启Socket监听
         /// </summary>
         public void Start()
         {
             _socket.Bind(_endPoint);        //绑定本地地址进行监听
             _socket.Listen(Backlog);        //设置监听数量

             StartAccept(null);
         }

         public void StartAccept(SocketAsyncEventArgs acceptEventArg)
         {
             if (acceptEventArg == null)
             {
                 acceptEventArg = new SocketAsyncEventArgs();
                 acceptEventArg.Completed += new EventHandler<SocketAsyncEventArgs>(OnConnectedCompleted);
             }
             else
             {
                 acceptEventArg.AcceptSocket = null;
             }

             maxClient.WaitOne();
             bool willRaiseEvent = _socket.AcceptAsync(acceptEventArg);
             if (!willRaiseEvent)
             {
                 ProcessAccept(acceptEventArg);
             }
         }

         private void ProcessAccept(SocketAsyncEventArgs e)
         {
             if (e.SocketError != SocketError.Success) return;       //异步处理失败，不做处理
             SocketAsyncEventArgs saea = rwPool.Pop();
             AsyncUserToken token = saea.UserToken as AsyncUserToken;
             token.UserSocket = e.AcceptSocket;       //获取远端对话Socket对象
             string ipRemote = token.UserSocket.RemoteEndPoint.ToString();
             string ip = token.UserSocket.RemoteEndPoint.ToString();
             MessageFormat msg = new MessageFormat(string.Format("远程地址[{0}]成功连接到本地", ipRemote), ip, MsgType.Empty);
             msg.tag = MsgType.Empty;
             if (OnConnectedEvent != null) OnConnectedEvent(msg);            //调用UI方法处理

             //连接成功后，发送消息通知远程客户端
             //OnSend("Connected Success !", _sendSocket.RemoteEndPoint);
             SocketAsyncEventArgs sendArgs = new SocketAsyncEventArgs();
             sendArgs.RemoteEndPoint = token.UserSocket.RemoteEndPoint;
             sendArgs.Completed += new EventHandler<SocketAsyncEventArgs>(IO_Completed);
             sendArgs.UserToken = saea.UserToken;
             dicSAEA.Add(token.UserSocket.RemoteEndPoint.ToString(), sendArgs);
             bool willRaiseEvent = e.AcceptSocket.ReceiveAsync(saea);
             if (!willRaiseEvent)
             {
                 OnReceiveCompleted(saea);
             }

             StartAccept(e);
         }

         /// <summary>
         /// 远端地址连接本地成功的回调
         /// </summary>
         /// <param name="sender"></param>
         /// <param name="e"></param>
         public void OnConnectedCompleted(object sender, SocketAsyncEventArgs e)
         {
             ProcessAccept(e);
         }

         public void IO_Completed(object sender, SocketAsyncEventArgs e)
         {
             switch (e.LastOperation)
             {
                 case SocketAsyncOperation.Receive:
                     OnReceiveCompleted(e);
                     break;
                 case SocketAsyncOperation.Send:
                     OnSendCompleted(e);
                     break;
                 default:
                     throw new ArgumentException("The last operation completed on the socket was not a receive or send");
             }
         }

         /// <summary>
         /// 执行异步发送消息
         /// </summary>
         /// <param name="msg">消息内容</param>
         /// <param name="ip">发送远端地址</param>
         public void OnSend(MessageFormat mf)
         {
             if (!dicSAEA.ContainsKey(mf.ipStr))
             {
                 if (OnNotConnectEvent != null)
                 {
                     OnNotConnectEvent(new MessageFormat("不存在此连接客户端","",MsgType.Empty));
                     return;
                 }
             }
             SocketAsyncEventArgs saea = dicSAEA[mf.ipStr];
             AsyncUserToken token = saea.UserToken as AsyncUserToken;
             if (saea == null) return;
             //saea.SetBuffer(sendBuffer, 0, sendBuffer.Length);  //设置SAEA的buffer消息内容
             byte[] sendBuffer = Encoding.Unicode.GetBytes(string.Format("[length={0}]{1}", mf.msgStr.Length, mf.msgStr));
             saea.SetBuffer(sendBuffer, , sendBuffer.Length);
             bool willRaiseEvent = token.UserSocket.SendAsync(saea);
             if (!willRaiseEvent)
             {
                 OnSendCompleted(saea);
             }
         }

         /// <summary>
         /// 发送消息回调处理
         /// </summary>
         /// <param name="sender"></param>
         /// <param name="e"></param>
         public void OnSendCompleted(SocketAsyncEventArgs e)
         {
             AsyncUserToken token = e.UserToken as AsyncUserToken;
             byte[] sendBuffer = e.Buffer;
             string msgStr = Encoding.Unicode.GetString(sendBuffer);
             string ipAddress = token.UserSocket.RemoteEndPoint.ToString();
             MessageFormat msg = new MessageFormat(msgStr, ipAddress, MsgType.Send);
             if (OnSendCompletedEvent != null) OnSendCompletedEvent(msg);        //调用UI方法处理
         }

         /// <summary>
         /// 接收消息回调处理
         /// </summary>
         /// <param name="e"></param>
         public void OnReceiveCompleted(SocketAsyncEventArgs e)
         {
             if (e.SocketError != SocketError.Success) return;   //判断消息的接收状态
             AsyncUserToken token = e.UserToken as AsyncUserToken;
             int lengthBuffer = e.BytesTransferred;      //获取接收的字节长度
             string ipAddress = token.UserSocket.RemoteEndPoint.ToString();
             MessageFormat msg = new MessageFormat();
             //如果接收的字节长度为0，则判断远端服务器关闭连接
             if (lengthBuffer <= )
             {
                 msg.msgStr = "远端服务器已经断开连接";
                 msg.ipStr = ipAddress;
                 msg.tag = MsgType.Handler;
                 if (OnDisconnectEvent != null) OnDisconnectEvent(msg);
                 CloseClientSocket(e);
             }
             else
             {
                 byte[] receiveBuffer = e.Buffer;
                 byte[] buffer = new byte[lengthBuffer];
                 Buffer.BlockCopy(receiveBuffer, , buffer, , lengthBuffer);
                 msg.msgStr = Encoding.Unicode.GetString(buffer);
                 msg.ipStr = ipAddress;
                 msg.tag = MsgType.Receive;
                 bool willRaiseEvent = token.UserSocket.ReceiveAsync(e);     //继续异步接收消息
                 if (!willRaiseEvent)
                 {
                     OnReceiveCompleted(e);
                 }
                 if (OnReceiveCompletedEvent != null) OnReceiveCompletedEvent(msg);        //调用UI方法处理
             }
         }

         private void CloseClientSocket(SocketAsyncEventArgs e)
         {
             AsyncUserToken token = e.UserToken as AsyncUserToken;
             try
             {
                 token.UserSocket.Shutdown(SocketShutdown.Send);
             }
             catch (Exception) { }
             dicSAEA.Remove(token.UserSocket.RemoteEndPoint.ToString());
             token.UserSocket.Close();

             maxClient.Release();
             rwPool.Push(e);
         }
     }

public class SocketServerManager

通过一个栈结构SocketAsyncEventArgsPool保存的SocketAsyncEventArgs对象是用于接收消息，为了做到双方通讯，我每次在接收到远端客户端连接时，就创建一个新的SocketAsyncEventArgs对象保存在Dictionary结构中，这样在消息发送是就可以根据Ip来发送给远程客户端。

客户端的实现比较简单，不用考虑多方的通讯：

     public class SocketClientManager
     {
         readonly Socket _socket;      //用于消息交互的socket对象
         readonly EndPoint _endPoint;      //远端地址
         readonly SocketAsyncEventArgs _saea;        //处理连接和接收SAEA对象
         //处理发送的SAEA处理，由于绑定不同的回调函数，因此需要不同的SAEA对象
         SocketAsyncEventArgs _sendSaea;         

         //处理UI的事件
         public delegate void OnEventCompletedHanlder(MessageFormat msgFormat);
         public event OnEventCompletedHanlder OnConnectedEvent;       //连接成功事件
         public event OnEventCompletedHanlder OnReceiveCompletedEvent;        //收到消息事件
         public event OnEventCompletedHanlder OnSendCompletedEvent;       //发送成功事件

         public SocketClientManager(string ip, int port)
         {
             _socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
             IPAddress ipAddress = IPAddress.Parse(ip);
             _endPoint = new IPEndPoint(ipAddress, port);
             _saea = new SocketAsyncEventArgs {RemoteEndPoint = _endPoint};
         }

         /// <summary>
         /// 开启进行远程连接
         /// </summary>
         public void Start()
         {
             _saea.Completed += OnConnectedCompleted;
             _socket.ConnectAsync(_saea);        //进行异步连接

         }

         /// <summary>
         /// 连接成功的事件回调函数
         /// </summary>
         /// <param name="sender"></param>
         /// <param name="e"></param>
         public void OnConnectedCompleted(object sender, SocketAsyncEventArgs e)
         {
             if (e.SocketError != SocketError.Success) return;
             Socket socket = sender as Socket;
             string ipRemote = socket.RemoteEndPoint.ToString();
             MessageFormat messageFormat = new MessageFormat(string.Format("连接服务器[{0}]成功！", ipRemote), socket.LocalEndPoint.ToString(), MsgType.Empty);
             if (OnConnectedEvent != null) OnConnectedEvent(messageFormat);

             //开启新的接受消息异步操作事件
             var receiveSaea = new SocketAsyncEventArgs();
             var receiveBuffer = new byte[ * ];
             receiveSaea.SetBuffer(receiveBuffer, , receiveBuffer.Length);       //设置消息的缓冲区大小
             receiveSaea.Completed += OnReceiveCompleted;         //绑定回调事件
             receiveSaea.RemoteEndPoint = _endPoint;
             _socket.ReceiveAsync(receiveSaea);
         }

         /// <summary>
         /// 接受消息的回调函数
         /// </summary>
         /// <param name="sender"></param>
         /// <param name="e"></param>
         public void OnReceiveCompleted(object sender, SocketAsyncEventArgs e)
         {
             if (e.SocketError == SocketError.OperationAborted) return;
             var socket = sender as Socket;
             MessageFormat messageFormat = new MessageFormat();
             if (e.SocketError == SocketError.Success &&e.BytesTransferred > )
             {
                 string ipAddress = socket.RemoteEndPoint.ToString();
                 int lengthBuffer = e.BytesTransferred;
                 byte[] receiveBuffer = e.Buffer;
                 byte[] buffer = new byte[lengthBuffer];
                 Buffer.BlockCopy(receiveBuffer, , buffer, , lengthBuffer);
                 messageFormat.msgStr = Encoding.Unicode.GetString(buffer);
                 messageFormat.ipStr = ipAddress;
                 messageFormat.tag = MsgType.Receive;;
                 socket.ReceiveAsync(e);
             }
             else if (e.SocketError == SocketError.ConnectionReset && e.BytesTransferred == )
             {
                 messageFormat.msgStr = "服务器已经断开连接";
                 messageFormat.ipStr = socket.RemoteEndPoint.ToString();
                 messageFormat.tag = MsgType.Handler;
             }
             else
             {
                 return;
             }
             if (OnReceiveCompletedEvent != null) OnReceiveCompletedEvent(messageFormat);
         }

         /// <summary>
         /// 发送消息回调函数
         /// </summary>
         /// <param name="sender"></param>
         /// <param name="e"></param>
         public void OnSendCompleted(object sender, SocketAsyncEventArgs e)
         {
             if (e.SocketError != SocketError.Success) return;
             var socket = sender as Socket;
             byte[] sendBuffer = e.Buffer;
             MessageFormat messageFormat = new MessageFormat(Encoding.Unicode.GetString(sendBuffer),socket.RemoteEndPoint.ToString(),MsgType.Send);
             if (OnSendCompletedEvent != null) OnSendCompletedEvent(messageFormat);
         }

         /// <summary>
         /// 断开连接
         /// </summary>
         public void OnDisConnect()
         {
             if (_socket != null)
             {
                 try
                 {
                     _socket.Shutdown(SocketShutdown.Both);
                 }
                 catch (SocketException ex)
                 {
                 }
                 finally
                 {
                     _socket.Close();
                 }
             }
         }

         /// <summary>
         /// 发送消息
         /// </summary>
         /// <param name="msg"></param>
         public void SendMsg(MessageFormat mf)
         {
             byte[] sendBuffer = Encoding.Unicode.GetBytes(string.Format("[length={0}]{1}", mf.msgStr.Length, mf.msgStr));
             if (_sendSaea == null)
             {
                 _sendSaea = new SocketAsyncEventArgs {RemoteEndPoint = _endPoint};
                 _sendSaea.Completed += OnSendCompleted;
             }
             _sendSaea.SetBuffer(sendBuffer, , sendBuffer.Length);
             if (_socket != null) _socket.SendAsync(_sendSaea);
         }
     }

public class SocketClientManager

同样是使用收发不同的SocketAsyncEventArgs对象。

另外，关于解决缓存容量不足以容纳一条消息的半包问题，这里使用了简单的字符处理类，这个类是复制自Jimmy Zhang的类RequestHandler，当然，方法还是不完善的，难以解决不同顺序的消息接受。

具体源码（.net4.5，vs2013）：具体源码 http://files.cnblogs.com/files/supheart/ServerBySocket.zip