Socket

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（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。

1 　　SocketAsyncEventArgs saea = new SocketAsyncEventArgs();
2 　　//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)：
3 　　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

1 　　byte[] buffer = new byte[1024];
2 　　saea.SetBuffer(buffer, 0, buffer.Length);    //设置缓冲区
3 　　saea.Completed += new EventHandler<SocketAsyncEventArgs>(MethodName);    //设置回调方法
4 　　saea.RemoteEndPoint = new IPEndPoint(IPAddress.Any,1234);    //设置远端连接节点，一般用于接收消息
5 　　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。

 1 　　//这是调用套接字的方法，即socket调用的方法：
 2 　　Socket socket = saea.AcceptSocket;
 3 　　socket.ConnectAsync(saea);     //异步进行连接
 4 　　socket.AcceptAsync(saea);     //异步接收连接
 5 　　socket.ReceiveAsync(saea);     //异步接收消息
 6 　　socket.SendAsync(saea);     //异步发送消息
 7 　　//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
 8 　　bool willRaiseEvent = socket.ReceiveAsync(saea); //继续异步接收消息
 9 　　if (!willRaiseEvent)
10 　　{
11 　　　　MethodName(saea);
12 　　}

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，
　　

1 saea.AcceptSocket = null;//重新监听    
2 socket.ReceiveAsync(saea);//重新接收
3 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：

  1     public class SocketServerManager
  2     {
  3         readonly Socket _socket;        //监听Socket
  4         readonly EndPoint _endPoint;
  5         private const int Backlog = 100;     //允许连接数目
  6         private int byteSize = 64;
  7 
  8         //同时UI界处理的事件
  9         public delegate void OnEventCompletedHanlder(MessageFormat msg);
 10         public event OnEventCompletedHanlder OnReceiveCompletedEvent;
 11         public event OnEventCompletedHanlder OnSendCompletedEvent;
 12         public event OnEventCompletedHanlder OnConnectedEvent;
 13         public event OnEventCompletedHanlder OnDisconnectEvent;
 14         public event OnEventCompletedHanlder OnNotConnectEvent;
 15 
 16         //private BufferManager bufferManager;        //消息缓存管理
 17         SocketAsyncEventArgsPool rwPool;              //SAEA池
 18         private Semaphore maxClient;
 19         private Dictionary<string, SocketAsyncEventArgs> dicSAEA = null; 
 20 
 21         public SocketServerManager(string ip, int port)
 22         {
 23             _socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
 24             IPAddress ipAddress = IPAddress.Parse(ip);
 25             _endPoint = new IPEndPoint(ipAddress, port);
 26             //bufferManager = new BufferManager(totalBytes, byteSize);
 27             maxClient = new Semaphore(Backlog, Backlog);
 28             Init();
 29         }
 30 
 31         public void Init()
 32         {
 33             //bufferManager.InitBuffer();
 34             SocketAsyncEventArgs rwEventArgs;
 35             rwPool = new SocketAsyncEventArgsPool(Backlog);
 36             dicSAEA = new Dictionary<string, SocketAsyncEventArgs>();
 37             for (int i = 0; i < 100; i++)
 38             {
 39                 rwEventArgs = new SocketAsyncEventArgs();
 40                 rwEventArgs.Completed += new EventHandler<SocketAsyncEventArgs>(IO_Completed);
 41                rwEventArgs.UserToken = new AsyncUserToken();
 42 
 43                 rwEventArgs.SetBuffer(new byte[byteSize],0,byteSize);
 44                 //bufferManager.SetBuffer(rwEventArgs);
 45 
 46                 rwPool.Push(rwEventArgs);
 47             }
 48         }
 49 
 50         /// <summary>
 51         /// 开启Socket监听
 52         /// </summary>
 53         public void Start()
 54         {
 55             _socket.Bind(_endPoint);        //绑定本地地址进行监听
 56             _socket.Listen(Backlog);        //设置监听数量
 57 
 58             StartAccept(null);
 59         }
 60 
 61         public void StartAccept(SocketAsyncEventArgs acceptEventArg)
 62         {
 63             if (acceptEventArg == null)
 64             {
 65                 acceptEventArg = new SocketAsyncEventArgs();
 66                 acceptEventArg.Completed += new EventHandler<SocketAsyncEventArgs>(OnConnectedCompleted);
 67             }
 68             else
 69             {
 70                 acceptEventArg.AcceptSocket = null;
 71             }
 72 
 73             maxClient.WaitOne();
 74             bool willRaiseEvent = _socket.AcceptAsync(acceptEventArg);
 75             if (!willRaiseEvent)
 76             {
 77                 ProcessAccept(acceptEventArg);
 78             }
 79         }
 80 
 81         private void ProcessAccept(SocketAsyncEventArgs e)
 82         {
 83             if (e.SocketError != SocketError.Success) return;       //异步处理失败，不做处理
 84             SocketAsyncEventArgs saea = rwPool.Pop();
 85             AsyncUserToken token = saea.UserToken as AsyncUserToken;
 86             token.UserSocket = e.AcceptSocket;       //获取远端对话Socket对象
 87             string ipRemote = token.UserSocket.RemoteEndPoint.ToString();
 88             string ip = token.UserSocket.RemoteEndPoint.ToString();
 89             MessageFormat msg = new MessageFormat(string.Format("远程地址[{0}]成功连接到本地", ipRemote), ip, MsgType.Empty);
 90             msg.tag = MsgType.Empty;
 91             if (OnConnectedEvent != null) OnConnectedEvent(msg);            //调用UI方法处理
 92 
 93             //连接成功后，发送消息通知远程客户端
 94             //OnSend("Connected Success !", _sendSocket.RemoteEndPoint);
 95             SocketAsyncEventArgs sendArgs = new SocketAsyncEventArgs();
 96             sendArgs.RemoteEndPoint = token.UserSocket.RemoteEndPoint;
 97             sendArgs.Completed += new EventHandler<SocketAsyncEventArgs>(IO_Completed);
 98             sendArgs.UserToken = saea.UserToken;
 99             dicSAEA.Add(token.UserSocket.RemoteEndPoint.ToString(), sendArgs);
100             bool willRaiseEvent = e.AcceptSocket.ReceiveAsync(saea);
101             if (!willRaiseEvent)
102             {
103                 OnReceiveCompleted(saea);
104             }
105 
106             StartAccept(e);
107         }
108 
109         /// <summary>
110         /// 远端地址连接本地成功的回调
111         /// </summary>
112         /// <param name="sender"></param>
113         /// <param name="e"></param>
114         public void OnConnectedCompleted(object sender, SocketAsyncEventArgs e)
115         {
116             ProcessAccept(e);
117         }
118 
119         public void IO_Completed(object sender, SocketAsyncEventArgs e)
120         {
121             switch (e.LastOperation)
122             {
123                 case SocketAsyncOperation.Receive:
124                     OnReceiveCompleted(e);
125                     break;
126                 case SocketAsyncOperation.Send:
127                     OnSendCompleted(e);
128                     break;
129                 default:
130                     throw new ArgumentException("The last operation completed on the socket was not a receive or send");
131             }   
132         }
133 
134         /// <summary>
135         /// 执行异步发送消息
136         /// </summary>
137         /// <param name="msg">消息内容</param>
138         /// <param name="ip">发送远端地址</param>
139         public void OnSend(MessageFormat mf)
140         {
141             if (!dicSAEA.ContainsKey(mf.ipStr))
142             {
143                 if (OnNotConnectEvent != null)
144                 {
145                     OnNotConnectEvent(new MessageFormat("不存在此连接客户端","",MsgType.Empty));
146                     return;
147                 }
148             }
149             SocketAsyncEventArgs saea = dicSAEA[mf.ipStr];
150             AsyncUserToken token = saea.UserToken as AsyncUserToken;
151             if (saea == null) return;
152             //saea.SetBuffer(sendBuffer, 0, sendBuffer.Length);  //设置SAEA的buffer消息内容
153             byte[] sendBuffer = Encoding.Unicode.GetBytes(string.Format("[length={0}]{1}", mf.msgStr.Length, mf.msgStr));
154             saea.SetBuffer(sendBuffer, 0, sendBuffer.Length);
155             bool willRaiseEvent = token.UserSocket.SendAsync(saea);
156             if (!willRaiseEvent)
157             {
158                 OnSendCompleted(saea);
159             }
160         }
161 
162         /// <summary>
163         /// 发送消息回调处理
164         /// </summary>
165         /// <param name="sender"></param>
166         /// <param name="e"></param>
167         public void OnSendCompleted(SocketAsyncEventArgs e)
168         {
169             AsyncUserToken token = e.UserToken as AsyncUserToken;
170             byte[] sendBuffer = e.Buffer;
171             string msgStr = Encoding.Unicode.GetString(sendBuffer);
172             string ipAddress = token.UserSocket.RemoteEndPoint.ToString();
173             MessageFormat msg = new MessageFormat(msgStr, ipAddress, MsgType.Send);
174             if (OnSendCompletedEvent != null) OnSendCompletedEvent(msg);        //调用UI方法处理
175         }
176 
177         /// <summary>
178         /// 接收消息回调处理
179         /// </summary>
180         /// <param name="e"></param>
181         public void OnReceiveCompleted(SocketAsyncEventArgs e)
182         {
183             if (e.SocketError != SocketError.Success) return;   //判断消息的接收状态
184             AsyncUserToken token = e.UserToken as AsyncUserToken;
185             int lengthBuffer = e.BytesTransferred;      //获取接收的字节长度
186             string ipAddress = token.UserSocket.RemoteEndPoint.ToString();
187             MessageFormat msg = new MessageFormat();
188             //如果接收的字节长度为0，则判断远端服务器关闭连接
189             if (lengthBuffer <= 0)
190             {
191                 msg.msgStr = "远端服务器已经断开连接";
192                 msg.ipStr = ipAddress;
193                 msg.tag = MsgType.Handler;
194                 if (OnDisconnectEvent != null) OnDisconnectEvent(msg);
195                 CloseClientSocket(e);
196             }
197             else
198             {
199                 byte[] receiveBuffer = e.Buffer;
200                 byte[] buffer = new byte[lengthBuffer];
201                 Buffer.BlockCopy(receiveBuffer, 0, buffer, 0, lengthBuffer);
202                 msg.msgStr = Encoding.Unicode.GetString(buffer);
203                 msg.ipStr = ipAddress;
204                 msg.tag = MsgType.Receive;
205                 bool willRaiseEvent = token.UserSocket.ReceiveAsync(e);     //继续异步接收消息
206                 if (!willRaiseEvent)
207                 {
208                     OnReceiveCompleted(e);
209                 }
210                 if (OnReceiveCompletedEvent != null) OnReceiveCompletedEvent(msg);        //调用UI方法处理
211             }
212         }
213 
214         private void CloseClientSocket(SocketAsyncEventArgs e)
215         {
216             AsyncUserToken token = e.UserToken as AsyncUserToken;
217             try
218             {
219                 token.UserSocket.Shutdown(SocketShutdown.Send);
220             }
221             catch (Exception) { }
222             dicSAEA.Remove(token.UserSocket.RemoteEndPoint.ToString());
223             token.UserSocket.Close();
224 
225             maxClient.Release();
226             rwPool.Push(e);
227         }
228     }

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：

  1     public class SocketClientManager
  2     {
  3         readonly Socket _socket;      //用于消息交互的socket对象
  4         readonly EndPoint _endPoint;      //远端地址
  5         readonly SocketAsyncEventArgs _saea;        //处理连接和接收SAEA对象
  6         //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
  7         SocketAsyncEventArgs _sendSaea;         
  8 
  9         //处理UI的事件
 10         public delegate void OnEventCompletedHanlder(MessageFormat msgFormat);
 11         public event OnEventCompletedHanlder OnConnectedEvent;       //连接成功事件
 12         public event OnEventCompletedHanlder OnReceiveCompletedEvent;        //收到消息事件
 13         public event OnEventCompletedHanlder OnSendCompletedEvent;       //发送成功事件
 14 
 15         public SocketClientManager(string ip, int port)
 16         {
 17             _socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
 18             IPAddress ipAddress = IPAddress.Parse(ip);
 19             _endPoint = new IPEndPoint(ipAddress, port);
 20             _saea = new SocketAsyncEventArgs {RemoteEndPoint = _endPoint};
 21         }
 22 
 23         /// <summary>
 24         /// 开启进行远程连接
 25         /// </summary>
 26         public void Start()
 27         {
 28             _saea.Completed += OnConnectedCompleted;
 29             _socket.ConnectAsync(_saea);        //进行异步连接
 30 
 31         }
 32 
 33         /// <summary>
 34         /// 连接成功的事件回调函数
 35         /// </summary>
 36         /// <param name="sender"></param>
 37         /// <param name="e"></param>
 38         public void OnConnectedCompleted(object sender, SocketAsyncEventArgs e)
 39         {
 40             if (e.SocketError != SocketError.Success) return;
 41             Socket socket = sender as Socket;
 42             string ipRemote = socket.RemoteEndPoint.ToString();
 43             MessageFormat messageFormat = new MessageFormat(string.Format("连接服务器[{0}]成功！", ipRemote), socket.LocalEndPoint.ToString(), MsgType.Empty);
 44             if (OnConnectedEvent != null) OnConnectedEvent(messageFormat);
 45 
 46             //开启新的接受消息异步操作事件
 47             var receiveSaea = new SocketAsyncEventArgs();
 48             var receiveBuffer = new byte[1024 * 4];
 49             receiveSaea.SetBuffer(receiveBuffer, 0, receiveBuffer.Length);       //设置消息的缓冲区大小
 50             receiveSaea.Completed += OnReceiveCompleted;         //绑定回调事件
 51             receiveSaea.RemoteEndPoint = _endPoint;
 52             _socket.ReceiveAsync(receiveSaea);
 53         }
 54 
 55         /// <summary>
 56         /// 接受消息的回调函数
 57         /// </summary>
 58         /// <param name="sender"></param>
 59         /// <param name="e"></param>
 60         public void OnReceiveCompleted(object sender, SocketAsyncEventArgs e)
 61         {
 62             if (e.SocketError == SocketError.OperationAborted) return;
 63             var socket = sender as Socket;
 64             MessageFormat messageFormat = new MessageFormat();
 65             if (e.SocketError == SocketError.Success &&e.BytesTransferred > 0)
 66             {
 67                 string ipAddress = socket.RemoteEndPoint.ToString();
 68                 int lengthBuffer = e.BytesTransferred;
 69                 byte[] receiveBuffer = e.Buffer;
 70                 byte[] buffer = new byte[lengthBuffer];
 71                 Buffer.BlockCopy(receiveBuffer, 0, buffer, 0, lengthBuffer);
 72                 messageFormat.msgStr = Encoding.Unicode.GetString(buffer);
 73                 messageFormat.ipStr = ipAddress;
 74                 messageFormat.tag = MsgType.Receive;;
 75                 socket.ReceiveAsync(e);
 76             }
 77             else if (e.SocketError == SocketError.ConnectionReset && e.BytesTransferred == 0)
 78             {
 79                 messageFormat.msgStr = "服务器已经断开连接";
 80                 messageFormat.ipStr = socket.RemoteEndPoint.ToString();
 81                 messageFormat.tag = MsgType.Handler;
 82             }
 83             else
 84             {
 85                 return;
 86             }
 87             if (OnReceiveCompletedEvent != null) OnReceiveCompletedEvent(messageFormat);
 88         }
 89 
 90         /// <summary>
 91         /// 发送消息回调函数
 92         /// </summary>
 93         /// <param name="sender"></param>
 94         /// <param name="e"></param>
 95         public void OnSendCompleted(object sender, SocketAsyncEventArgs e)
 96         {
 97             if (e.SocketError != SocketError.Success) return;
 98             var socket = sender as Socket;
 99             byte[] sendBuffer = e.Buffer;
100             MessageFormat messageFormat = new MessageFormat(Encoding.Unicode.GetString(sendBuffer),socket.RemoteEndPoint.ToString(),MsgType.Send);
101             if (OnSendCompletedEvent != null) OnSendCompletedEvent(messageFormat);
102         }
103 
104         /// <summary>
105         /// 断开连接
106         /// </summary>
107         public void OnDisConnect()
108         {
109             if (_socket != null)
110             {
111                 try
112                 {
113                     _socket.Shutdown(SocketShutdown.Both);
114                 }
115                 catch (SocketException ex)
116                 {
117                 }
118                 finally
119                 {
120                     _socket.Close();
121                 }
122             }
123         }
124 
125         /// <summary>
126         /// 发送消息
127         /// </summary>
128         /// <param name="msg"></param>
129         public void SendMsg(MessageFormat mf)
130         {
131             byte[] sendBuffer = Encoding.Unicode.GetBytes(string.Format("[length={0}]{1}", mf.msgStr.Length, mf.msgStr));
132             if (_sendSaea == null)
133             {
134                 _sendSaea = new SocketAsyncEventArgs {RemoteEndPoint = _endPoint};
135                 _sendSaea.Completed += OnSendCompleted;
136             }
137             _sendSaea.SetBuffer(sendBuffer, 0, sendBuffer.Length);
138             if (_socket != null) _socket.SendAsync(_sendSaea);
139         }
140     }

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 https://files.cnblogs.com/files/wuzehao/ServerBySocket.zip