上一次的博文说错了东西，幸好有园友指出。才把错误改正过来，顺便也把利用SocketAsyncEventArgs进行Socket异步通信这方面的知识整理一下。
之前看了网上的代码，每进行一次异步操作都new 一个SocketAsyncEventArgs对象，然后网友评论太浪费资源了，于是就误以为用BeginXXX进行Socket异步通信会更优，幸好有园友指出我的误区，再看了这篇文章《》之后才发现SocketAsyncEventArgs是.NET Framework 3.5才出现的，而IAsyncResult是.NET Framework 2.0出现的，单纯从这点来看，新出的东西总会比旧的东西有优越之处吧。在用了之后明显的感觉就是，SocketAsyncEventArgs可以重复利用，而IAsyncResult对象就每次BeginXXX调用一次，就会生成一个，同样的进行多次的接收和发送之后，使用SocketAsyncEventArgs的一直都是使用那么一两个对象；可IAsyncResult的就每Begin一次就创建一次，累计下来创建了对象的数量很明显有差别。但是本人在使用SocketAsyncEventArgs时有部分思想还是停留在之前用BeginXXX方式时的。下面逐一列举吧
同样也是定义了一个数据结构
1 class ConnectInfo2 {3 public ArrayList tmpList { get; set; }4 public SocketAsyncEventArgs SendArg { get; set; }5 public SocketAsyncEventArgs ReceiveArg { get; set; }6 public Socket ServerSocket{ get;set;}7 } 虽然SocketAsyncEventArgs可以重复利用，但我在整个程序里头总共使用了三个，一个用于Accept的，这个在Complete事件绑定的方法里释放资源了。另外两个分别用于发送和接收。ArrayList是暂存客户端发来的数据。
下面则是Main方法里的代码
1 IPEndPoint serverPoint = new IPEndPoint(IPAddress.Parse("127.0.0.1"), 8081); 2 Socket serverSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp); 3 4 serverSocket.Bind(serverPoint); 5 serverSocket.Listen(10); 6 7 Console.WriteLine("waiting for a client"); 8 SocketAsyncEventArgs e=new SocketAsyncEventArgs(); 9 e.Completed += new EventHandler (Accept_Completed);10 serverSocket.AcceptAsync(e);11 12 Console.ReadLine(); 个人感觉这部分与使用IAsyncReult的BeginXXX不同的就是不需要把客户端的Socket对象传到Accept的方法里。
接着是与Complete事件定义的方法定义，也就是Accept成功之后调用的方法
1 static void Accept_Completed(object sender, SocketAsyncEventArgs e) 2 { 3 Socket client = e.AcceptSocket; 4 Socket server = sender as Socket; 5 6 if (sender == null) return; 7 8 SocketAsyncEventArgs sendArg = new SocketAsyncEventArgs(); 9 SocketAsyncEventArgs receciveArg = new SocketAsyncEventArgs();10 11 ConnectInfo info = new ConnectInfo();12 info.tmpList = new ArrayList();13 info.SendArg = sendArg;14 info.ReceiveArg = receciveArg;15 info.ServerSocket=server;16 17 byte[] sendbuffers=Encoding.ASCII.GetBytes("hello world");18 sendArg.SetBuffer(sendbuffers, 0, sendbuffers.Length);19 20 sendbuffers=new byte[1024];21 receciveArg.SetBuffer(sendbuffers, 0, 1024);22 receciveArg.UserToken = info;23 receciveArg.Completed += new EventHandler (Rececive_Completed);24 25 client.SendAsync(sendArg);26 client.ReceiveAsync(receciveArg);27 28 e.Dispose();29 } 由于有sender这个参数，就可以获取服务端的Socket对象，在这里把两个SocektAsyncEventArgs对象构造出来， 在构造了一个ConnectInfo的对象记录本次通信的一些信息。ConnectInfo这部分与BeginXXX的类似。但把ConnectInfo的对象传过去给相应的Complete事件处理方法里面就有所不同了，SocketAsyncEventArgs是用UserToken属性，把关联的用户或应用程序对象传过去。设置Buffer就用SetBuffer方法。发送消息并没有绑定Complete方法，感觉绑了也没什么用。
最后上的是接受成功的代码
1 static void Rececive_Completed(object sender, SocketAsyncEventArgs e) 2 { 3 ConnectInfo info = e.UserToken as ConnectInfo; 4 if (info == null) return; 5 Socket client = sender as Socket; 6 if (client == null) return; 7 8 if (e.SocketError== SocketError.Success) 9 {10 int rec = e.BytesTransferred;11 //收不到数据表明客户端终止了通信12 //关闭相关的socket和释放资源13 if (rec == 0)14 {15 client.Close();16 client.Dispose();17 18 info.ReceiveArg.Dispose();19 info.SendArg.Dispose();20 21 if (info.ServerSocket != null)22 {23 info.ServerSocket.Close();24 info.ServerSocket.Dispose();25 }26 return;27 }28 29 byte[] datas=e.Buffer;30 31 //如果数据还没接收完的就把已接收的数据暂存32 //新开辟一个足够大的buffer来接收数据33 if (client.Available > 0)34 {35 for (int i = 0; i < rec; i++)36 info.tmpList.Add(datas[i]);37 Array.Clear(datas, 0, datas.Length);38 39 datas = new byte[client.Available];40 e.SetBuffer(datas, 0, datas.Length);41 client.ReceiveAsync(e);42 }43 else44 {45 //检查暂存数据的ArrayList中有没有数据，有就和本次的数据合并46 if (info.tmpList.Count > 0)47 {48 for (int i = 0; i < rec; i++)49 info.tmpList.Add(datas[i]);50 datas = info.tmpList.ToArray(typeof(byte)) as byte[];51 rec = datas.Length;52 }53 54 //对接收的完整数据进行简单处理，回发给客户端55 string msg = Encoding.ASCII.GetString(datas).Trim('\0');56 if (msg.Length > 10) msg = msg.Substring(0, 10) + "...";57 msg = string.Format("rec={0}\r\nmessage={1}", rec, msg);58 59 info.SendArg.SetBuffer(Encoding.ASCII.GetBytes(msg),0,msg.Length);60 client.SendAsync(info.SendArg);61 62 //如果buffer过大的，把它换成一个小的63 info.tmpList.Clear();64 if (e.Buffer.Length > 1024)65 {66 datas = new byte[1024];67 e.SetBuffer(datas, 0, datas.Length);68 }69 70 //再次进行异步接收71 client.ReceiveAsync(e);72 } 73 }74 } 这里也是考虑到接收数据量过大造成下次接收时粘包，也做类似上篇博文中的那样处理。在接收过大的数据时需要分两次读取，用一个ArrayList暂时存放已经读取的数据。在上一篇博文有位园友提了一下内存消耗的问题，于是这次我缩减了一下byte[]的使用量。这样应该消耗不再大了吧！
尽管这次我做的感觉比上次的要好，但对于在行的人应该会挑得出不少毛病出来的。上面有什么说错的请各位指出，有什么说漏的，请各位提点，多多指导。谢谢！
完整代码 1 class ConnectInfo 2 { 3 public ArrayList tmpList { get; set; } 4 public SocketAsyncEventArgs SendArg { get; set; } 5 public SocketAsyncEventArgs ReceiveArg { get; set; } 6 public Socket ServerSocket{ get;set;} 7 } 8 9 class EventSocektServer 10 { 11 static void Main() 12 { 13 IPEndPoint serverPoint = new IPEndPoint(IPAddress.Parse("127.0.0.1"), 8081); 14 Socket serverSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp); 15 16 serverSocket.Bind(serverPoint); 17 serverSocket.Listen(10); 18 19 Console.WriteLine("waiting for a client"); 20 SocketAsyncEventArgs e=new SocketAsyncEventArgs(); 21 e.Completed += new EventHandler (Accept_Completed); 22 serverSocket.AcceptAsync(e); 23 24 Console.ReadLine(); 25 } 26 27 static void Accept_Completed(object sender, SocketAsyncEventArgs e) 28 { 29 Socket client = e.AcceptSocket; 30 Socket server = sender as Socket; 31 32 if (sender == null) return; 33 34 SocketAsyncEventArgs sendArg = new SocketAsyncEventArgs(); 35 SocketAsyncEventArgs receciveArg = new SocketAsyncEventArgs(); 36 37 ConnectInfo info = new ConnectInfo(); 38 info.tmpList = new ArrayList(); 39 info.SendArg = sendArg; 40 info.ReceiveArg = receciveArg; 41 info.ServerSocket=server; 42 43 byte[] sendbuffers=Encoding.ASCII.GetBytes("hello world"); 44 sendArg.SetBuffer(sendbuffers, 0, sendbuffers.Length); 45 46 sendbuffers=new byte[1024]; 47 receciveArg.SetBuffer(sendbuffers, 0, 1024); 48 receciveArg.UserToken = info; 49 receciveArg.Completed += new EventHandler (Rececive_Completed); 50 51 client.SendAsync(sendArg); 52 client.ReceiveAsync(receciveArg); 53 54 e.Dispose(); 55 } 56 57 static void Rececive_Completed(object sender, SocketAsyncEventArgs e) 58 { 59 ConnectInfo info = e.UserToken as ConnectInfo; 60 if (info == null) return; 61 Socket client = sender as Socket; 62 if (client == null) return; 63 64 if (e.SocketError == SocketError.Success) 65 { 66 int rec = e.BytesTransferred; 67 //收不到数据表明客户端终止了通信 68 //关闭相关的socket和释放资源 69 if (rec == 0) 70 { 71 client.Close(); 72 client.Dispose(); 73 74 info.ReceiveArg.Dispose(); 75 info.SendArg.Dispose(); 76 77 if (info.ServerSocket != null) 78 { 79 info.ServerSocket.Close(); 80 info.ServerSocket.Dispose(); 81 } 82 return; 83 } 84 85 byte[] datas = e.Buffer; 86 87 //如果数据还没接收完的就把已接收的数据暂存 88 //新开辟一个足够大的buffer来接收数据 89 if (client.Available > 0) 90 { 91 for (int i = 0; i < rec; i++) 92 info.tmpList.Add(datas[i]); 93 Array.Clear(datas, 0, datas.Length); 94 95 datas = new byte[client.Available]; 96 e.SetBuffer(datas, 0, datas.Length); 97 client.ReceiveAsync(e); 98 } 99 else100 {101 //检查暂存数据的ArrayList中有没有数据，有就和本次的数据合并102 if (info.tmpList.Count > 0)103 {104 for (int i = 0; i < rec; i++)105 info.tmpList.Add(datas[i]);106 datas = info.tmpList.ToArray(typeof(byte)) as byte[];107 rec = datas.Length;108 }109 110 //对接收的完整数据进行简单处理，回发给客户端111 string msg = Encoding.ASCII.GetString(datas).Trim('\0');112 if (msg.Length > 10) msg = msg.Substring(0, 10) + "...";113 msg = string.Format("rec={0}\r\nmessage={1}", rec, msg);114 115 info.SendArg.SetBuffer(Encoding.ASCII.GetBytes(msg), 0, msg.Length);116 client.SendAsync(info.SendArg);117 118 //如果buffer过大的，把它换成一个小的119 info.tmpList.Clear();120 if (e.Buffer.Length > 1024)121 {122 datas = new byte[1024];123 e.SetBuffer(datas, 0, datas.Length);124 }125 126 //再次进行异步接收127 client.ReceiveAsync(e);128 }129 }130 }