前言 TCP通信承载着一个应用程序的数据传输，而在Unity的开发当中，TCP通信也是重中之重，不懂TCP通信、不懂网络编程，日常开发工作就会变得尤为艰难。
本篇文章我就详细的记录一下我所了解的Unity中的TCP通信，并逐步去实现一个比较常用的TCP通信框架。
首先了解两条比较基础的东西：
具体概念不多做介绍了，如果对此有迷惑可以看这篇文章 。
下面开始使用Socket一步一步实现Unity客户端的TCP连接。
构建Socket对象 要实现C#的TCP通信，需要使用System.Net.Sockets这个命名空间下的Socket类：
1 Socket socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
可以看到，创建Socket对象需要3个参数，下面介绍这个3个参数的含义。
AddressFamily 枚举 枚举名 值 含义 Unknown -1 未知的地址族 Unspecified 0 未指定的地址族 Unix 1 Unix本地到主机地址 InterNetwork 2 IP版本4的地址 ImpLink 3 ARPANET IMP地址 Pup 4 PUP协议的地址 Chaos 5 MIT CHAOS协议的地址 NS 6 Xerox NS协议的地址 Ipx 6 IPX或SPX地址 Iso 7 ISO协议的地址 Osi 7 OSI协议的地址 Ecma 8 欧洲计算机制造商协会(ECMA)地址 DataKit 9 Datakit协议的地址 Ccitt 10 CCITT协议(如 X.25)的地址 Sna 11 IBM SNA地址 DecNet 12 DECnet地址 DataLink 13 直接数据链接接口地址 Lat 14 LAT地址 HyperChannel 15 NSC Hyperchannel地址 AppleTalk 16 AppleTalk NetBios 17 NetBios地址 VoiceView 18 VoiceView地址 FireFox 19 FireFox地址 Banyan 21 Banyan地址 Atm 22 本机ATM服务地址 InterNetworkV6 23 IP版本6的地址 Cluster 24 Microsoft群集产品的地址 Ieee12844 25 IEEE 1284.4工作组地址 Irda 26 IrDA地址 NetworkDesigners 28 支持网络设计器OSI网关的协议的地址 Max 29 MAX地址
SocketType 枚举 枚举名 值 含义 Unknown -1 指定未知的Socket类型 Stream 1 支持可靠、双向、基于连接的字节流，而不重复数据，也不保留边界。此类型的Socket与单个对方主机通信，并且在通信开始之前需要建立远程主机连接。Stream使用传输控制协议 (ProtocolType.Tcp)和AddressFamily。InterNetwork地址族 Dgram 2 支持数据报，即最大长度固定（通常很小）的无连接、不可靠消息。消息可能会丢失或重复并可能在到达时不按顺序排列。Socket类型的Dgram在发送和接收数据之前不需要任何连接，并且可以与多个对方主机进行通信。Dgram使用数据报协议(ProtocolType.Udp)和AddressFamily.InterNetwork地址族 Raw 3 支持对基础传输协议的访问。通过使用Raw，可以使用Internet控制消息协议(ProtocolType.Icmp)和Internet组管理协议(ProtocolType.Igmp)这样的协议来进行通信。在发送时，您的应用程序必须提供完整的IP标头。所接收的数据报在返回时会保持其IP标头和选项不变 Rdm 4 支持无连接、面向消息、以可靠方式发送的消息，并保留数据中的消息边界。RDM(以可靠方式发送的消息)消息会依次到达，不会重复。此外，如果消息丢失，将会通知发送方。如果使用Rdm初始化Socket，则在发送和接收数据之前无需建立远程主机连接。利用Rdm，您可以与多个对方主机进行通信 Seqpacket 5 在网络上提供排序字节流的面向连接且可靠的双向传输。Seqpacket不重复数据，它在数据流中保留边界。Seqpacket类型的Socket与单个对方主机通信，并且在通信开始之前需要建立远程主机连接
ProtocolType 枚举 枚举名 值 含义 Unknown -1 未知协议 Icmp -1 网际消息控制协议 Unspecified 0 未指定的协议 IP 0 网际协议 IPv6HopByHopOptions 0 IPv6 逐跳选项头 Igmp 2 网际组管理协议 Ggp 3 网关到网关协议 IPv4 4 Internet协议版本4 Tcp 6 传输控制协议 Pup 12 PARC通用数据包协议 Udp 17 用户数据报协议 Idp 22 Internet数据报协议 IPv6 41 Internet协议版本6(IPv6) IPv6RoutingHeader 43 IPv6路由头 IPv6FragmentHeader 44 IPv6片段头 IPSecEncapsulatingSecurityPayload 50 IPv6封装式安全措施负载头 IPSecAuthenticationHeader 51 IPv6 身份验证头。有关详细信息，请参阅https://www.ietf.org上的 RFC 2292，第 2.2.1 节 IcmpV6 58 用于IPv6的Internet 控制消息协议 IPv6NoNextHeader 59 IPv6 No Next头 IPv6DestinationOptions 60 IPv6目标选项头 ND 77 网络磁盘协议(非正式) Raw 255 原始IP数据包协议 Ipx 1000 Internet数据包交换协议 Spx 1256 顺序包交换协议 SpxII 1257 顺序包交换协议第 2 版
上面分别列举了3个枚举所有的值及对应的含义，实际上
1 Socket socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
这行代码的意思就是使用IPV4地址，全双工安全可靠通讯，TCP协议来创建一个Socket对象。
建立连接 建立连接的整个过程是：
Connect 调用Connect方法连接服务器，连接失败则跳出
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 public void Connect (string ip, int port{ m_IP = ip; m_Port = port; m_Socket = new Socket(AddressFamily.InterNetwork,SocketType.Stream,ProtocolType.Tcp); try { m_Socket.Connect(new IPEndPoint(IPAddress.Parse(ip), port)); m_ReceiveStream = new MemoryStream(); m_IsConnected = true ; StartReceive(); if (OnConnectSuccess != null ) { OnConnectSuccess(); } Debug.Log("连接服务器:" + ip + "成功！" ); } catch (Exception e) { if (OnConnectFail != null ) { OnConnectFail(); } Debug.Log(e.Message); } }
BeginReceive 使用BeginReceive方法，使当前进入阻塞状态，等待接收服务端发送的消息，成功接收到消息后对应的数据会写入到一个字节流中等待处理
1 2 3 4 5 private void StartReceive (){ if (!m_IsConnected) return ; m_Socket.BeginReceive(m_ReceiveBuffer,0 ,m_ReceiveBuffer.Length,SocketFlags.None,OnReceive, m_Socket); }
EndReceive 当接收到消息时，调用EndReceive方法结束本次数据接收，然后开始解包，解包成功再次调用BeginReceive方法开始新一轮数据接收
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 private void OnReceive (IAsyncResult ir ){ if (!m_IsConnected) return ; try { int length = m_Socket.EndReceive(ir); if (length < 1 ) { Debug.Log("服务器断开连接" ); Close(); return ; } m_ReceiveStream.Position = m_ReceiveStream.Length; m_ReceiveStream.Write(m_ReceiveBuffer, 0 , length); if (m_ReceiveStream.Length < 4 ) { StartReceive(); return ; } while (true ) { m_ReceiveStream.Position = 0 ; byte [] msgLenBuffer = new byte [2 ]; m_ReceiveStream.Read(msgLenBuffer, 0 , 2 ); int msgLen = BitConverter.ToUInt16(msgLenBuffer, 0 ) + 2 ; int fullLen = 2 + msgLen; if (m_ReceiveStream.Length < fullLen) { break ; } byte [] msgBuffer = new byte [msgLen]; m_ReceiveStream.Position = 2 ; m_ReceiveStream.Read(msgBuffer, 0 , msgLen); lock (m_ReceiveQueue) { m_ReceiveQueue.Enqueue(msgBuffer); } int remainLen = (int )m_ReceiveStream.Length - fullLen; if (remainLen < 1 ) { m_ReceiveStream.Position = 0 ; m_ReceiveStream.SetLength(0 ); break ; } m_ReceiveStream.Position = fullLen; byte [] remainBuffer = new byte [remainLen]; m_ReceiveStream.Read(remainBuffer, 0 , remainLen); m_ReceiveStream.Position = 0 ; m_ReceiveStream.SetLength(0 ); m_ReceiveStream.Write(remainBuffer, 0 , remainLen); remainBuffer = null ; } } catch (Exception e) { Debug.Log("++服务器断开连接," + e.Message); Close(); return ; } StartReceive(); }
这里包含了粘包处理的代码。粘包问题可能比较难理解，这里进行一下分析：
什么是粘包：一次通讯包含了多条数据
为什么会产生粘包：当数据包很小时，Tcp协议会把较小的数据包合并到一起，使一些零散的小包通过一次通讯就可以传输完毕。
如何解决粘包：这里采用我最熟悉的也是最常用的方式，包体定长。包体定长就是指无论客户端还是服务端，在发送数据包之前，需要把这个包的长度写入到包头，在解包的时候首先读出包体长度msgLen，通过计算得出本次通讯实际的包体长度fullLen = msgLen+2，如果接收到的包体长度m_ReceiverBuffer.Length大于实际长度fullLen，则可以认为发生粘包，此时只处理msgLen这个长度的包即可，剩余的数据重新写入m_ReceiverBuffer，下一次接收的包会和这个剩余包重新组成一个完整包。
得到真实的数据后，把真实数据入队，并在Unity主线程的update中去处理
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 private void Update (){ if (m_IsConnected) CheckReceiveBuffer(); } private void CheckReceiveBuffer (){ while (true ) { if (m_CheckCount > 5 ) { m_CheckCount = 0 ; break ; } m_CheckCount++; lock (m_ReceiveQueue) { if (m_ReceiveQueue.Count < 1 ) { break ; } byte [] buffer = m_ReceiveQueue.Dequeue(); byte [] msgContent = new byte [buffer.Length - 2 ]; ushort msgCode = 0 ; using (MemoryStream ms = new MemoryStream(buffer)) { byte [] msgCodeBuffer = new byte [2 ]; ms.Read(msgCodeBuffer, 0 , msgCodeBuffer.Length); msgCode = BitConverter.ToUInt16(msgCodeBuffer, 0 ); ms.Read(msgContent, 0 , msgContent.Length); } if (onReceive != null ) { onReceive(msgCode, msgContent); } } } }
为什么需要在Update中去处理呢？因为BeginReceive是多线程异步接收到数据的，而unity的api不允许在非主线程中去访问，所以要把在非主线程中得到的数据入队，并在unity主线程中去处理。
发送数据 上面提到过为了解决粘包，需要把消息包体进行定长，所以发包第一步就是先把包体长度写入数据流，然后把消息编码写入数据流，最后才写入真实的要发送的数据内容，调用BeginSend进行异步发送。
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 public void Send (ushort msgCode, byte [] buffer{ if (!m_IsConnected) return ; byte [] sendMsgBuffer = null ; using (MemoryStream ms = new MemoryStream()) { int msgLen = buffer.Length; byte [] lenBuffer = BitConverter.GetBytes((ushort )msgLen); byte [] msgCodeBuffer = BitConverter.GetBytes(msgCode); ms.Write(lenBuffer, 0 , lenBuffer.Length); ms.Write(msgCodeBuffer, 0 , msgCodeBuffer.Length); ms.Write(buffer, 0 , msgLen); sendMsgBuffer = ms.ToArray(); } lock (m_SendQueue) { m_SendQueue.Enqueue(sendMsgBuffer); CheckSendBuffer(); } } private void CheckSendBuffer (){ lock (m_SendQueue) { if (m_SendQueue.Count > 0 ) { byte [] buffer = m_SendQueue.Dequeue(); m_Socket.BeginSend(buffer, 0 , buffer.Length, SocketFlags.None, SendCallback, m_Socket); } } } private void SendCallback (IAsyncResult ir ){ m_Socket.EndSend(ir); CheckSendBuffer(); }
这里为了保证线程安全仍然需要把数据入队，在确认到消息成功发送后才进行下一次数据的发送。
下面贴上整个TCP通信框架的代码，直接调用Connect方法进行连接，连接成功后调用Send方法进行发送。
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 using System;using System.Collections;using System.Collections.Generic;using System.IO;using System.Net;using System.Net.Sockets;using System.Security.Policy;using UnityEngine;using UnityEngine.SocialPlatforms;public class SocketMgr : MonoBehaviour { public static SocketMgr Instance = null ; public Action<ushort , byte []> onReceive = null ; public Action OnConnectSuccess = null ; public Action OnConnectFail = null ; public Action OnDisConnect = null ; public bool IsConnected { get { return m_IsConnected; } } private void Awake () { Instance = this ; m_ReceiveBuffer = new byte [1024 * 512 ]; m_SendQueue = new Queue<byte []>(); m_ReceiveQueue = new Queue<byte []>(); m_OnEventCallQueue = new Queue<Action>(); } public void Connect (string ip, int port { m_IP = ip; m_Port = port; m_Socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp); try { m_Socket.Connect(new IPEndPoint(IPAddress.Parse(ip), port)); m_ReceiveStream = new MemoryStream(); m_IsConnected = true ; StartReceive(); if (OnConnectSuccess != null ) { OnConnectSuccess(); } Debug.Log("连接服务器:" + ip + "成功！" ); } catch (Exception e) { if (OnConnectFail != null ) { OnConnectFail(); } Debug.Log(e.Message); } } public void Close () { if (!m_IsConnected) return ; m_IsConnected = false ; try { m_Socket.Shutdown(SocketShutdown.Both); } catch { } m_Socket.Close(); m_SendQueue.Clear(); m_ReceiveQueue.Clear(); m_ReceiveStream.SetLength(0 ); m_ReceiveStream.Close(); m_Socket = null ; m_ReceiveStream = null ; m_OnEventCallQueue.Enqueue(OnDisConnect); } public void Send (ushort msgCode, byte [] buffer { if (!m_IsConnected) return ; byte [] sendMsgBuffer = null ; using (MemoryStream ms = new MemoryStream()) { int msgLen = buffer.Length; byte [] lenBuffer = BitConverter.GetBytes((ushort )msgLen); byte [] msgCodeBuffer = BitConverter.GetBytes(msgCode); ms.Write(lenBuffer, 0 , lenBuffer.Length); ms.Write(msgCodeBuffer, 0 , msgCodeBuffer.Length); ms.Write(buffer, 0 , msgLen); sendMsgBuffer = ms.ToArray(); } lock (m_SendQueue) { m_SendQueue.Enqueue(sendMsgBuffer); CheckSendBuffer(); } } private void Update () { if (m_IsConnected) CheckReceiveBuffer(); if (m_OnEventCallQueue.Count > 0 ) { Action a = m_OnEventCallQueue.Dequeue(); if (a != null ) a(); } } private void StartReceive () { if (!m_IsConnected) return ; m_Socket.BeginReceive(m_ReceiveBuffer, 0 , m_ReceiveBuffer.Length, SocketFlags.None, OnReceive, m_Socket); } private void OnReceive (IAsyncResult ir ) { if (!m_IsConnected) return ; try { int length = m_Socket.EndReceive(ir); if (length < 1 ) { Debug.Log("服务器断开连接" ); Close(); return ; } m_ReceiveStream.Position = m_ReceiveStream.Length; m_ReceiveStream.Write(m_ReceiveBuffer, 0 , length); if (m_ReceiveStream.Length < 4 ) { StartReceive(); return ; } while (true ) { m_ReceiveStream.Position = 0 ; byte [] msgLenBuffer = new byte [2 ]; m_ReceiveStream.Read(msgLenBuffer, 0 , 2 ); int msgLen = BitConverter.ToUInt16(msgLenBuffer, 0 ) + 2 ; int fullLen = 2 + msgLen; if (m_ReceiveStream.Length < fullLen) { break ; } byte [] msgBuffer = new byte [msgLen]; m_ReceiveStream.Position = 2 ; m_ReceiveStream.Read(msgBuffer, 0 , msgLen); lock (m_ReceiveQueue) { m_ReceiveQueue.Enqueue(msgBuffer); } int remainLen = (int )m_ReceiveStream.Length - fullLen; if (remainLen < 1 ) { m_ReceiveStream.Position = 0 ; m_ReceiveStream.SetLength(0 ); break ; } m_ReceiveStream.Position = fullLen; byte [] remainBuffer = new byte [remainLen]; m_ReceiveStream.Read(remainBuffer, 0 , remainLen); m_ReceiveStream.Position = 0 ; m_ReceiveStream.SetLength(0 ); m_ReceiveStream.Write(remainBuffer, 0 , remainLen); remainBuffer = null ; } } catch (Exception e) { Debug.Log("++服务器断开连接," + e.Message); Close(); return ; } StartReceive(); } private void CheckSendBuffer () { lock (m_SendQueue) { if (m_SendQueue.Count > 0 ) { byte [] buffer = m_SendQueue.Dequeue(); m_Socket.BeginSend(buffer, 0 , buffer.Length, SocketFlags.None, SendCallback, m_Socket); } } } private void CheckReceiveBuffer () { while (true ) { if (m_CheckCount > 5 ) { m_CheckCount = 0 ; break ; } m_CheckCount++; lock (m_ReceiveQueue) { if (m_ReceiveQueue.Count < 1 ) { break ; } byte [] buffer = m_ReceiveQueue.Dequeue(); byte [] msgContent = new byte [buffer.Length - 2 ]; ushort msgCode = 0 ; using (MemoryStream ms = new MemoryStream(buffer)) { byte [] msgCodeBuffer = new byte [2 ]; ms.Read(msgCodeBuffer, 0 , msgCodeBuffer.Length); msgCode = BitConverter.ToUInt16(msgCodeBuffer, 0 ); ms.Read(msgContent, 0 , msgContent.Length); } if (onReceive != null ) { onReceive(msgCode, msgContent); } } } } private void SendCallback (IAsyncResult ir ) { m_Socket.EndSend(ir); CheckSendBuffer(); } private void OnDestroy () { Close(); m_SendQueue = null ; m_ReceiveQueue = null ; m_ReceiveStream = null ; m_ReceiveBuffer = null ; m_OnEventCallQueue.Clear(); m_OnEventCallQueue = null ; } private Queue<Action> m_OnEventCallQueue = null ; private Queue<byte []> m_SendQueue = null ; private Queue<byte []> m_ReceiveQueue = null ; private MemoryStream m_ReceiveStream = null ; private byte [] m_ReceiveBuffer = null ; private bool m_IsConnected = false ; private string m_IP = string .Empty; private int m_CheckCount = 0 ; private int m_Port = int .MaxValue; private Socket m_Socket = null ; }
结语 以上就是在Unity中实现TCP通信的全部内容，下一篇就去实现服务端的TCP，把这篇内容真正的跑起来。
