Windows下编译Google.Protobuf在Qt(C++)中使用与Unity3d(C#)交互

1.首先从Github-Protobuf下载代码，本文下载的版本号是3.1.0.

2.仔细查看各个README，有相关的资源下载和编译说明.

3.在一个方便的地方创建一个Install类型的文件夹，放置Cmake生成的工程文件相关内容，使用CMake-gui配置，生成visual studio ide工程.

CMAKE_CONFIGRATION_TYPES是工程配置类型，可以删除不感兴趣的配置.

CMAKE_INSTALL_PREFIX是导出visual studio ide项目文件的位置

根据自己的需求选择BUILD_SHARED_LIBS或者是MSVC_STATIC_RUNTIME(对应编译选项/Mtd和/Mt)，二者选其一

4.Open Project直接编译工程.

---

将生成的protobuf的库引用项目，报如下错误:

 error LNK2001: 无法解析的外部符号 "class google::protobuf::internal::ExplicitlyConstructed<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > > google::protobuf::internal::fixed_address_empty_string" (?fixed_address_empty_string@internal@protobuf@google@@3V?$ExplicitlyConstructed@V?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@@@std@@@@A)
 error LNK2001: 无法解析的外部符号 "class google::protobuf::internal::ExplicitlyConstructed<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > > google::protobuf::internal::fixed_address_empty_string" (?fixed_address_empty_string@internal@protobuf@google@@3V?$ExplicitlyConstructed@V?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@@@std@@@@A)
 error LNK2001: 无法解析的外部符号 "int google::protobuf::internal::empty_string_once_init_" (?empty_string_once_init_@internal@protobuf@google@@3HA)

需要在工程中添加预处理PROTOBUF_USE_DLLS

---

Protos:

 syntax = "proto3";

 message CoinMsg
 {

 }

 syntax = "proto3";

 message ExecMsg
 {
     string name = ;
 }

 syntax = "proto3";

 message VerifyMsg
 {
     bool isOk = ;
     string error = ;
 }

 syntax = "proto3";

 import "ExecMsg.proto";
 import "CoinMsg.proto";
 import "VerifyMsg.proto";

 message MsgPolicy
 {
     enum Type
     {
         ExecMsg = ;
         CoinMsg = ;
         VerifyMsg = ;
     }
     Type type = ;
     ExecMsg execMsg = ;
     CoinMsg coinMsg = ;
     VerifyMsg verifyMsg = ;
 }

　　每个Message对应一个proto文件　　

// 一次生成完cpp与csharp代码，注protobuf-version-3.1.0
protoc -I ./*.proto --cpp_out=../cpp --csharp_out=../csharp

　　

使用示例:

 #include "ConfigHelper.h"
 #include <QFile>
 #include <QDebug>
 #include <QDataStream>
 #include <iostream>
 #include <fstream>
 #include <string>
 #include "MsgPolicy.pb.h"
 #include <google/protobuf/message_lite.h>
 #include <google/protobuf/io/coded_stream.h>
 #include <google/protobuf/io/zero_copy_stream_impl_lite.h>

 ConfigHelper* ConfigHelper::instance = new ConfigHelper();

 ConfigHelper::ConfigHelper()
 {
 #pragma region standard c++ io
     {
         // 序列化到文件
         MsgPolicy msgPolicy;
         ExecMsg* execMsg = new ExecMsg();
         execMsg->set_name("exec message name.");
         msgPolicy.set_allocated_execmsg(execMsg);
         msgPolicy.set_type(MsgPolicy::ExecMsg);
         //QFile file("msg.bin");
         //file.open(QIODevice::WriteOnly);
         std::fstream out("msg.bin", std::ios::out | std::ios::binary | std::ios::trunc);
         msgPolicy.SerializeToOstream(&out);
         out.close();

         // 从文件反序列化到对象
         MsgPolicy dmsgPolicy;
         std::fstream in("msg.bin", std::ios::in | std::ios::binary);
         if (!dmsgPolicy.ParseFromIstream(&in))
         {
             qDebug() << "deserialize data error.";
             return;
         }
         if (dmsgPolicy.type() == MsgPolicy_Type::MsgPolicy_Type_CoinMsg);
         else if (dmsgPolicy.type() == MsgPolicy_Type::MsgPolicy_Type_ExecMsg)
         {
             qDebug() << "policy message type = " << "MsgPolicy_Type::MsgPolicy_Type_ExecMsg";
             qDebug() << "execMsg name = " << QString::fromStdString(dmsgPolicy.execmsg().name());
         }
         else if (dmsgPolicy.type() == MsgPolicy_Type::MsgPolicy_Type_VerifyMsg);
         in.close();
     }
 #pragma endregion standard c++ io

 #pragma region protobuf codedstream
     {
         // 序列化
         MsgPolicy msgPolicy5;
         VerifyMsg* verifyMsg = new VerifyMsg();
         verifyMsg->set_isok(false);
         verifyMsg->set_error("the password is invalid.");
         msgPolicy5.set_allocated_verifymsg(verifyMsg);
         msgPolicy5.set_type(MsgPolicy_Type::MsgPolicy_Type_VerifyMsg);
         int len = msgPolicy5.ByteSize() + ;
         char* buffer = new char[len];
         google::protobuf::io::ArrayOutputStream arrayOut(buffer, len);
         google::protobuf::io::CodedOutputStream codedOut(&arrayOut);
         codedOut.WriteVarint32(msgPolicy5.ByteSize());
         if (!msgPolicy5.SerializeToCodedStream(&codedOut))
         {
             qDebug() << "serialize error.";
         }
         delete buffer;

         // 序列化
         len = msgPolicy5.ByteSize();
         buffer = new char[len];
         if (!msgPolicy5.SerializeToArray(buffer, len)) qDebug() << "serialize error.";

         // 反序列化
         MsgPolicy msgPolicy6;
         msgPolicy6.ParseFromArray(buffer, len);
         if (msgPolicy6.type() == MsgPolicy_Type::MsgPolicy_Type_CoinMsg);
         else if (msgPolicy6.type() == MsgPolicy_Type::MsgPolicy_Type_ExecMsg);
         else if (msgPolicy6.type() == MsgPolicy_Type::MsgPolicy_Type_VerifyMsg)
         {
             qDebug() << "policy message type = " << "MsgPolicy_Type::MsgPolicy_Type_VerifyMsg";
             qDebug() << "isOk = " << msgPolicy6.verifymsg().isok() << "error = " << QString::fromStdString(msgPolicy6.verifymsg().error());
         }
         delete buffer;
     }
 #pragma endregion protobuf codedstream
     google::protobuf::ShutdownProtobufLibrary();
 }

// 输出结果
policy message type =  MsgPolicy_Type::MsgPolicy_Type_ExecMsg
execMsg name =  "exec message name."
policy message type =  MsgPolicy_Type::MsgPolicy_Type_VerifyMsg
isOk =  false error =  "the password is invalid."

下面展示与unity3d 2017.2使用Google.Protobuf的数据通信(Google.Protobuf --Version 3.1.0)

---

1.Qt中关键代码

 udpHelper = new UDPHelper(this, , );
     QUdpSocket *udp = udpHelper->UdpSocket();
     connect(udp, &QUdpSocket::readyRead, this, [=]() {
         while (udp->hasPendingDatagrams())
         {
             QNetworkDatagram dg = udp->receiveDatagram();
             QByteArray dga = dg.data();
             QString str(dga);

             MsgPolicy msg;
             msg.ParseFromString(str.toStdString());
             if (msg.type() == MsgPolicy_Type::MsgPolicy_Type_CoinMsg);
             else if (msg.type() == MsgPolicy_Type::MsgPolicy_Type_ExecMsg);
             else if (msg.type() == MsgPolicy_Type::MsgPolicy_Type_VerifyMsg)
             {
                 qDebug() << "policy message type = " << "MsgPolicy_Type::MsgPolicy_Type_VerifyMsg";
                 qDebug() << "isOk = " << msg.verifymsg().isok() << "error = " << QString::fromStdString(msg.verifymsg().error());
             }
         }
     });

 MsgPolicy msg;
         VerifyMsg *verify = new VerifyMsg();
         verify->set_isok(true);
         verify->set_error("from qt c++.");
         msg.set_allocated_verifymsg(verify);
         msg.set_type(MsgPolicy_Type::MsgPolicy_Type_VerifyMsg);
         // 序列化
         int len = msg.ByteSize();
         char *buffer = new char[len];
         if (!msg.SerializeToArray(buffer, len)) qDebug() << "serialize error.";
         else udpHelper->Write(buffer, len);

2.Unity3d中关键代码

 using System;
 using System.Collections;
 using System.Collections.Generic;
 using System.Net;
 using System.Net.Sockets;
 using System.Text;
 using System.Threading.Tasks;
 using Google.Protobuf;
 using UnityEngine;

 public class UdpHelper: IDisposable
 {
     private UdpClient udp;
     private IPEndPoint remote;
     public Action<byte[]> onData;

     public async Task Setup(int src, int dst)
     {
         remote = new IPEndPoint(IPAddress.Parse("127.0.0.1"), dst);
         //udp = new UdpClient(src);
         udp = new UdpClient(new IPEndPoint(IPAddress.Parse("127.0.0.1"), src));
         #region Windows udp 10054 error（ConnectionReset[远程主机强迫关闭一个现有连接]）
         // 问题详情: https://www.cnblogs.com/pasoraku/p/5612105.html
         uint IOC_IN = 0x80000000;
         int IOC_VENDOR = 0x18000000;
 #pragma warning disable CS0675 // 对进行了带符号扩展的操作数使用了按位或运算符
         int SIO_UDP_CONNRESET = (int)(IOC_IN | IOC_VENDOR | );
 #pragma warning restore CS0675 // 对进行了带符号扩展的操作数使用了按位或运算符
         udp.Client.IOControl(SIO_UDP_CONNRESET, new[] { Convert.ToByte(false) }, null);
         #endregion

         await Listener();
     }

     private async Task Listener()
     {
         try
         {
             UdpReceiveResult result = await udp.ReceiveAsync();
             if (onData != null)
                 onData.Invoke(result.Buffer);
             await Listener();
         }
         catch (ObjectDisposedException) { } // Ignore
         catch (Exception e)
         {
             Debug.LogWarning(e.Message);
         }
     }

     public void Send(byte[] data)
     {
         if (udp != null)
         {
             udp.SendAsync(data, data.Length, remote);
         }
     }

     public void Dispose()
     {
         if (udp != null)
         {
             udp.Close();
             udp = null;
         }
     }
 }

 udpHelper = new UdpHelper();
 udpHelper.onData += bytes =>
 {
     MsgPolicy msg = MsgPolicy.Parser.ParseFrom(bytes);
     if (msg.Type == MsgPolicy.Types.Type.CoinMsg) ;
     else if (msg.Type == MsgPolicy.Types.Type.ExecMsg) ;
     else if (msg.Type == MsgPolicy.Types.Type.VerifyMsg)
     {
         Debug.LogWarning("policy message type = " + "MsgPolicy_Type::MsgPolicy_Type_VerifyMsg");
         Debug.LogWarning("isOk = " + msg.VerifyMsg.IsOk + " error = " + msg.VerifyMsg.Error);
     }
 };
 await udpHelper.Setup(srcUdpPort, dstUdpPort);

 MsgPolicy msg = new MsgPolicy();
 msg.Type = MsgPolicy.Types.Type.VerifyMsg;
 msg.VerifyMsg = new VerifyMsg(){IsOk = true, Error = "from unity3d c#"};
 byte[] data = msg.ToByteArray();
 udpHelper.Send(data);

3.程序输出

// In Qt
policy message type =  MsgPolicy_Type::MsgPolicy_Type_VerifyMsg
isOk =  true error =  "from unity3d c#"
// In Unity3d
policy message type = MsgPolicy_Type::MsgPolicy_Type_VerifyMsg
isOk = True error = from qt c++.

　　

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