首先感谢一下官方论坛的9KGameStudio 以及A先生，没有你们就没有此文。
9KGameStudio的Mysql教程地址：https://forums.unrealengine.com/showthread.php?65944-c-Mysql-database-error&highlight=mysql
写在教程之前：
Ue4使用Module这个东西来管理第三方的库，（包括你的工程）。我认为这个机制是Ue4程序员必须掌握的东西，不然你在扩展UE4库的路上将会寸步难行。
此文是9KGameStudio的Mysql教程的中文重写版，里面会写入一些个人体会，当然本人也是个UE4 C++菜鸟，有错的地方还请见谅。
教程开始：
一、建立你自己的mysqlModule。
1、在你的项目文件夹下建立一个名为ThirdParty的文件夹
MyProject
Binaries
Build
Config
Content
Intermediate
Saved
Source
ThirdParty
MyProject.sln
MyProject.uproject
2、之后将Mysql连接文件放入这个文件夹，本教程中用的是 MySQL Connector.C6.1。
ThirdParty
MySQL Connector.C 6.1
include
lib
3、将MySQL Connector.C6.1文件夹中的空格去掉，改成MySQLConnector.C6.1。
4、按照一下结构建立目录：
Source（你工程中的Source目录）
MyProject (Source目录下的，你的CPP,H文件放置目录)
MySQLSupport (在Source下新建文件夹，并且命名MySQLSupport，注意大小写！)
Public（在MySQLSupport目录下新建文件夹）
MySQLSupport.h（在Public目录下，使用记事本文件新建再改名）
Private（在MySQLSupport目录下新建文件夹）
MySQLSupport.cpp（在Private目录下，使用记事本文件新建再改名）
MySQLSupportPrivatePCH.h（在Private目录下，使用记事本文件新建改名）
MySQLSupport.Build.cs（在MySQLSupport目录下，使用记事本文件新建再改名）
5、为新建的文件编写代码：
MySQLSupport.h
#pragma once
#include "ModuleManager.h"
class IMySQLSupport : publicIModuleInterface
{
public:
staticinline IMySQLSupport& Get()
{
returnFModuleManager::LoadModuleChecked<IMySQLSupport>("MySQLSupport");
}
staticinline bool IsAvailable()
{
returnFModuleManager::Get().IsModuleLoaded("MySQLSupport");
}
};
MySQLSupport.cpp
#include "MySQLSupportPrivatePCH.h"
#include "MySQLSupport.h"
class FMySQLSupport : public IMySQLSupport
{
virtual void StartupModule() override;
virtual void ShutdownModule() override;
};
IMPLEMENT_MODULE(FMySQLSupport, MySQLSupport)
void FMySQLSupport::StartupModule()
{
}
void FMySQLSupport::ShutdownModule()
{
}
MySQLSupportPrivatePCH.h
#pragma once
#include "Engine.h"
MySQLSupport.Build.cs
using UnrealBuildTool;
using System.IO;
public class MySQLSupport : ModuleRules
{
public MySQLSupport(TargetInfo Target)
{
PublicDependencyModuleNames.AddRange(
new string[] {
"Core",
"CoreUObject",
"Engine"
});
string ModulePath = Path.GetDirectoryName(RulesCompiler.GetModuleFilename(this.GetType().Name)); // gets the directory path of this module
string ThirdPartyPath = Path.GetFullPath(Path.Combine(ModulePath, "../../ThirdParty/")); // gets the ThirdParty folder directory path
string MySQLConnectorPath = ThirdPartyPath + "
MySQL
Connector.C 6.1
/"; // gets the
MySQL
Connector.C 6.1 folder path
string MySQLConnectorLibraryPath = MySQLConnectorPath + "lib/"; // gets the path of the lib folder
string MySQLConnectorIncludePath = MySQLConnectorPath + "include/"; // gets the path of the include folder
string MySQLConnectorImportLibraryName = Path.Combine(MySQLConnectorLibraryPath, "libmysql.lib"); // gets the file path and name of the libmysql.lib static import library
string MySQLConnectorDLLName = Path.Combine(MySQLConnectorLibraryPath, "libmysql.dll"); // gets the file path and name of libmysql.dll
if (!File.Exists(MySQLConnectorImportLibraryName)) // check to ensure the static import lib can be located, or else we'll be in trouble
{
throw new BuildException(string.Format("{0} could not be found.", MySQLConnectorImportLibraryName)); // log an error message explaining what went wrong if not found
}
if (!File.Exists(MySQLConnectorDLLName)) // check to make sure the dll can be located or else we'll be in trouble
{
throw new BuildException(string.Format("{0} could not be found.", MySQLConnectorDLLName)); // log an error message explaining what went wrong if not found
}
PrivateIncludePaths.Add(MySQLConnectorIncludePath); // add the "include" folder to our dependencies. I've chosen PrivateIncludePaths since I hide the
mysql
headers from external code
PublicLibraryPaths.Add(MySQLConnectorLibraryPath); // add the "lib" folder to our dependencies
PublicAdditionalLibraries.Add(MySQLConnectorImportLibraryName); // add libmysql.lib static import library as a dependency
PublicDelayLoadDLLs.Add(MySQLConnectorDLLName); // add libmysql.dll as a dll
}
}
6、到你的项目中的2个CS文件中加入OutExtraModuleNames.AddRange(new string[]{ "MySQLSupport" });
MyProject.Target.cs
MyProjectEditor.Target.cs
这里有一个百思不得其解的地方，A先生的项目需要经过这一步才能正常编译。本人家中电脑不加也可以正常编译。
注意：你需要把MySQLConnector.C 6.1 中的空格去掉
二、包含Mysql连接文件
在你的项目上右键-属性-VC++目录-包含目录与库目录中填入，刚才建立的ThirdParty中的连接文件中include与lib目录。
包含目录：对应include
C:\Users\creaform\Documents\Unreal Projects\ThirdPerson\ThirdParty\MySQLConnector.C6.1\include;$(IncludePath)库目录：对应lib
C:\Users\creaform\Documents\Unreal Projects\ThirdPerson\ThirdParty\MySQLConnector.C6.1\lib;$(LibraryPath)三、使用代码连接Mysql
这里你贴一段A先生的代码。他是把代码写在GameMode中的
MyGameMode.h
#pragmaonce
#include"GameFramework/GameMode.h"
#include"MyGameMode.generated.h"
/**
*
*/
UCLASS()
classFSGAME_API AMyGameMode : public AGameMode
{
GENERATED_UCLASS_BODY()
virtual void BeginPlay() OVERRIDE;
};
MyGameMode.cpp
#include"FSGame.h"
#include"MyGameMode.h"
#include"MyCharacter.h"
#include"MySQLSupport/Public/MySQLSupport.h"
#include"AllowWindowsPlatformTypes.h"
#include<winsock2.h>
#include<mysql.h>
#include"HideWindowsPlatformTypes.h"
#pragmacomment(lib, "libmysql.lib")
AMyGameMode::AMyGameMode(constFObjectInitializer& ObjectInitializer)
: Super(ObjectInitializer)
{
DefaultPawnClass = AMyCharacter::StaticClass();
static ConstructorHelpers::FClassFinder<APawn>PlayerPawnObject(TEXT("/Game/StarterContent/Character/MyChatacter_Blueprint"));
if (PlayerPawnObject.Class != NULL){
DefaultPawnClass = PlayerPawnObject.Class;
}
}
voidAMyGameMode::BeginPlay()
{
if (GEngine) {
MYSQL* conn;
conn = mysql_init(NULL);
mysql_real_connect(conn, "127.0.0.1","root", "123456", "test", 3306, NULL, 0);
int32 version = mysql_get_server_version(conn);
mysql_close(conn);
FString version_str;
version_str = FString::FormatAsNumber(version);
GEngine->AddOnScreenDebugMessage(-1, 10.f,FColor(255, 0, 0), TEXT("正在使用MyGameMode"));
GEngine->AddOnScreenDebugMessage(-1, 10.f,FColor(255, 0, 0), FString(TEXT("当前正在使用的mysql版本为"))+version_str);
}
}
当然代码不能照搬照抄，你需要求改修改代码中的函数名，等一些东西，因为用到GEngine，所以需要到你的项目头文件中把#include"EngineMinimal.h"改成#include "Engine.h"
#include<winsock2.h>
#include<mysql.h>这两个头文件用于mysql的依赖项
#include"AllowWindowsPlatformTypes.h"
#include"HideWindowsPlatformTypes.h"这两个头文件使得MFC的一些变量可以正常使用。
PS：关于使用第三方库的另一盘文章（中文）https://wiki.unrealengine.com/UE4与WEB服务器交互(json)
我使用虚拟机测试过可以远程连接Mysql数据库，当然之前需要设置一下让Mysql允许别的Ip连接。
我是使用MySQL Workbench 6.3 CE，登陆数据库，之后在Users and Privileges 选项中把用户的IP改成%。
本人家中电脑已经成功2次了，但是另一台电脑却总是编译失败。不知道为什么？
编译的错误：
错误 7 error : Failed to produce item:C:\Users\creaform\Documents\UnrealProjects\ThirdPerson\Binaries\Win64\UE4Editor-ThirdPerson.dll C:\Users\creaform\Documents\UnrealProjects\ThirdPerson\Intermediate\ProjectFiles\ERROR ThirdPerson
错误 6 error LNK1120: 4 个无法解析的外部命令 C:\Users\creaform\Documents\UnrealProjects\ThirdPerson\Binaries\Win64\UE4Editor-ThirdPerson.dll ThirdPerson
错误 5 error LNK2019: 无法解析的外部符号 mysql_close，该符号在函数 "public: virtual void __cdeclAThirdPersonGameMode::BeginPlay(void)" (?BeginPlay@AThirdPersonGameMode@@UEAAXXZ)中被引用 C:\Users\creaform\Documents\UnrealProjects\ThirdPerson\Intermediate\ProjectFiles\ThirdPersonGameMode.cpp.obj ThirdPerson
错误 4 error LNK2019: 无法解析的外部符号mysql_get_server_version，该符号在函数 "public: virtual void __cdeclAThirdPersonGameMode::BeginPlay(void)"(?BeginPlay@AThirdPersonGameMode@@UEAAXXZ) 中被引用 C:\Users\creaform\Documents\UnrealProjects\ThirdPerson\Intermediate\ProjectFiles\ThirdPersonGameMode.cpp.obj ThirdPerson
错误 2 error LNK2019: 无法解析的外部符号 mysql_init，该符号在函数 "public: virtual void __cdeclAThirdPersonGameMode::BeginPlay(void)"(?BeginPlay@AThirdPersonGameMode@@UEAAXXZ) 中被引用 C:\Users\creaform\Documents\UnrealProjects\ThirdPerson\Intermediate\ProjectFiles\ThirdPersonGameMode.cpp.obj ThirdPerson
错误 3 error LNK2019: 无法解析的外部符号mysql_real_connect，该符号在函数 "public: virtual void __cdeclAThirdPersonGameMode::BeginPlay(void)"(?BeginPlay@AThirdPersonGameMode@@UEAAXXZ) 中被引用 C:\Users\creaform\Documents\UnrealProjects\ThirdPerson\Intermediate\ProjectFiles\ThirdPersonGameMode.cpp.obj ThirdPerson
错误 8 error MSB3073: 命令“D:\unreal4\UnrealEngine-release\UnrealEngine-release\Engine\Build\BatchFiles\Build.batThirdPersonEditor Win64 Development "C:\Users\creaform\Documents\UnrealProjects\ThirdPerson\ThirdPerson.uproject"”已退出，代码为 -1。 C:\Program Files(x86)\MSBuild\Microsoft.Cpp\v4.0\V120\Microsoft.MakeFile.Targets 38 5 ThirdPerson
警告 1 未能找到引用的组件“RPCUtility”。 iPhonePackager
