Unreal Engine 4：如何使用动态库和静态库

不念不忘少年蓝@ 2022-04-14 06:10 253阅读 0赞

在开发中经常要用到第三方库，下面将使用第三方库的方法总结一下。

### 一、动态库的添加 ###

UnrealEngine的wiki中提供了一种方案：  
Linking Dlls：https://wiki.unrealengine.com/Linking\_Dlls

dll中的代码：  
https://github.com/XenoEgger/CreateAndLinkDLLTutSol/blob/master/CreateAndLinkDLLTut/CreateAndLinkDLLFile.h  
https://github.com/XenoEgger/CreateAndLinkDLLTutSol/blob/master/CreateAndLinkDLLTut/CreateAndLinkDLLFile.cpp

调用dll的代码：  
https://github.com/XenoEgger/CreateAndLinkDLLProj/blob/master/Source/CreateAndLinkDLLProj/Public/CreateAndLinkDLLTutBFL.h  
https://github.com/XenoEgger/CreateAndLinkDLLProj/blob/master/Source/CreateAndLinkDLLProj/Private/CreateAndLinkDLLTutBFL.cpp

上述方案主要是使用如下两个函数，先获取dll文件句柄，再通过dll句柄获取方法指针，最后通过获取的方法指针调用dll中的方法：

> FPlatformProcess::GetDllHandle(dllFilePath);  
> FPlatformProcess::GetDllExport(dllHandle, procName);

如果只需要调用dll的方法的话，采用上述方案是没有问题的，但如果调用dll中的类的话，上述方案就不合适了。下面就来说说如何调用dll中的类：

比如，将crypto++7和log4cplus-2.0.2编译成dll后生成如下文件：

> crypto++7.lib  
> crypto++7.dll  
> log4cplus-2.0.2.lib  
> log4cplus-2.0.2.dll

crypto++7.lib和log4cplus-2.0.2.lib分别为crypto++7和log4cplus-2.0.2的导出库。

将它们放入工程目录下/Plugins/ThirdParty/Debug中，在\*.Build.cs文件中添加如下代码：

Definitions.AddRange(new string[] {"CRYPTOPP_IMPORTS", "LOG4CPLUS_BUILD_DLL" });
    
    // 第三方库debug目录
    string ThirdPartyPath = Path.Combine(PluginsPath, "ThirdParty/Debug");
    PublicLibraryPaths.Add(ThirdPartyPath);
    
    // 添加.lib文件
    PublicAdditionalLibraries.Add("crypto++7.lib");
    PublicAdditionalLibraries.Add("log4cplus-2.0.2.lib");
    
    PublicIncludePaths.AddRange(new string[] {
        Path.Combine(PluginsPath, "cryptopp-CRYPTOPP_7_0_0/include"),
        Path.Combine(PluginsPath, "log4cplus-2.0.2/include"),
    });

其中，CRYPTOPP\_IMPORTS和LOG4CPLUS\_BUILD\_DLL分别为crypto++7和log4cplus-2.0.2的导入参数；PublicAdditionalLibraries中分别添加了crypto++7和log4cplus-2.0.2的导出库.lib文件；PublicIncludePaths分别添加了crypto++7和log4cplus-2.0.2的头文件路径。

同时crypto++7.dll和log4cplus-2.0.2.dll必须放到Binaries/Win64目录下。

### 二、静态库的添加 ###

方式跟动态库类似，比如，将asio-1.11.0和msgpack-c-cpp-3.1.1编译成静态库后生成如下文件：

> asio-1.11.0.lib  
> msgpack-c-cpp-3.1.1.lib

asio-1.11.0.lib和msgpack-c-cpp-3.1.1.lib都是静态库，不是导出库。

将它们放入工程目录下/Plugins/ThirdParty/Debug中，在\*.Build.cs文件中添加如下代码：

Definitions.AddRange(new string[] { "ASIO_STANDALONE", "MSGPACK_USE_CPP03" });
    
    // 第三方库debug目录
    string ThirdPartyPath = Path.Combine(PluginsPath, "ThirdParty/Debug");
    PublicLibraryPaths.Add(ThirdPartyPath);
    
    // 添加.lib文件
    PublicAdditionalLibraries.Add("asio-1.11.0.lib");
    PublicAdditionalLibraries.Add("msgpack-c-cpp-3.1.1.lib");
    
    PublicIncludePaths.AddRange(new string[] {
    	Path.Combine(PluginsPath, "asio-1.11.0/include"),
    	Path.Combine(PluginsPath, "msgpack-c-cpp-3.1.1/include"),
    });

其中，ASIO\_STANDALONE和MSGPACK\_USE\_CPP03分别为asio-1.11.0和msgpack-c-cpp-3.1.1在编译时要用到的参数；PublicAdditionalLibraries中分别添加了asio-1.11.0和msgpack-c-cpp-3.1.1的静态库.lib文件；PublicIncludePaths分别添加了asio-1.11.0和msgpack-c-cpp-3.1.1的头文件路径。

参考文档：

[Linking Dlls][]  
[Linking Static Libraries Using The Build System][]  
[How to Link External C Libraries .dll .lib With Your Project & Package With Game, Fast And Easy][How to Link External C Libraries .dll .lib With Your Project _ Package With Game_ Fast And Easy]

[Linking Dlls]: https://wiki.unrealengine.com/Linking_Dlls
[Linking Static Libraries Using The Build System]: https://wiki.unrealengine.com/Linking_Static_Libraries_Using_The_Build_System
[How to Link External C Libraries .dll .lib With Your Project _ Package With Game_ Fast And Easy]: https://wiki.unrealengine.com/How_to_Link_External_C_Libraries_.dll_.lib_With_Your_Project_%26_Package_With_Game,_Fast_And_Easy