UE（虚幻）学习（三） UnrealSharp插件中调用非托管DLL

上一篇文章中我使用UnrealSharp成功使用了我的一个C#控制台程序中的网络模块，这个程序是基于KCP网络了，其中调用了Cmake 编译的一个C++的DLL，在虚幻中DLL需要放在Binaries目录中才可以。Unity中只要放在任意Plugins目录中就可以。
但是Binaries目录版本控制一般不提交，我们可以改一下，改成按照路径加载。

修改前的脚本

using System.Runtime.InteropServices;//脚本修改自//https://github.com/a11s/kcp_warppernamespace NetLibrary
{public unsafe class KCP{const string LIBNAME = "libikcp.dll";//---------------------------------------------------------------------// interface//---------------------------------------------------------------------/// <summary>/// create a new kcp control object, 'conv' must equal in two endpoint/// from the same connection. 'user' will be passed to the output callback/// output callback can be setup like this: 'kcp->output = my_udp_output'/// </summary>/// <param name="conv"></param>/// <param name="user"></param>/// <returns></returns>[DllImport(LIBNAME, EntryPoint = "ikcp_create", CallingConvention = CallingConvention.Cdecl)]public static extern IKCPCB* ikcp_create(uint conv, void* user);/// <summary>/// release kcp control object/// </summary>/// <param name="kcp"></param>[DllImport(LIBNAME, EntryPoint = "ikcp_release", CallingConvention = CallingConvention.Cdecl)]public static extern void ikcp_release(IKCPCB* kcp);/// <summary>/// set output callback, which will be invoked by kcp///public static extern void ikcp_setoutput(IKCPCB* kcp, int (* output)(byte* buf, int len,             ikcpcb *kcp, void* user));/// </summary>/// <param name="kcp"></param>/// <param name="d_output"></param>[DllImport(LIBNAME, EntryPoint = "ikcp_setoutput", CallingConvention = CallingConvention.Cdecl)]public static extern void ikcp_setoutput(IKCPCB* kcp, System.IntPtr d_output);

篇幅太大没有必要，只展示部分代码片段。
可以看到之前是通过DllImport 载入LIBNAME变量来载入DLL的。

改为动态路径

先放上所有改动

// 动态获取库路径
private static string GetLibraryPath()
{string baseDirectory = AppDomain.CurrentDomain.BaseDirectory;//动态库的路径被拼接到 Binaries\Managed\Third\libikcp.dll，而你的实际库文件存放在 E:\myproject\Third\libikcp.dll，这说明 AppDomain.CurrentDomain.BaseDirectory 返回的路径是 Binaries\Managed。baseDirectory = Path.Combine(baseDirectory, "../../");string relativePath;// 根据平台选择库路径if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows)){relativePath = "ThirdParty/Kcp/Win64/libikcp.dll";}else if (RuntimeInformation.IsOSPlatform(OSPlatform.Create("ANDROID"))){relativePath = "ThirdParty/Kcp/Android/arm64-v8a/libikcp.so";}else{throw new PlatformNotSupportedException("Unsupported platform");}return Path.Combine(baseDirectory, relativePath);
}// DllImport 使用动态路径
private const string LIBNAME = "PLACEHOLDER"; // 占位符
private static bool _isResolverSet = false;
// 添加初始化方法以动态设置路径
public static void Initialize()
{if (_isResolverSet){Loger.Debug($"BSserver DLL: 已经加载过了 .");return;}try{string libraryPath = GetLibraryPath();//Loger.Error($"BSserver DLL:{libraryPath}");NativeLibrary.SetDllImportResolver(typeof(KCP).Assembly, (name, assembly, path) =>{if (name == LIBNAME){return NativeLibrary.Load(libraryPath);}return IntPtr.Zero;});_isResolverSet = true;}catch(Exception e) {//AClientMain.inst.PrintString("C# : DLL:" + libraryPath);Console.WriteLine($"Loaded library 加载错误 ."+e.Message);Loger.Error($"BSserver DLL 加载错误 : " + e.Message);}}
//const string LIBNAME = "libikcp.dll";
//---------------------------------------------------------------------
// interface
//---------------------------------------------------------------------/// <summary>
/// create a new kcp control object, 'conv' must equal in two endpoint
/// from the same connection. 'user' will be passed to the output callback
/// output callback can be setup like this: 'kcp->output = my_udp_output'
/// </summary>
/// <param name="conv"></param>
/// <param name="user"></param>
/// <returns></returns>
[DllImport(LIBNAME, EntryPoint = "ikcp_create", CallingConvention = CallingConvention.Cdecl)]
public static extern IKCPCB* ikcp_create(uint conv, void* user);/// <summary>
/// release kcp control object
/// </summary>
/// <param name="kcp"></param>
[DllImport(LIBNAME, EntryPoint = "ikcp_release", CallingConvention = CallingConvention.Cdecl)]
public static extern void ikcp_release(IKCPCB* kcp);

使用方法：
我们在UE的工程下创建目录ThirdParty，按照代码里的路径，把DLL放进去，按照不同平台。

在加载DLL之前，我们需要调用Initialize方法初始化动态设置路径就可以了。

这些代码是ChatGPT帮忙写的，经过几次修改有了这段代码。

小技巧

以前是内事不决问baidu，外事不决问google，现在是内事问豆包，外事问ChatGPT。 ：）
但是小心AI一本正经的胡说八道。 ：P