C#通過相對路徑調用C++的dll

最新推荐文章于 2023-06-11 23:06:30 发布

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#c++ #c# #string #api #dll #path

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本文介绍了一种在C#中动态加载DLL文件并调用其内部函数的方法。通过使用[DllImport]属性导入kernel32.dll中的LoadLibrary、GetProcAddress和FreeLibrary函数，可以实现对DLL的加载、函数获取和释放。此外，还提供了一个具体的示例，展示了如何定义委托来调用DLL中的特定函数。

首先我们用[DllImport("kernel32.dll")]private extern static IntPtr LoadLibrary(String path);[DllImport("kernel32.dll")]private extern static IntPtr GetProcAddress(IntPtr lib, String funcName);[DllImport("kernel32.dll")]private extern static bool FreeLibrary(IntPtr lib);分别取得了LoadLibrary和GetProcAddress函数的地址，再通过这两个函数来取得我们的DLL里面的函数。我们可以先用Server.MapPath(@"~/Bin/Judge.dll")来取得我们的DLL的物理路径，然后再用LoadLibrary进行载入，最后用GetProcAddress取得要用的函数地址以下自定义类的代码完成LoadLibrary的装载和函数调用：

public class DllInvoke {

[DllImport("kernel32.dll")]

private extern static IntPtr LoadLibrary(String path);

[DllImport("kernel32.dll")]

private extern static IntPtr GetProcAddress(IntPtr lib, String funcName);

[DllImport("kernel32.dll")]

private extern static bool FreeLibrary(IntPtr lib);

private IntPtr hLib;

public DllInvoke(String DLLPath)

{

hLib = LoadLibrary(DLLPath);

}

~DllInvoke()

{

FreeLibrary(hLib);

}

//将要执行的函数转换为委托

public Delegate Invoke(String APIName,Type t)

{

IntPtr api = GetProcAddress(hLib, APIName);

return (Delegate)Marshal.GetDelegateForFunctionPointer(api,t);

}

我自己使用的代碼：

        [DllImport("kernel32.dll")]
        private extern static IntPtr LoadLibrary(String path);
        [DllImport("kernel32.dll")]
        private extern static IntPtr GetProcAddress(IntPtr lib, String funcName);
        [DllImport("kernel32.dll")]
        private extern static bool FreeLibrary(IntPtr lib);

public delegate int GetFileId([MarshalAs(UnmanagedType.LPTStr)] StringBuilder fileName, [MarshalAs(UnmanagedType.LPTStr)] StringBuilder certSubjectName);

        public static bool invokeDLL(string filename)
        {
            IntPtr hLib;
            string dllPath = System.IO.Path.Combine(System.Windows.Forms.Application.StartupPath, "GetFileId.dll");
            hLib = LoadLibrary(dllPath);

            IntPtr api = GetProcAddress(hLib, "GetFileId");
            GetFileId getFileId = (GetFileId)Marshal.GetDelegateForFunctionPointer(api, typeof(GetFileId));
            long fileId = getFileId(new StringBuilder(filename), new StringBuilder(FTPNET.certValidator.CertName));

FreeLibrary(hLib);

}