C# api 动态加载Ｃ＋＋的ＤＬＬ函数方法

Ｃ＋＋函数如下：

// testdll3.cpp : Defines the entry point for the DLL application.
//

#include "stdafx.h"

BOOL APIENTRY DllMain( HANDLE hModule,
                       DWORD ul_reason_for_call,
                       LPVOID lpReserved
      )
{
    return TRUE;
}

extern "C" __declspec(dllexport) int add(int * a,int * b)
{
return *a + *b;
}

Ｃ＃中动态加载方法：

首先写一个加载ＤＬＬ文件的类：

 

class LoadDllAPI      
   {      
            
       [DllImport("kernel32.dll")]      
       public extern static IntPtr LoadLibrary(string path);      
      
       [DllImport("kernel32.dll")]      
       public extern static IntPtr GetProcAddress(IntPtr lib, string funcName);      
      
       [DllImport("kernel32.dll")]      
       public extern static bool FreeLibrary(IntPtr lib);      
      
       [DllImport("kernel32.dll")]      
       public static extern IntPtr GetStdHandle(int nStdHandle);      
      
       [DllImport("user32", EntryPoint = "CallWindowProc")]      
       public static extern int CallWindowProc(IntPtr lpPrevWndFunc, int hwnd, int MSG, int wParam, int lParam);      
   }     
   #endregion      
      
   public class LoadDll      
   {      
       IntPtr DllLib;//DLL文件名柄     
       #region 构造函数      
       public LoadDll()      
       { }      
       public LoadDll(string dllpath)      
       {      
           DllLib = LoadDllAPI.LoadLibrary(dllpath);      
       }     
       #endregion      
       /// <summary>      
       /// 析构函数      
       /// </summary>      
       ~LoadDll()      
       {      
           LoadDllAPI.FreeLibrary(DllLib);//释放名柄      
       }      
       public void initPath(string dllpath)      
       {      
           if (DllLib == IntPtr.Zero)      
           {      
               DllLib = LoadDllAPI.LoadLibrary(dllpath);      
           }      
       }      
       /// <summary>      
       /// 获取ＤＬＬ中一个方法的委托      
       /// </summary>      
       /// <param name="methodname"></param>      
       /// <param name="methodtype"></param>      
       /// <returns></returns>      
       public Delegate InvokeMethod(string methodname, Type methodtype)      
       {      
           IntPtr MethodPtr = LoadDllAPI.GetProcAddress(DllLib, methodname);      
                
           return (Delegate)Marshal.GetDelegateForFunctionPointer(MethodPtr, methodtype);      
       }      
   }     

 

 

*  loadDLL.LoadDll loaddll = new loadDLL.LoadDll();／／实例化加载ＤＬＬ文件的类，，如上      
*         public delegate int delegateadd(IntPtr a,IntPtr b);／／声明此方法的一个委托      
        
 ／／一个调用用的按钮      
        private void button1_Click(object sender, EventArgs e)      
         {      
             loaddll.initPath("testdll3.dll");／／载入文件      
             delegateadd m = (delegateadd)loaddll.InvokeMethod("add", typeof(add));／／获取其中方法的委托      
              int a=1;int b=2;      
       
             int re = m(out a, out b);//得到ＲＥ＝3，，成功      
         }     

 

 

以上方法编译．

调用：