C#动态调用非托管dll(转)

尝试着在C#下调用以前Delphi写的一些DLL,基本实现动态调用,传入回调函数,及调用带结构数组指针作为参数的函数.

     虽然DllImport可以方便的静态调用DLL的函数,但在.net2.0中新增加了一个Marshal.GetDelegateForFunctionPointer 方法,可以将非托管函数指针转换为委托。 有了这个方法就可以用三个Windows API函数即：Loadlibrary，GetProcAddress和Freelibrary来实现动态调用DLL了.下面是实现DLL动态调用的静态类

using System;

using System.Collections.Generic;

using System.Text;

using System.Runtime.InteropServices;

using System.Data;

namespace Test

{

    /// <summary>

    /// DLL加载类

    /// </summary>

    internal class DynamicLoadDll

    {

        [DllImport("Kernel32")]

        public static extern int GetProcAddress(int handle, String funcname);

        [DllImport("Kernel32")]

        public static extern int LoadLibrary(String funcname);

        [DllImport("Kernel32")]

        public static extern int FreeLibrary(int handle);

        public static Delegate GetAddress(int dllModule, string functionname, Type t)

        {

            int addr = GetProcAddress(dllModule, functionname);

            if (addr == 0)

                return null;

            else

                return Marshal.GetDelegateForFunctionPointer(new IntPtr(addr), t);

        }

}

Public class referDll

{

private int m_hDLL = 0; //DLL句柄
  private delegate int ShowForm(IntPtr aHandle);
  private ShowForm m_ShowForm;
  private const string DLLNAEM = "XXX.dll";

  m_hDLL = DllLoader.LoadLibrary(DLLNAEM);
  if (m_hDLL == 0)
    { MessageBox.Show("加载失败!")
       return;
    }
 m_ShowForm = (ShowForm) DllLoader.GetAddress(m_hPacsview, "ShowForm", typeof (ShowForm));
//使用ShowForm
 if (m_ShowForm != null)
                m_ShowForm(iHandle);
//卸载DLL
DllLoader.FreeLibrary(m_hDLL);

}

}

接着说说如何调用DLL中带结构数组指针作为参数的函数.在原来Delphi中定义如下:

//一个结构定义如下
TStudyRec  = Record
       UID  : Array[0..127] of Char;
  end;

TCharArray=Array[0..49] of TStudyRec;

//在DLL中有如下函数 其中AStudys为TCharArray的指针
 function Open(AStudys: Pointer): HRESULT; StdCall;

要在C#里正常调用,首先要定义出一个相同的结构

private struct StudyRec
{
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst=128)] public string UID; //名称  
}

接着声明一个委托
private delegate int Open(IntPtr aStudys);
从DLL得到委托实例

private Open m_Open = (Open) DllLoader.GetAddress(m_hDLL, "Open", typeof (Open)); //m_hDLL为DLL指针

到此为止终于在C#里定义出相同的结果及函数了,下面就是要调用了,因为结构数组是要给非托管的DLL使用的,因此最关键的一点是要用Marshal.AllocHGlobal来分配好非托管内存,把结构数组放到内存中去,再把内存指针当作参数调用就OK啦

StudyRec[] arrStudyRec = new StudyRec[50];
  int isize = Marshal.SizeOf(typeof (StudyRec));
  IntPtr parrStudyRec = Marshal.AllocHGlobal(Marshal.SizeOf(isize*50));
  int run = (int) parrStudyRec;

 for (int i = 0; i < 50; i++)
{

arrStudyRec[i].UID =  i.tostring();//这里只是模拟,所以直接把i当作UID了
Marshal.StructureToPtr(arrStudyRec[i], (IntPtr) run, false);
run += isize;

}

 m_Open(parrStudyRec);

转自：http://zhouweigang01.blog.163.com/blog/static/934090720095493459311/