DLLimport 虚拟路径用法

1.创建类库应用帮助类DLLWrapper

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Runtime.InteropServices;

/// <summary>
/// Summary description for Class1
/// </summary>
public class DLLWrapper
{
    [DllImport("Kernel32")]
    public static extern int LoadLibrary(String funcname);
    [DllImport("Kernel32")]
    public static extern int GetProcAddress(int handle, String funcname);
    [DllImport("Kernel32")]
    public static extern int FreeLibrary(int handle);

    public static Delegate GetFunctionAddress(int dllModule, String functionName, Type t)
    {
        int address = GetProcAddress(dllModule, functionName);
        if (address == 0)
        {
            return null;
        }
        else
            return Marshal.GetDelegateForFunctionPointer(new IntPtr(address), t);
    }

    public static Delegate GetDelegateFromIntPtr(IntPtr address, Type t)
    {
        if (address == IntPtr.Zero)
        {
            return null;
        }
        else
            return Marshal.GetDelegateForFunctionPointer(address, t);
    }

    public static Delegate GetDelegateFromIntPtr(int address, Type t)
    {
        if (address == 0)
        {
            return null;
        }
        else
            return Marshal.GetDelegateForFunctionPointer(new IntPtr(address), t);
    }

}

2.引用后台

　　1.创建委托delegate

　　public delegate bool SaveXxjToXml(string cnnStr, string xxjfile); 参数返回值，对应要引用的方法

　　2.引用类库方法

 　　　　string msg = string.Empty;
　　　　 //加载类库
        int hModule = DLLWrapper.LoadLibrary(Server.MapPath("~/dll/SaveToXml.dll"));
        if (hModule == 0)
        {
            msg = "导入信息价类库不存在，或者路径错误，请联系管理员。";
        }
        //注册委托
        SaveXxjToXml sxtx = (SaveXxjToXml)DLLWrapper.GetFunctionAddress(hModule, "SaveXxjToXml", typeof(SaveXxjToXml));
        if (sxtx==null)
        {
            DLLWrapper.FreeLibrary(hModule);
            msg = "导入信息价类库的方法不存在，请联系管理员。";
        }
        //调用注册后的委托
        bool result = sxtx(cnnStr, Server.MapPath(path));
            if (result)
                msg = "导入成功。";
            else
                msg = "导入失败。";