C#调用C语言写的dll，并发布web服务

创建ashx文件：

<%@ WebHandler Language="C#" Class="wgtochina" %>

using System;
using System.Web;
using System.Runtime.InteropServices;

public class wgtochina : IHttpHandler
{
    [DllImport("casmapi.dll", EntryPoint = "wgtochina", CharSet = CharSet.Ansi, CallingConvention = CallingConvention.Cdecl)]
    public static extern int do_wgtochina(int iFirst, int iProjType, int iZoneNum, double dCentMedian, double x, double y, ref double outX, ref double outY);

    public void ProcessRequest(HttpContext context)
    {
        int a = 99;
        double outX = 0;
        double outY = 0;
        try
        {
            int iFirst = System.Int32.Parse(context.Request.Params["iFirst"]);
            int iProjType = System.Int32.Parse(context.Request.Params["iProjType"]);
            int iZoneNum = System.Int32.Parse(context.Request.Params["iZoneNum"]);
            double dCentMedian = System.Double.Parse(context.Request.Params["dCentMedian"]);
            double x = System.Double.Parse(context.Request.Params["x"]);
            double y = System.Double.Parse(context.Request.Params["y"]);


            a = do_wgtochina(iFirst, iProjType, iZoneNum, dCentMedian, x, y, ref outX, ref outY);
        }
        catch (Exception ex)
        {
            context.Response.ContentType = "text/plain";
            context.Response.Write(ex.ToString());
            return;
        }
        string result = "";
        switch (a)
        {
            case -1:
                result = "无授权";
                break;
            case -2:
                result = "授权文件异常";
                break;
            case -3:
                result = "授权文件过期";
                break;
            case -4:
                result = "加密狗异常";
                break;
            case 0:
                result = "输入参数异常";
                break;
            case 1:
                result = "正常";
                break;
            default:
                result = "未知错误";
                break;
        }

        string json = "{\"status\":\"" + result + "\",\"outX\":" + outX + ",\"outY\":" + outY + "}";
        context.Response.ContentType = "text/plain";
        context.Response.Write(json);
    }

    public bool IsReusable
    {
        get
        {
            return false;
        }
    }
}

32位dll放在 C:\Windows\SysWOW64目录下，确保这个dll依赖的其他dll也在这个目录下
启用IIS7的32位兼容性
打开IIS管理器,点应用程序池
再点右边的"设置应用程序池默认设置"
再点启用32位应用程序,将false改成true
确定后就生效了

还有就是IIS用户要有对C:\temp目录的读写权限

还有就是要将.net和IIS关联起来在cmd下执行aspnet_regiis.exe –i