关于SetupDiEnumDeviceInfo枚举设备返回false问题的解决办法

现象：我的程序中有个功能是要枚举设备。代码如下， 在XP 32位系统下运行没有问题，到Win7 64位系统时则不能枚举。调试发现SetupDiEnumDeviceInfo返回false。

       

 public static List GetDeviceProperty(string portname)
        {
            List HWList = new List();
            try
            {
                Guid myGUID = System.Guid.Empty;
                IntPtr hDevInfo = SetupDiGetClassDevs(ref myGUID, 0, IntPtr.Zero, DIGCF_ALLCLASSES | DIGCF_PRESENT);
                if (hDevInfo.ToInt32() == INVALID_HANDLE_VALUE)
                {
                    throw new Exception("Invalid Handle");
                }
                SP_DEVINFO_DATA DeviceInfoData;
                DeviceInfoData = new SP_DEVINFO_DATA();
                DeviceInfoData.cbSize = 28;
                DeviceInfoData.devInst = 0;
                DeviceInfoData.classGuid = System.Guid.Empty;
                DeviceInfoData.reserved = 0;
                UInt32 i;
                StringBuilder property = new StringBuilder("");
                property.Capacity = MAX_DEV_LEN;
                for (i = 0; SetupDiEnumDeviceInfo(hDevInfo, i, DeviceInfoData); i++)
                {
                    SetupDiGetDeviceRegistryProperty(hDevInfo, DeviceInfoData, (uint)SPDRP_CLASS, 0, property, (uint)property.Capacity, IntPtr.Zero);
                    if (property.ToString().ToLower() != "ports")
                    {
                        continue;
                    }
                    SetupDiGetDeviceRegistryProperty(hDevInfo, DeviceInfoData, (uint)SPDRP_FRIENDLYNAME, 0, property, (uint)property.Capacity, IntPtr.Zero);


                    if (!property.ToString().ToLower().Contains(portname.ToLower()))
                        continue;//找到对应于portname的设备
                    string port = property.ToString().Trim().Substring(property.ToString().IndexOf("("));
                    port = port.Replace("(", "").Replace(")", "");
                    HWList.Add(port);
                    break;
                }
                Console.Write(Marshal.GetLastWin32Error().ToString());                
                SetupDiDestroyDeviceInfoList(hDevInfo);
            }
            catch (Exception ex)
            {
                throw new Exception("枚举设备列表出错", ex);
            }
            return HWList;
        }

分析原因： 是32位和64位系统差异造成。

解决办法：判断是否为64位系统。

                if (Environment.Is64BitOperatingSystem)
                    DeviceInfoData.cbSize = 32;//(16,4,4,4)
                else
                    DeviceInfoData.cbSize = 28;