日期:2014-05-18  浏览次数:20893 次

控制usb的问题
我想使用CreateFile和WriteFile来控制usb口的针式打印机,用SetupDi系列方法来找到打印机端口,但却只能找到USB键盘及鼠标,U盘或者打印机都找不到,请问这是什么原因?我的代码如下,是C#的代码
C# code

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Runtime.InteropServices;
using System.Threading;
using System.Collections;
using System.IO;

namespace USB
{
    class Class1
    {
        //以下是调用windows的API的函数
        //获得GUID
        [DllImport("hid.dll")]
        public static extern void HidD_GetHidGuid(ref Guid HidGuid);
        Guid guidHID = Guid.Empty;
        //过滤设备,获取需要的设备
        [DllImport("setupapi.dll", SetLastError = true)]
        public static extern IntPtr SetupDiGetClassDevs(ref Guid ClassGuid, uint Enumerator, IntPtr HwndParent, DIGCF Flags);
        IntPtr hDevInfo;
        //获取设备,true获取到
        [DllImport("setupapi.dll", CharSet = CharSet.Auto, SetLastError = true)]
        public static extern Boolean SetupDiEnumDeviceInterfaces(IntPtr hDevInfo, IntPtr devInfo, ref Guid 

interfaceClassGuid, UInt32 memberIndex, ref SP_DEVICE_INTERFACE_DATA deviceInterfaceData);
        public struct SP_DEVICE_INTERFACE_DATA
        {
            public int cbSize;
            public Guid interfaceClassGuid;
            public int flags;
            public int reserved;
        }

        [StructLayout(LayoutKind.Sequential)]
        private struct OVERLAPPED
        {
            int Internal;
            int InternalHigh;
            int Offset;
            int OffSetHigh;
            int hEvent;
        }

        // 获取接口的详细信息 必须调用两次 第1次返回长度 第2次获取数据
        [DllImport("setupapi.dll", SetLastError = true, CharSet = CharSet.Auto)]
        private static extern bool SetupDiGetDeviceInterfaceDetail(IntPtr deviceInfoSet, ref SP_DEVICE_INTERFACE_DATA 

deviceInterfaceData, IntPtr

deviceInterfaceDetailData,
            int deviceInterfaceDetailDataSize, ref int requiredSize, SP_DEVINFO_DATA deviceInfoData);
        [StructLayout(LayoutKind.Sequential)]
        public class SP_DEVINFO_DATA
        {
            public int cbSize = Marshal.SizeOf(typeof(SP_DEVINFO_DATA));
            public Guid classGuid = Guid.Empty; // temp
            public int devInst = 0; // dumy
            public int reserved = 0;
        }

        [StructLayout(LayoutKind.Sequential, Pack = 2)]
        internal struct SP_DEVICE_INTERFACE_DETAIL_DATA
        {
            internal int cbSize;
            internal short devicePath;
        }

        public enum DIGCF
        {
            DIGCF_DEFAULT = 0x1,
            DIGCF_PRESENT = 0x2,
            DIGCF_ALLCLASSES = 0x4,
            DIGCF_PROFILE = 0x8,
            DIGCF_DEVICEINTERFACE = 0x10
        }

        //获取设备文件
        [DllImport("kernel32.dll", SetLastError = true)]
        private static extern int CreateFile(
            string lpFileName,                            // file name
            uint dwDesiredAccess,                        // access mode
            uint dwShareMode,                            // share mode
            uint lpSecurityAttributes,                    // SD
            uint dwCreationDisposition,                    // how to create
            uint dwFlagsAndAttributes,                    // file attributes
            uint hTemplateFile                            // handle to template file
            );
        //读取设备文件
        [DllImport("Kernel32.dll", SetLastError = true)]
        private static extern bool ReadFile
            (
                IntPtr hFile,
                byte[] lpBuffer,
                uint nNumberOfBytesToRead,
                ref uint lpNumberOfBytesRead,
                IntPtr lpOverlapped
            );

        [DllImport("kernel32.dll")]
        private static extern b