using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Diagnostics;using System.Runtime.InteropServices;namespace **.Forms{    /// 
    /// 获取键盘输入或者USB扫描枪数据 可以是没有焦点 应为使用的是全局钩子    /// USB扫描枪 是模拟键盘按下    /// 这里主要处理扫描枪的值，手动输入的值不太好处理    /// 
    public class BardCodeHook    {        public delegate void BardCodeDeletegate(BarCodes barCode);        public event BardCodeDeletegate BarCodeEvent;        //定义成静态，这样不会抛出回收异常        private static HookProc hookproc;        public struct BarCodes        {            public int VirtKey;//虚拟吗            public int ScanCode;//扫描码            public string KeyName;//键名            public uint Ascll;//Ascll            public char Chr;//字符            public string OriginalChrs; //原始 字符            public string OriginalAsciis;//原始 ASCII            public string OriginalBarCode;  //原始数据条码            public bool IsValid;//条码是否有效            public DateTime Time;//扫描时间,            public string BarCode;//条码信息   保存最终的条码        }        private struct EventMsg        {            public int message;            public int paramL;            public int paramH;            public int Time;            public int hwnd;        }        #region DllImport        [DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]        private static extern int SetWindowsHookEx(int idHook, HookProc lpfn, IntPtr hInstance, int threadId);        [DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]        private static extern bool UnhookWindowsHookEx(int idHook);        [DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]        private static extern int CallNextHookEx(int idHook, int nCode, Int32 wParam, IntPtr lParam);        [DllImport("user32", EntryPoint = "GetKeyNameText")]        private static extern int GetKeyNameText(int IParam, StringBuilder lpBuffer, int nSize);        [DllImport("user32", EntryPoint = "GetKeyboardState")]        private static extern int GetKeyboardState(byte[] pbKeyState);        [DllImport("user32", EntryPoint = "ToAscii")]        private static extern bool ToAscii(int VirtualKey, int ScanCode, byte[] lpKeySate, ref uint lpChar, int uFlags);        [DllImport("kernel32.dll")]        public static extern IntPtr GetModuleHandle(string name);        #endregion        delegate int HookProc(int nCode, Int32 wParam, IntPtr lParam);        BarCodes barCode = new BarCodes();        int hKeyboardHook = 0;        StringBuilder sbBarCode = new StringBuilder();        private int KeyboardHookProc(int nCode, Int32 wParam, IntPtr lParam)        {            int i_calledNext = -10;            if (nCode == 0)            {                EventMsg msg = (EventMsg)Marshal.PtrToStructure(lParam, typeof(EventMsg));                if (wParam == 0x100)//WM_KEYDOWN=0x100                {                    barCode.VirtKey = msg.message & 0xff;//虚拟码                    barCode.ScanCode = msg.paramL & 0xff;//扫描码                    StringBuilder strKeyName = new StringBuilder(225);                    if (GetKeyNameText(barCode.ScanCode * 65536, strKeyName, 255) > 0)                    {                        barCode.KeyName = strKeyName.ToString().Trim(new char[] { ' ', '\0' });                    }                    else                    {                        barCode.KeyName = "";                    }                    byte[] kbArray = new byte[256];                    uint uKey = 0;                    GetKeyboardState(kbArray);                    if (ToAscii(barCode.VirtKey, barCode.ScanCode, kbArray, ref uKey, 0))                    {                        barCode.Ascll = uKey;                        barCode.Chr = Convert.ToChar(uKey);                        barCode.OriginalChrs += " " + Convert.ToString(barCode.Chr);                        barCode.OriginalAsciis += " " + Convert.ToString(barCode.Ascll);                        barCode.OriginalBarCode += Convert.ToString(barCode.Chr);                    }                    TimeSpan ts = DateTime.Now.Subtract(barCode.Time);                    if (ts.TotalMilliseconds > 50)                    {
    //时间戳，大于50 毫秒表示手动输入                        sbBarCode.Remove(0, sbBarCode.Length);                        sbBarCode.Append(barCode.Chr.ToString());                        barCode.OriginalChrs = " " + Convert.ToString(barCode.Chr);                        barCode.OriginalAsciis = " " + Convert.ToString(barCode.Ascll);                        barCode.OriginalBarCode = Convert.ToString(barCode.Chr);                    }                    else                    {                        if ((msg.message & 0xff) == 13 && sbBarCode.Length > 3)                        {
    //回车                            barCode.BarCode = barCode.OriginalBarCode;                            barCode.IsValid = true;                            sbBarCode.Remove(0, sbBarCode.Length);                        }                        sbBarCode.Append(barCode.Chr.ToString());                    }                    try                    {                        if (BarCodeEvent != null && barCode.IsValid)                        {                            //barCode.BarCode = barCode.BarCode.Replace("\b", "").Replace("\0","");  可以不需要 因为大于50毫秒已经处理                            //先进行 WINDOWS事件往下传                            i_calledNext = CallNextHookEx(hKeyboardHook, nCode, wParam, lParam);                            GC.KeepAlive(hookproc);                            BarCodeEvent(barCode);//触发事件                            barCode.BarCode = "";                            barCode.OriginalChrs = "";                            barCode.OriginalAsciis = "";                            barCode.OriginalBarCode = "";                        }                    }                    catch                    {                    }                    finally                    {                        barCode.IsValid = false; //最后一定要 设置barCode无效                        barCode.Time = DateTime.Now;                    }                }            }            if (i_calledNext == -10)            {                i_calledNext = CallNextHookEx(hKeyboardHook, nCode, wParam, lParam);                GC.KeepAlive(hookproc);            }            return i_calledNext;        }        /// 
        /// 安装钩子        /// 
        /// 
             public bool Start()        {            if (hKeyboardHook == 0)            {                hookproc = new HookProc(KeyboardHookProc);                //GetModuleHandle 函数 替代 Marshal.GetHINSTANCE                //防止在 framework4.0中 注册钩子不成功                IntPtr modulePtr = GetModuleHandle(Process.GetCurrentProcess().MainModule.ModuleName);                //WH_KEYBOARD_LL=13                //全局钩子 WH_KEYBOARD_LL                //  hKeyboardHook = SetWindowsHookEx(13, hookproc, Marshal.GetHINSTANCE(Assembly.GetExecutingAssembly().GetModules()[0]), 0);                hKeyboardHook = SetWindowsHookEx(13, hookproc, modulePtr, 0);                //IntPtr intPtr = Marshal.GetHINSTANCE(System.Reflection.Assembly.GetExecutingAssembly().GetModules()[0]);                //hKeyboardHook = SetWindowsHookEx(13, hookproc, intPtr, 0);                GC.KeepAlive(hookproc);            }            return (hKeyboardHook != 0);        }        /// 
        /// 卸载钩子        /// 
        /// 
             public bool Stop()        {            if (hKeyboardHook != 0)            {                return UnhookWindowsHookEx(hKeyboardHook);            }            return true;        }    }}

使用方法：

private void Form_Load(object sender, EventArgs e)        {            bardCodeHook.Start();        bardCodeHook.BarCodeEvent += bardCodeHook_BarCodeEvent;        }        private void Form_FormClosed(object sender, FormClosedEventArgs e)        {            bardCodeHook.Stop();            bardCodeHook.BarCodeEvent -= bardCodeHook_BarCodeEvent;        }