// 条码扫描器

// 窗体部分相关代码：

using System; 
using System.Collections.Generic;   
using System.ComponentModel;   
using System.Data;   
using System.Drawing;   
using System.Text;   
using System.Windows.Forms;   
  
namespace ReadBadCode   
{   
    public partial class frmTest : Form   
    {   
        BarCodeHook BarCode = new BarCodeHook();   
        public frmTest()   
        {   
            InitializeComponent();   
            BarCode.BarCodeEvent += new BarCodeHook.BarCodeDelegate(BarCode_BarCodeEvent);   
        }   
  
        private delegate void ShowInfoDelegate(BarCodeHook.BarCodes barCode);   
        private void ShowInfo(BarCodeHook.BarCodes barCode)   
        {   
            if (this.InvokeRequired)   
            {   
                this.BeginInvoke(new ShowInfoDelegate(ShowInfo), new object[] { barCode });   
            }   
            else  
            {   
                textBox1.Text = barCode.KeyName;   
                textBox2.Text = barCode.VirtKey.ToString();   
                textBox3.Text = barCode.ScanCode.ToString();   
                textBox4.Text = barCode.AscII.ToString();   
                textBox5.Text = barCode.Chr.ToString();   
                textBox6.Text = barCode.IsValid ? barCode.BarCode : "";   
            }   
        }   
  
        void BarCode_BarCodeEvent(BarCodeHook.BarCodes barCode)   
        {   
            ShowInfo(barCode);   
        }   
  
        private void frmTest_Load(object sender, EventArgs e)   
        {   
            BarCode.Start();   
        }   
  
        private void frmTest_FormClosed(object sender, FormClosedEventArgs e)   
        {   
            BarCode.Stop();   
        }   
  
        private void textBox6_TextChanged(object sender, EventArgs e)   
        {   
            if (textBox6.Text.Length > 0)   
            {   
                MessageBox.Show(textBox6.Text);   
            }   
        }   
    }   
}   

BarCodeHook  类相关代码：

using System;   
using System.Collections.Generic;   
using System.Text;   
using System.Runtime.InteropServices;   
using System.Reflection;   
  
namespace ReadBadCode   
{   
    public class BarCodeHook   
    {   
        public delegate void BarCodeDelegate(BarCodes barCode);   
        public event BarCodeDelegate BarCodeEvent;   
  
        public struct BarCodes   
        {   
            public int VirtKey;      //虚拟码   
            public int ScanCode;     //扫描码   
            public string KeyName;   //键名   
            public uint AscII;       //AscII   
            public char Chr;         //字符   
  
            public string BarCode;   //条码信息   
            public bool IsValid;     //条码是否有效   
            public DateTime Time;    //扫描时间   
        }   
  
        private struct EventMsg   
        {   
            public int message;   
            public int paramL;   
            public int paramH;   
            public int Time;   
            public int hwnd;   
        }   
          
        [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 lParam, 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[] lpKeyState, ref uint lpChar, int uFlags);   
  
        delegate int HookProc(int nCode, Int32 wParam, IntPtr lParam);   
        BarCodes barCode = new BarCodes();   
        int hKeyboardHook = 0;   
        string strBarCode = "";   
  
        private int KeyboardHookProc(int nCode, Int32 wParam, IntPtr lParam)   
        {   
            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(255);   
                    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.AscII = uKey;   
                        barCode.Chr = Convert.ToChar(uKey);   
                    }   
  
                    if (DateTime.Now.Subtract(barCode.Time).TotalMilliseconds > 50)    
                    {   
                        strBarCode = barCode.Chr.ToString();   
                    }   
                    else  
                    {   
                        if ((msg.message & 0xff) == 13 && strBarCode.Length > 3)   //回车   
                        {   
                            barCode.BarCode = strBarCode;   
                            barCode.IsValid = true;   
                        }   
                        strBarCode += barCode.Chr.ToString();   
                    }   
  
                    barCode.Time = DateTime.Now;   
                    if (BarCodeEvent != null) BarCodeEvent(barCode);    //触发事件   
                    barCode.IsValid = false;   
                }   
            }   
            return CallNextHookEx(hKeyboardHook, nCode, wParam, lParam);             
        }   
           
        // 安装钩子    
        public bool Start()   
        {   
            if (hKeyboardHook == 0)   
            {   
                //WH_KEYBOARD_LL = 13   
                hKeyboardHook = SetWindowsHookEx(13, new HookProc(KeyboardHookProc), Marshal.GetHINSTANCE(Assembly.GetExecutingAssembly().GetModules()[0]), 0);   
            }   
            return (hKeyboardHook != 0);   
        }   
  
        // 卸载钩子    
        public bool Stop()   
        {   
            if (hKeyboardHook != 0)   
            {   
                return UnhookWindowsHookEx(hKeyboardHook);   
            }   
            return true;   
        }   
    }