3年前写了一篇《USB口的红外条形码扫描器的另类使用》，不过相关代码是VB编写，在这几年之间，有许多网友提出需要C#版的，起初还以为由VB修改C#应该很容易，最近研究了一下，发现C#和VB调用API的机制还是有所不同的，在迁移的过程中还是会遇到不少问题，所以我专门抽时间做了一个基于C#的程序。

      【目前的条形码扫描器有点类似外接键盘（其实从消息传送上它就相当于一个键盘），把输入焦点定位到可输入的控件上，一扫描相应的条形码信息就输入到文本框中去了，但是如果没有输入焦点，或另一个不相干的程序获得输入焦点，那就有点乱套了。我想实现的是，不管什么情况，只要扫描器一工作，我的程序就能自动激活，并能获得当前输入的条形码信息。 实现思路：我用的是litele牌的USB口的红外条形码扫描器，仔细分析了一下，扫描成功后，以键盘按键消息的形式把条形码输入信息通知给系统。这样通过键盘钩子就可以方便的获得该信息了。但是，怎样区分信息是键盘还是条形码输入的哪？很简单，条形码扫描器在很短的时间内输入了至少3个字符以上信息，并且以“回车”作为结束字符，在这种思想指引下，很完美的实现了预定功能。】

     VB相关的代码请见：

    

 

    

 

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窗体相关代码：

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·········10········20········30········40········50········60········70········80········90········100·······110·······120·······130·······140·······150  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);                }            }        }    }            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：

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·········10········20········30········40········50········60········70········80········90········100·······110·······120·······130·······140·······150 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;            }        }    }   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;         }     } }  

    

 【注意】和VB程序不同，要想测试实际的效果，必须执行编译后的Exe文件，在开发环境直接运行会没有效果的。

 

 

本文转自yefanqiu51CTO博客，原文链接：http://blog.51cto.com/yfsoft/323420，如需转载请自行联系原作者