条码扫描器接口编程(C#)

条码扫描器接口编程（C#）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。

】窗体相关代码：view plaincopy to clipboardprint? .........10........20........30........40........50........60........70........80........90........100.......110.......120.......130.......140. (150)using System;using System.Collections.Generic;using ponentModel;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：view plaincopy to clipboardprint? .........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; //AscIIpublic 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 = 13hKeyboardHook = 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】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。