红外条码扫描器的另类使用C#版

     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：http://blog.csdn.net/yefanqiu/archive/2006/08/30/1144881.aspx

窗体相关代码：

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：

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。