3年前寫了一篇《 USB口的紅外條形碼掃描器的另類使用 》，不過相關代碼是VB編寫，在這幾年之間，有許多網友提出需要C#版的，起初還以為由VB修改C#應該很容易，最近研究了一下，發現C#和VB調用API的機制還是有所不同的，在遷移的過程中還是會遇到不少問題，所以我專門抽時間做了一個基于C#的程序。

【目前的條形碼掃描器有點類似外接鍵盤（其實從消息傳送上它就相當于一個鍵盤），把輸入焦點定位到可輸入的控件上，一掃描相應的條形碼信息就輸入到文本框中去了，但是如果沒有輸入焦點，或另一個不相干的程序獲得輸入焦點，那就有點亂套了。我想實現的是，不管什么情況，只要掃描器一工作，我的程序就能自動激活，并能獲得當前輸入的條形碼信息。 實現思路：我用的是litele牌的USB口的紅外條形碼掃描器，仔細分析了一下，掃描成功后，以鍵盤按鍵消息的形式把條形碼輸入信息通知給系統。這樣通過鍵盤鉤子就可以方便的獲得該信息了。但是，怎樣區分信息是鍵盤還是條形碼輸入的哪？很簡單，條形碼掃描器在很短的時間內輸入了至少3個字符以上信息，并且以“回車”作為結束字符，在這種思想指引下，很完美的實現了預定功能?！?

VB相關的代碼請見： http://blog.csdn.net/yefanqiu/archive/2006/08/30/1144881.aspx

窗體相關代碼：

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 類：

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; //虛擬碼 public int ScanCode; //掃描碼 public string KeyName; //鍵名 public uint AscII; //AscII public char Chr; //字符 public string BarCode; //條碼信息 public bool IsValid; //條碼是否有效 public DateTime Time; //掃描時間 } 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; //虛擬碼 barCode.ScanCode = msg.paramL & 0xff; //掃描碼 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) //回車 { barCode.BarCode = strBarCode; barCode.IsValid = true; } strBarCode += barCode.Chr.ToString(); } barCode.Time = DateTime.Now; if (BarCodeEvent != null) BarCodeEvent(barCode); //觸發事件 barCode.IsValid = false; } } return CallNextHookEx(hKeyboardHook, nCode, wParam, lParam); } // 安裝鉤子 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); } // 卸載鉤子 public bool Stop() { if (hKeyboardHook != 0) { return UnhookWindowsHookEx(hKeyboardHook); } return true; } } }

【注意】和VB程序不同，要想測試實際的效果，必須執行編譯后的Exe文件，在開發環境直接運行會沒有效果的。

紅外條碼掃描器的另類使用C#版