1.扫描枪获取数据原理基本相当于键盘数据，获取扫描枪扫描出来的数据，一般分为两种实现方式。
a）文本框输入获取焦点，扫描后自动显示在文本框内。
b）使用键盘钩子，勾取扫描枪虚拟按键，根据按键频率进行手动输入和扫描枪扫描判断。
2.要实现系统钩子其实很简单，调用三个Win32的API即可。
SetWindowsHookEx 用于设置钩子。（设立一道卡子，盘查需要的信息）
CallNextHookEx 用于传递钩子（消息是重要的，所以从哪里来，就应该回到哪里去，除非你决定要封锁消息）
UnhookWindowsHookEx 卸载钩子（卸载很重要，卡子设多了会造成拥堵）
版本一：
using System;using System.Collections.Generic;using System.Text;using System.Runtime.InteropServices;using System.Reflection;using System.Diagnostics;namespace SaomiaoTest2{ /// /// 获取键盘输入或者USB扫描枪数据 可以是没有焦点 应为使用的是全局钩子 /// USB扫描枪 是模拟键盘按下 /// 这里主要处理扫描枪的值，手动输入的值不太好处理 /// public class BardCodeHooK { public delegate void BardCodeDeletegate(BarCodes barCode); public event BardCodeDeletegate BarCodeEvent; //定义成静态，这样不会抛出回收异常 private static HookProc hookproc; public struct BarCodes { public int VirtKey;//虚拟吗 public int ScanCode;//扫描码 public string KeyName;//键名 public uint Ascll;//Ascll public char Chr;//字符 public string BarCode;//条码信息 保存最终的条码 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 IParam, 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[] lpKeySate, ref uint lpChar, int uFlags); [DllImport("kernel32.dll")] public static extern IntPtr GetModuleHandle(string name); 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;//虚拟吗 barCode.ScanCode = msg.paramL & 0xff;//扫描码 StringBuilder strKeyName = new StringBuilder(225); 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.Ascll = uKey; barCode.Chr = Convert.ToChar(uKey); } TimeSpan ts = DateTime.Now.Subtract(barCode.Time); if (ts.TotalMilliseconds > 50) { //时间戳，大于50 毫秒表示手动输入 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) { hookproc = new HookProc(KeyboardHookProc); //GetModuleHandle 函数 替代 Marshal.GetHINSTANCE //防止在 framework4.0中 注册钩子不成功 IntPtr modulePtr = GetModuleHandle(Process.GetCurrentProcess().MainModule.ModuleName); //WH_KEYBOARD_LL=13 //全局钩子 WH_KEYBOARD_LL // hKeyboardHook = SetWindowsHookEx(13, hookproc, Marshal.GetHINSTANCE(Assembly.GetExecutingAssembly().GetModules()[0]), 0); hKeyboardHook = SetWindowsHookEx(13, hookproc, modulePtr, 0); } return (hKeyboardHook != 0); } //卸载钩子 public bool Stop() { if (hKeyboardHook != 0) { return UnhookWindowsHookEx(hKeyboardHook); } return true; } }} 在实践过程中，发现版本一的代码只能扫描条形码，如伴随二维码中的字母出现就不能正确获取数据。
版本二：
using System;using System.Collections.Generic;using System.Diagnostics;using System.Runtime.InteropServices;using System.Text;namespace BarcodeScanner{ public class ScanerHook { public delegate void ScanerDelegate(ScanerCodes codes); public event ScanerDelegate ScanerEvent; //private const int WM_KEYDOWN = 0x100;//KEYDOWN
//private const int WM_KEYUP = 0x101;//KEYUP //private const int WM_SYSKEYDOWN = 0x104;//SYSKEYDOWN //private const int WM_SYSKEYUP = 0x105;//SYSKEYUP//private static int HookProc(int nCode, Int32 wParam, IntPtr lParam); private int hKeyboardHook = 0;//声明键盘钩子处理的初始值 private ScanerCodes codes = new ScanerCodes();//13为键盘钩子 //定义成静态，这样不会抛出回收异常 private static HookProc hookproc; delegate int HookProc(int nCode, Int32 wParam, IntPtr lParam); [DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)] //设置钩子 private static extern int SetWindowsHookEx(int idHook, HookProc lpfn, IntPtr hInstance, int threadId); [DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)] //卸载钩子 private static extern bool UnhookWindowsHookEx(int idHook); [DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)] //继续下个钩子 private static extern int CallNextHookEx(int idHook, int nCode, Int32 wParam, IntPtr lParam); [DllImport("user32", EntryPoint = "GetKeyNameText")] private static extern int GetKeyNameText(int IParam, StringBuilder lpBuffer, int nSize); [DllImport("user32", EntryPoint = "GetKeyboardState")] //获取按键的状态 private static extern int GetKeyboardState(byte[] pbKeyState); [DllImport("user32", EntryPoint = "ToAscii")] //ToAscii职能的转换指定的虚拟键码和键盘状态的相应字符或字符 private static extern bool ToAscii(int VirtualKey, int ScanCode, byte[] lpKeySate, ref uint lpChar, int uFlags); //int VirtualKey //[in] 指定虚拟关键代码进行翻译。
//int uScanCode, // [in] 指定的硬件扫描码的关键须翻译成英文。高阶位的这个值设定的关键，如果是（不压） //byte[] lpbKeyState, // [in] 指针，以256字节数组，包含当前键盘的状态。每个元素（字节）的数组包含状态的一个关键。如果高阶位的字节是一套，关键是下跌（按下）。在低比特，如/果设置表明，关键是对切换。在此功能，只有肘位的CAPS LOCK键是相关的。在切换状态的NUM个锁和滚动锁定键被忽略。 //byte[] lpwTransKey, // [out] 指针的缓冲区收到翻译字符或字符。 //uint fuState); // [in] Specifies whether a menu is active. This parameter must be 1 if a menu is active, or 0 otherwise.
[DllImport("kernel32.dll")] //使用WINDOWS API函数代替获取当前实例的函数,防止钩子失效 public static extern IntPtr GetModuleHandle(string name); public ScanerHook() { } public bool Start() { if (hKeyboardHook == 0) { hookproc = new HookProc(KeyboardHookProc); //GetModuleHandle 函数 替代 Marshal.GetHINSTANCE //防止在 framework4.0中 注册钩子不成功 IntPtr modulePtr = GetModuleHandle(Process.GetCurrentProcess().MainModule.ModuleName); //WH_KEYBOARD_LL=13 //全局钩子 WH_KEYBOARD_LL // hKeyboardHook = SetWindowsHookEx(13, hookproc, Marshal.GetHINSTANCE(Assembly.GetExecutingAssembly().GetModules()[0]), 0); hKeyboardHook = SetWindowsHookEx(13, hookproc, modulePtr, 0); } return (hKeyboardHook != 0); } public bool Stop() { if (hKeyboardHook != 0) { bool retKeyboard = UnhookWindowsHookEx(hKeyboardHook); hKeyboardHook = 0; return retKeyboard; } return true; } private int KeyboardHookProc(int nCode, Int32 wParam, IntPtr lParam) { EventMsg msg = (EventMsg)Marshal.PtrToStructure(lParam, typeof(EventMsg)); codes.Add(msg); if (ScanerEvent != null && msg.message == 13 && msg.paramH > 0 && !string.IsNullOrEmpty(codes.Result)) { ScanerEvent(codes); } return CallNextHookEx(hKeyboardHook, nCode, wParam, lParam); } public class ScanerCodes { private int ts = 100; // 指定输入间隔为300毫秒以内时为连续输入 private List > _keys = new List >(); private List _keydown = new List (); // 保存组合键状态 private List _result = new List (); // 返回结果集 private DateTime _last = DateTime.Now; private byte[] _state = new byte[256]; private string _key = string.Empty; private string _cur = string.Empty; public EventMsg Event { get { if (_keys.Count == 0) { return new EventMsg(); } else { return _keys[_keys.Count - 1][_keys[_keys.Count - 1].Count - 1]; } } } public List KeyDowns { get { return _keydown; } } public DateTime LastInput { get { return _last; } } public byte[] KeyboardState { get { return _state; } } public int KeyDownCount { get { return _keydown.Count; } } public string Result { get { if (_result.Count > 0) { return _result[_result.Count - 1].Trim(); } else { return null; } } } public string CurrentKey { get { return _key; } } public string CurrentChar { get { return _cur; } } public bool isShift { get { return _keydown.Contains(160); } } public void Add(EventMsg msg) { #region 记录按键信息 // 首次按下按键 if (_keys.Count == 0) { _keys.Add(new List ()); _keys[0].Add(msg); _result.Add(string.Empty); } // 未释放其他按键时按下按键 else if (_keydown.Count > 0) { _keys[_keys.Count - 1].Add(msg); } // 单位时间内按下按键 else if (((TimeSpan)(DateTime.Now - _last)).TotalMilliseconds < ts) { _keys[_keys.Count - 1].Add(msg); } // 从新记录输入内容 else { _keys.Add(new List ()); _keys[_keys.Count - 1].Add(msg); _result.Add(string.Empty); } #endregion _last = DateTime.Now; #region 获取键盘状态 // 记录正在按下的按键 if (msg.paramH == 0 && !_keydown.Contains(msg.message)) { _keydown.Add(msg.message); } // 清除已松开的按键 if (msg.paramH > 0 && _keydown.Contains(msg.message)) { _keydown.Remove(msg.message); } #endregion #region 计算按键信息 int v = msg.message & 0xff; int c = msg.paramL & 0xff; StringBuilder strKeyName = new StringBuilder(500); if (GetKeyNameText(c * 65536, strKeyName, 255) > 0) { _key = strKeyName.ToString().Trim(new char[] { ' ', '\0' }); GetKeyboardState(_state); if (_key.Length == 1 && msg.paramH == 0)// && msg.paramH == 0 { // 根据键盘状态和shift缓存判断输出字符 _cur = ShiftChar(_key, isShift, _state).ToString(); _result[_result.Count - 1] += _cur; } // 备选 else { _cur = string.Empty; } } #endregion } private char ShiftChar(string k, bool isShiftDown, byte[] state) { bool capslock = state[0x14] == 1; bool numlock = state[0x90] == 1; bool scrolllock = state[0x91] == 1; bool shiftdown = state[0xa0] == 1; char chr = (capslock ? k.ToUpper() : k.ToLower()).ToCharArray()[0]; if (isShiftDown) { if (chr >= 'a' && chr <= 'z') { chr = (char)((int)chr - 32); } else if (chr >= 'A' && chr <= 'Z') { if (chr=='Z') { string s = ""; } chr = (char)((int)chr + 32); } else { string s = "`1234567890-=[];',./"; string u = "~!@#$%^&*()_+{}:\"<>?"; if (s.IndexOf(chr) >= 0) { return (u.ToCharArray())[s.IndexOf(chr)]; } } } return chr; } } public struct EventMsg { public int message; public int paramL; public int paramH; public int Time; public int hwnd; } }}
版本二中的代码，实践中发现出现了获取扫描数据却省略“+”加号的情况出现。
因此在版本二中备选处添加
//判断是+ 强制添加+ else if (_key.Length == 5 && msg.paramH == 0&&msg.paramL==78&&msg.message==107)// && msg.paramH == 0 { // 根据键盘状态和shift缓存判断输出字符 _cur = Convert.ToChar('+').ToString(); _result[_result.Count - 1] += _cur; } 3.winform在无焦点情况下的使用方式：
using BarcodeScanner;using System;using System.Collections.Generic;using System.ComponentModel;using System.Data;using System.Drawing;using System.Linq;using System.Text;using System.Windows.Forms;namespace BarCodeTest{ public partial class Form1 : Form { private ScanerHook listener = new ScanerHook(); public Form1() { InitializeComponent(); listener.ScanerEvent += Listener_ScanerEvent; } private void Listener_ScanerEvent(ScanerHook.ScanerCodes codes) { textBox3.Text = codes.Result; } private void Form1_Load(object sender, EventArgs e) { listener.Start(); } private void Form1_FormClosed(object sender, FormClosedEventArgs e) { listener.Stop(); } }}