[C#.Net]全局钩子实现USB扫码枪无焦点状态下扫入

[C#.Net]全局钩子实现USB扫码枪无焦点状态下扫入
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）

using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.InteropServices;
using System.Reflection;
using System.Diagnostics;
namespace SaomiaoTest2
{/// <summary>/// 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/// </summary>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;//Ascllpublic 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<List<EventMsg>> _keys = new List<List<EventMsg>>();private List<int> _keydown = new List<int>();   // 保存组合键状态  private List<string> _result = new List<string>();  // 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<int> 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<EventMsg>());_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<EventMsg>());_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();  }  }
}

100个赞同这句【其实上面的代码都是复制这位大侠的，真心觉得大侠太厉害了，解决多年的疑惑，保留纪念】

https://www.cnblogs.com/TBW-Superhero/p/8659306.html

真的很好很全很细，感谢作者

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[C#.Net]全局钩子实现USB扫码枪无焦点状态下扫入

[C#.Net]全局钩子实现USB扫码枪无焦点状态下扫入

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