C# 全局鉤子實現掃碼槍獲取信息

1.掃描槍獲取數據原理基本相當于鍵盤數據，獲取掃描槍掃描出來的數據，一般分為兩種實現方式。

　　a）文本框輸入獲取焦點，掃描后自動顯示在文本框內。

　　b）使用鍵盤鉤子，勾取掃描槍虛擬按鍵，根據按鍵頻率進行手動輸入和掃描槍掃描判斷。

2.要實現系統鉤子其實很簡單，調用三個Win32的API即可。

SetWindowsHookEx?用于設置鉤子。（設立一道卡子，盤查需要的信息）

CallNextHookEx?用于傳遞鉤子（消息是重要的，所以從哪里來，就應該回到哪里去，除非你決定要封鎖消息）

UnhookWindowsHookEx?卸載鉤子（卸載很重要，卡子設多了會造成擁堵）

版本一：

using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.InteropServices;
using System.Reflection;
using System.Diagnostics;
namespace SaomiaoTest2
{/// <summary>/// 獲取鍵盤輸入或者USB掃描槍數據 可以是沒有焦點 應為使用的是全局鉤子/// USB掃描槍 是模擬鍵盤按下/// 這里主要處理掃描槍的值，手動輸入的值不太好處理/// </summary>public class BardCodeHooK{public delegate void BardCodeDeletegate(BarCodes barCode);public event BardCodeDeletegate BarCodeEvent;//定義成靜態，這樣不會拋出回收異常private static HookProc hookproc;public struct BarCodes{public int VirtKey;//虛擬嗎public int ScanCode;//掃描碼public string KeyName;//鍵名public uint Ascll;//Ascllpublic char Chr;//字符public string BarCode;//條碼信息   保存最終的條碼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 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;//虛擬嗎barCode.ScanCode = msg.paramL & 0xff;//掃描碼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){//時間戳，大于50 毫秒表示手動輸入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){hookproc = new HookProc(KeyboardHookProc);//GetModuleHandle 函數 替代 Marshal.GetHINSTANCE//防止在 framework4.0中 注冊鉤子不成功IntPtr modulePtr = GetModuleHandle(Process.GetCurrentProcess().MainModule.ModuleName);//WH_KEYBOARD_LL=13//全局鉤子 WH_KEYBOARD_LL//  hKeyboardHook = SetWindowsHookEx(13, hookproc, Marshal.GetHINSTANCE(Assembly.GetExecutingAssembly().GetModules()[0]), 0);hKeyboardHook = SetWindowsHookEx(13, hookproc, modulePtr, 0);}return (hKeyboardHook != 0);}//卸載鉤子public bool Stop(){if (hKeyboardHook != 0){return UnhookWindowsHookEx(hKeyboardHook);}return true;}}
}

在實踐過程中，發現版本一的代碼只能掃描條形碼，如伴隨二維碼中的字母出現就不能正確獲取數據。

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;//聲明鍵盤鉤子處理的初始值private ScanerCodes codes = new ScanerCodes();//13為鍵盤鉤子//定義成靜態，這樣不會拋出回收異常private static HookProc hookproc;delegate int HookProc(int nCode, Int32 wParam, IntPtr lParam);[DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]　　　　 //設置鉤子private static extern int SetWindowsHookEx(int idHook, HookProc lpfn, IntPtr hInstance, int threadId);[DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]　　　　  //卸載鉤子private static extern bool UnhookWindowsHookEx(int idHook);[DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]        //繼續下個鉤子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")]　　　　  //獲取按鍵的狀態private static extern int GetKeyboardState(byte[] pbKeyState);[DllImport("user32", EntryPoint = "ToAscii")]　　　　  //ToAscii職能的轉換指定的虛擬鍵碼和鍵盤狀態的相應字符或字符private static extern bool ToAscii(int VirtualKey, int ScanCode, byte[] lpKeySate, ref uint lpChar, int uFlags);　　　　//int VirtualKey //[in] 指定虛擬關鍵代碼進行翻譯。　　　　　　//int uScanCode, // [in] 指定的硬件掃描碼的關鍵須翻譯成英文。高階位的這個值設定的關鍵，如果是（不壓）　　　　　　//byte[] lpbKeyState, // [in] 指針，以256字節數組，包含當前鍵盤的狀態。每個元素（字節）的數組包含狀態的一個關鍵。如果高階位的字節是一套，關鍵是下跌（按下）。在低比特，如/果設置表明，關鍵是對切換。在此功能，只有肘位的CAPS LOCK鍵是相關的。在切換狀態的NUM個鎖和滾動鎖定鍵被忽略。　　　　　　//byte[] lpwTransKey, // [out] 指針的緩沖區收到翻譯字符或字符。　　　　　　//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函數代替獲取當前實例的函數,防止鉤子失效public static extern IntPtr GetModuleHandle(string name);public ScanerHook(){}public bool Start(){if (hKeyboardHook == 0){hookproc = new HookProc(KeyboardHookProc);//GetModuleHandle 函數 替代 Marshal.GetHINSTANCE  //防止在 framework4.0中 注冊鉤子不成功  IntPtr modulePtr = GetModuleHandle(Process.GetCurrentProcess().MainModule.ModuleName);//WH_KEYBOARD_LL=13  //全局鉤子 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; // 指定輸入間隔為300毫秒以內時為連續輸入  private List<List<EventMsg>> _keys = new List<List<EventMsg>>();private List<int> _keydown = new List<int>();   // 保存組合鍵狀態  private List<string> _result = new List<string>();  // 返回結果集  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 記錄按鍵信息           // 首次按下按鍵  if (_keys.Count == 0){_keys.Add(new List<EventMsg>());_keys[0].Add(msg);_result.Add(string.Empty);}// 未釋放其他按鍵時按下按鍵  else if (_keydown.Count > 0){_keys[_keys.Count - 1].Add(msg);}// 單位時間內按下按鍵  else if (((TimeSpan)(DateTime.Now - _last)).TotalMilliseconds < ts){_keys[_keys.Count - 1].Add(msg);}// 從新記錄輸入內容  else{_keys.Add(new List<EventMsg>());_keys[_keys.Count - 1].Add(msg);_result.Add(string.Empty);}#endregion_last = DateTime.Now;#region 獲取鍵盤狀態// 記錄正在按下的按鍵  if (msg.paramH == 0 && !_keydown.Contains(msg.message)){_keydown.Add(msg.message);}// 清除已松開的按鍵  if (msg.paramH > 0 && _keydown.Contains(msg.message)){_keydown.Remove(msg.message);}#endregion#region 計算按鍵信息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{// 根據鍵盤狀態和shift緩存判斷輸出字符  _cur = ShiftChar(_key, isShift, _state).ToString();_result[_result.Count - 1] += _cur;}　　　　　　　　　　　　　　// 備選　　　　　　　　　　   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;}}
}

版本二中的代碼，實踐中發現出現了獲取掃描數據卻省略“+”加號的情況出現。

因此在版本二中備選處添加

//判斷是+ 強制添加+
else if (_key.Length == 5 && msg.paramH == 0&&msg.paramL==78&&msg.message==107)
{// 根據鍵盤狀態和shift緩存判斷輸出字符  _cur = Convert.ToChar('+').ToString();_result[_result.Count - 1] += _cur;
}

3.winform在無焦點情況下的使用方式

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();  }  }
}