C#--USB扫码枪实现无焦点状态下扫入

以下内容是复制这个大神的文章，解决了USB扫码枪无焦点扫码的问题，非常感谢，我留个笔记

 

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

 

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）

3，代码实现

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using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks; using System.Diagnostics; using System.Runtime.InteropServices;     namespace Helper {     public class BarcodeScannerHelper     {         //public delegate void ScanerDelegate(ScanerCodes codes);         public delegate void ScanerDelegate(string 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);           /// <summary>         /// 声明键盘钩子处理的初始值         /// </summary>         private int hKeyboardHook = 0;         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（设立一道卡子，盘查需要的信息）         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 （卸载很重要，卡子设多了会造成拥堵）         private static extern bool UnhookWindowsHookEx(int idHook);         [DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]         //继续下个钩子 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）         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 BarcodeScannerHelper()         {         }         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);                 ScanerEvent(codes.Result);             }             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                     //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;                     }                       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;         }     } }

　　

4，在项目中使用

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namespace Test {     public partial class Form1 : Form     {         Helper.BarcodeScannerHelper scannerListener=new BarcodeScannerHelper();         public Form1()         {             scannerListener.ScanerEvent += ScannerListener_ScanerEvent;         }           private void ScannerListener_ScanerEvent(string codes)         {             this.ricScanContent2.AppendText(codes+"\n");         }             private void Form1_Load(object sender, EventArgs e)         {             this.scannerListener.Start();         }           private void Form1_FormClosing(object sender, FormClosingEventArgs e)         {                this.scannerListener.Stop();         }     } }