USB扫码枪无焦点输入到指定页面、指定文件框中

最近在处理一个工控制软件，需要使用到无线扫码枪通过USB输入条码，并触发相应的数据处理，一般用途中通过USB扫码枪输入到指定文本框需要该文本框获得焦点才能正常输入并触发相应的程序处理过程。但在实际使用过程中，由于程序是有多个窗口，有条码输入的窗口，也有历史数据查询的窗口，存在多人操作的情况，有人在用无线条码枪扫码，有人在查询窗口查询数据。在这种情况下，往往扫码输入的窗口不在当前激活的页面，扫码后就不能执行相应的过程。经过参考其他大神的作业。都过修改，以下作业，可以实现USB扫码枪无焦点输入到指定页面、指定文件框中，可以实现多人操作，不会影响扫码枪的输入及数据处理的过程。

新建工程添一个MDIParent窗口，两个FORM窗口。第一步添加一个类(ScanerHook)，代码如下:

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks;

namespace SCAN
{

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);public int hKeyboardHook = 0;//声明键盘钩子处理的初始值public 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;}public 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;}}

}

第二步，修改MDIparent的代码如下： //在父级窗口声明

    public  static ScanerHook listener = new ScanerHook();public MDIParent1(){InitializeComponent();//添加以下代码listener.ScanerEvent += Listener_ScanerEvent;}private void MDIParent1_Load(object sender, EventArgs e){  //添加以下代码listener.Start();}private void MDIParent1_FormClosed(object sender, FormClosedEventArgs e){  //添加以下代码listener.Stop();}private void Listener_ScanerEvent(ScanerHook.ScanerCodes codes){}

第三步，在需要输入条码窗口（这里的窗口是form1）,添加以下代码：

public Form1()
{
InitializeComponent();
//需要监听扫码枪输入的窗口中添加此行
MDIParent1.listener.ScanerEvent += Listener_ScanerEvent;
}
//扫码枪信息输入处理
private void Listener_ScanerEvent(ScanerHook.ScanerCodes codes)
{
//显示输入的条码
textBox2.Text = codes.Result;
}

本作业复制参考以下大神的作业，分享是美德，感谢原作者的分享！

https://www.cnblogs.com/TBW-Superhero/p/8659306.html
本作业代码下载地址：
https://download.csdn.net/download/weixin_44002308/87164353?spm=1001.2014.3001.5501