目录
1、使用需求
2、实现思路
3、接入钩子win32接口API
4、声明键盘钩子消息结构
5、安装键盘钩子
6、使用实例
7、注意事项
1、使用需求
最近接收到需求，需要通过扫描二维码将获取到的信息填充到窗体里面。
2、实现思路
通过查看二维扫描枪的说明书可知，扫描枪传输数据可支持标准键盘模拟输入，于是可通过键盘钩子监听事件来实现。
3、接入钩子win32接口API
//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）
[DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
private static extern int SetWindowsHookEx(int idHook, HookProc lpfn, IntPtr hInstance, int threadId);//卸载钩子 （卸载很重要，卡子设多了会造成拥堵）
[DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
private static extern bool UnhookWindowsHookEx(int idHook);//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）
[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);//获取按键的状态
[DllImport("user32", EntryPoint = "GetKeyboardState")]
private static extern int GetKeyboardState(byte[] pbKeyState);//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
[DllImport("user32", EntryPoint = "ToAscii")]
private static extern bool ToAscii(int VirtualKey, int ScanCode, byte[] lpKeySate, ref uint lpChar, int uFlags);//使用WINDOWS API函数代替获取当前实例的函数,防止钩子失效
[DllImport("kernel32.dll")]
public static extern IntPtr GetModuleHandle(string name);//使用WINDOWS API函数代替获取当前实例的函数,防止钩子失效
[DllImport("kernel32.dll")]
public static extern IntPtr GetModuleHandle(string name);4、声明键盘钩子消息结构
public struct EventMsg
{public int message;public int paramL;public int paramH;public int Time;public int hwnd;
}5、安装键盘钩子
//第二步：声明，定义委托
public delegate void ScanerDelegate(string codes);
public event ScanerDelegate ScanerEvent;/// <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.message == 161){msg.message -= 1;msg.paramH -= 1;}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;}
}6、使用实例
//创建钩子类
BarcodeScannerHelper scannerListener = new BarcodeScannerHelper();scannerListener.ScanerEvent += ScannerListener_ScanerEvent;
scannerListener.Start();//开始监听
//监听过程
//scannerListener.Stop();//停止监听//监听接收事件
private void ScannerListener_ScanerEvent(string codes)
{//将接收到的数据进行处理
}7、注意事项
部分扫描枪在区分大小写时用的是Left Shift，有的为Right Shift，两种处理方式有区别，需要特别注意，如果只处理一种会导致扫描出的字母均为小写，此实例已经两种方式均已经处理
