C# Winform中无焦点状态下获取键盘输入或者USB扫描枪数据

/// <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;//Ascll
public char Chr;//字符
public string OriginalChrs; //原始 字符
public string OriginalAsciis;//原始 ASCII

public string OriginalBarCode; //原始数据条码

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 = "";
StringBuilder sbBarCode = new StringBuilder();

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();
sbBarCode.Remove(0, sbBarCode.Length);
sbBarCode.Append(barCode.Chr.ToString());
barCode.OriginalChrs = " " + Convert.ToString(barCode.Chr);
barCode.OriginalAsciis = " " + Convert.ToString(barCode.Ascll);
barCode.OriginalBarCode = Convert.ToString(barCode.Chr);
}
else
{
sbBarCode.Append(barCode.Chr.ToString());
if ((msg.message & 0xff) == 13 && sbBarCode.Length > 3)
{//回车
//barCode.BarCode = strBarCode;
barCode.BarCode = sbBarCode.ToString();// barCode.OriginalBarCode;
barCode.IsValid = true;
sbBarCode.Remove(0, sbBarCode.Length);
}
//strBarCode += barCode.Chr.ToString();
}
barCode.Time = DateTime.Now;
try
{
if (BarCodeEvent != null && barCode.IsValid)
{
AsyncCallback callback = new AsyncCallback(AsyncBack);
//object obj;
Delegate[] delArray = BarCodeEvent.GetInvocationList();
//foreach (Delegate del in delArray)
foreach (BardCodeDeletegate del in delArray)
{
try
{
//方法1
//obj = del.DynamicInvoke(barCode);
//方法2
del.BeginInvoke(barCode, callback, del);//异步调用防止界面卡死
}
catch (Exception ex)
{
throw ex;
}
}
//BarCodeEvent(barCode);//触发事件
barCode.BarCode = "";
barCode.OriginalChrs = "";
barCode.OriginalAsciis = "";
barCode.OriginalBarCode = "";
}
}
catch (Exception)
{
throw;
}
finally
{
barCode.IsValid = false; //最后一定要 设置barCode无效
barCode.Time = DateTime.Now;
}
}
}
return CallNextHookEx(hKeyboardHook, nCode, wParam, lParam);
}

//异步返回方法
public void AsyncBack(IAsyncResult ar)
{
BardCodeDeletegate del = ar.AsyncState as BardCodeDeletegate;
del.EndInvoke(ar);
}

//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;
}

     }

 

页面中用法：

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;

namespace Common
{
    public partial class FrmMain : Form
    {
        BardCodeHooK BarCode = new BardCodeHooK();
        public FrmMain()
        {
            InitializeComponent();
            BarCode.BarCodeEvent += new BardCodeHooK.BardCodeDeletegate(BarCode_BarCodeEvent);
        }

        private delegate void ShowInfoDelegate(BardCodeHooK.BarCodes barCode);
        private void ShowInfo(BardCodeHooK.BarCodes barCode)
        {
            if (this.InvokeRequired)
            {
                this.BeginInvoke(new ShowInfoDelegate(ShowInfo), new object[] { barCode });
            }
            else
            {
                textBox1.Text = barCode.KeyName;
                textBox2.Text = barCode.VirtKey.ToString();
                textBox3.Text = barCode.ScanCode.ToString();
                textBox4.Text = barCode.Ascll.ToString();
                textBox5.Text = barCode.Chr.ToString();
                textBox6.Text = barCode.IsValid? barCode.BarCode : "";//是否为扫描枪输入，如果为true则是 否则为键盘输入
                textBox7.Text += barCode.KeyName;
                //MessageBox.Show(barCode.IsValid.ToString());
            }
        }

        //C#中判断扫描枪输入与键盘输入

        //Private DateTime _dt = DateTime.Now;  //定义一个成员函数用于保存每次的时间点
        //private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
        //{
        //    DateTime tempDt = DateTime.Now;          //保存按键按下时刻的时间点
        //    TimeSpan ts = tempDt .Subtract(_dt);     //获取时间间隔
        //    if (ts.Milliseconds > 50)                           //判断时间间隔，如果时间间隔大于50毫秒，则将TextBox清空
        //        textBox1.Text = "";
        //    dt = tempDt ;
        //}

        void BarCode_BarCodeEvent(BardCodeHooK.BarCodes barCode)
        {
            ShowInfo(barCode);
        }

        private void FrmMain_Load(object sender, EventArgs e)
        {
            BarCode.Start();
        }

        private void FrmMain_FormClosed(object sender, FormClosedEventArgs e)
        {
            BarCode.Stop();
        }

        private void textBox6_TextChanged(object sender, EventArgs e)
        {
            if (textBox6.Text.Length > 0)
            {
                MessageBox.Show("条码长度：" + textBox6.Text.Length + "\n条码内容：" + textBox6.Text, "系统提示");
            }
        }
    }
}