winfrom钩子实现无焦点扫码输入条码获取-最容易看懂的Demo

 在网上找了很长时间，都没有很简单的能看懂的Demo，因为工作需要，我自己完成一个简单的Demo，保证傻瓜都能看懂。

1. 钩子类

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

namespace ScanDemo
{
    class BarCodeHook
    {
        public delegate void BarCodeDelegate(BarCodes barCode);
        public event BarCodeDelegate BarCodeEvent;

        public struct BarCodes
        {
            public int VirtKey;      //虚拟码  
            public int ScanCode;     //扫描码  
            public string BarCode;   //条码信息  
            public bool IsValid;     //条码是否有效  
            public DateTime Time;    //扫描时间  
        }

        private struct EventMsg  //事件信息
        {
            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);

        delegate int HookProc(int nCode, Int32 wParam, IntPtr lParam);

        BarCodes barCode = new BarCodes();
        int hKeyboardHook = 0;
        public List<char> _barcode = new List<char>(100);
        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;  //虚拟码  
                    barCode.ScanCode = msg.paramL & 0xff;  //扫描码  

                    if (DateTime.Now.Subtract(barCode.Time).TotalMilliseconds > 100)
                    {
                        _barcode.Clear();
                    }
                    else
                    {
                        if ((msg.message & 0xff) == 13 && _barcode.Count > 0)   //回车  
                        {
                            barCode.BarCode = new String(_barcode.ToArray());
                            barCode.IsValid = true;
                            _barcode.Clear();
                        }
                    }

                    barCode.Time = DateTime.Now;
                    if (BarCodeEvent != null) BarCodeEvent(barCode);    //触发事件  
                    barCode.IsValid = false;
                    _barcode.Add(Convert.ToChar(msg.message & 0xff));
                }
            }
            return CallNextHookEx(hKeyboardHook, nCode, wParam, lParam);
        }

        private static HookProc hookproc;
        // 安装钩子   
        public bool Start()
        {
            if (hKeyboardHook == 0)
            {
                hookproc = new HookProc(KeyboardHookProc);
                //WH_KEYBOARD_LL = 13  
                hKeyboardHook = SetWindowsHookEx(13, hookproc, Marshal.GetHINSTANCE(Assembly.GetExecutingAssembly().GetModules()[0]), 0);
            }
            return (hKeyboardHook != 0);
        }

        // 卸载钩子   
        public bool Stop()
        {
            if (hKeyboardHook != 0)
            {
                return UnhookWindowsHookEx(hKeyboardHook);
            }
            return true;
        }
    }
}

2.在winform界面展示

3.给出界面应用的代码

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

namespace ScanDemo
{
    public partial class Form1 : Form
    {
        //钩子
        BarCodeHook BarCode = new BarCodeHook();
        public Form1()
        {
            BarCode.BarCodeEvent += new BarCodeHook.BarCodeDelegate(BarCode_BarCodeEvent);//扫码委托
            InitializeComponent();
        }
        private delegate void ShowInfoDelegate(BarCodeHook.BarCodes barCode);
        private void HandleBarCode(BarCodeHook.BarCodes barCode)
        {
            if (this.InvokeRequired)
            {
                this.BeginInvoke(new ShowInfoDelegate(HandleBarCode), new object[] { barCode });
            }
            else
            {

                if (barCode.IsValid)
                {
                    
                    this.label1.Text = Regex.Replace(barCode.BarCode, @"\s", "");//这里使用了一个正则，为了去掉里面的空格，制表符等无效字符
                }
            }
        }

        //钩子回调方法
        void BarCode_BarCodeEvent(BarCodeHook.BarCodes barCode)
        {
            HandleBarCode(barCode);
        }

        private void button1_Click(object sender, EventArgs e)
        {
            BarCode.Start();//钩子安装
        }

        private void button2_Click(object sender, EventArgs e)
        {
            BarCode.Stop();//钩子卸载
        }
    }
}

4.效果