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3年前写了一篇《USB口的红外条形码扫描器的另类使用》，不过相关代码是VB编写，在这几年之间，有许多网友提出需要C#版的，起初还以为由VB修改C#应该很容易，最近研究了一下，发现C#和VB调用API的机制还是有所不同的，在迁移的过程中还是会遇到不少问题，所以我专门抽时间做了一个基于C#的程序。
【目前的条形码扫描器有点类似外接键盘（其实从消息传送上它就相当于一个键盘），把输入焦点定位到可输入的控件上，一扫描相应的条形码信息就输入到文本框中去了，但是如果没有输入焦点，或另一个不相干的程序获得输入焦点，那就有点乱套了。我想实现的是，不管什么情况，只要扫描器一工作，我的程序就能自动激活，并能获得当前输入的条形码信息。 实现思路：我用的是litele牌的USB口的红外条形码扫描器，仔细分析了一下，扫描成功后，以键盘按键消息的形式把条形码输入信息通知给系统。这样通过键盘钩子就可以方便的获得该信息了。但是，怎样区分信息是键盘还是条形码输入的哪？很简单，条形码扫描器在很短的时间内输入了至少3个字符以上信息，并且以“回车”作为结束字符，在这种思想指引下，很完美的实现了预定功能。】
VB相关的代码请见：http://blog.csdn.net/yefanqiu/archive/2006/08/30/1144881.aspx
窗体相关代码：
- using System;
- using System.Collections.Generic;
- using System.ComponentModel;
- using System.Data;
- using System.Drawing;
- using System.Text;
- using System.Windows.Forms;
- namespace ReadBadCode
- {
- public partial class frmTest : Form
- {
- BarCodeHook BarCode = new BarCodeHook();
- public frmTest()
- {
- InitializeComponent();
- BarCode.BarCodeEvent += new BarCodeHook.BarCodeDelegate(BarCode_BarCodeEvent);
- }
- private delegate void ShowInfoDelegate(BarCodeHook.BarCodes barCode);
- private void ShowInfo(BarCodeHook.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.AscII.ToString();
- textBox5.Text = barCode.Chr.ToString();
- textBox6.Text = barCode.IsValid ? barCode.BarCode : "";
- }
- }
- void BarCode_BarCodeEvent(BarCodeHook.BarCodes barCode)
- {
- ShowInfo(barCode);
- }
- private void frmTest_Load(object sender, EventArgs e)
- {
- BarCode.Start();
- }
- private void frmTest_FormClosed(object sender, FormClosedEventArgs e)
- {
- BarCode.Stop();
- }
- private void textBox6_TextChanged(object sender, EventArgs e)
- {
- if (textBox6.Text.Length > 0)
- {
- MessageBox.Show(textBox6.Text);
- }
- }
- }
- }
BarCodeHook 类：
- using System;
- using System.Collections.Generic;
- using System.Text;
- using System.Runtime.InteropServices;
- using System.Reflection;
- namespace ReadBadCode
- {
- public 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 KeyName; //键名
- public uint AscII; //AscII
- public char Chr; //字符
- 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
- {
- 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 lParam, 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[] lpKeyState, ref uint lpChar, int uFlags);
- delegate int HookProc(int nCode, Int32 wParam, IntPtr lParam);
- BarCodes barCode = new BarCodes();
- int hKeyboardHook = 0;
- string strBarCode = "";
- 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
- StringBuilder strKeyName = new StringBuilder(255);
- 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.AscII = uKey;
- barCode.Chr = Convert.ToChar(uKey);
- }
- if (DateTime.Now.Subtract(barCode.Time).TotalMilliseconds > 50)
- {
- strBarCode = barCode.Chr.ToString();
- }
- else
- {
- if ((msg.message & 0xff) == 13 && strBarCode.Length > 3) //回车
- {
- barCode.BarCode = strBarCode;
- barCode.IsValid = true;
- }
- strBarCode += barCode.Chr.ToString();
- }
- barCode.Time = DateTime.Now;
- if (BarCodeEvent != null) BarCodeEvent(barCode); //触发事件
- barCode.IsValid = false;
- }
- }
- return CallNextHookEx(hKeyboardHook, nCode, wParam, lParam);
- }
- // 安装钩子
- public bool Start()
- {
- if (hKeyboardHook == 0)
- {
- //WH_KEYBOARD_LL = 13
- hKeyboardHook = SetWindowsHookEx(13, new HookProc(KeyboardHookProc), 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;
- }
- }
- }
【注意】和VB程序不同，要想测试实际的效果，必须执行编译后的Exe文件，在开发环境直接运行会没有效果的。
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