C# 红外条码扫描器的另类使用

来源：互联网发布：智慧城市与云计算编辑：程序博客网时间：2024/04/20 10:06

转载自：http://blog.csdn.net/yefanqiu/article/details/4146580

【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：

[c-sharp] view plaincopy

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：

[c-sharp] view plaincopy

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。