红外条码扫描器的另类使用C#版

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。】

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。

C# Winform中无焦点状态下获取键盘输入或者USB扫描枪数据

类文件：
1 using System;
2 using System.Collections.Generic;
3 using System.Text;
4 using System.Runtime.InteropServices;
5 using System.Reflection;
6
7 namespace Common
8 {
9 public class BardCodeHooK
10 {
11 public delegate void BardCodeDeletegate(BarCodes barCode);
12 public event BardCodeDeletegate BarCodeEvent;
13
14 public struct BarCodes
15 {
16 public int VirtKey;//虚拟吗
17 public int ScanCode;//扫描码
18 public string KeyName;//键名
19 public uint Ascll;//Ascll
20 public char Chr;//字符
21
22 public string BarCode;//条码信息
23 public bool IsValid;//条码是否有效
24 public DateTime Time;//扫描时间
25 }
26
27 private struct EventMsg
28 {
29 public int message;
30 public int paramL;
31 public int paramH;
32 public int Time;
33 public int hwnd;
34 }
35
36 [DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
37 private static extern int SetWindowsHookEx(int idHook, HookProc lpfn, IntPtr hInstance, int threadId);
38
39 [DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
40 private static extern bool UnhookWindowsHookEx(int idHook);
41
42 [DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
43 private static extern int CallNextHookEx(int idHook, int nCode, Int32 wParam, IntPtr lParam);
44
45 [DllImport("user32", EntryPoint = "GetKeyNameText")]
46 private static extern int GetKeyNameText(int IParam, StringBuilder lpBuffer, int nSize);
47
48 [DllImport("user32", EntryPoint = "GetKeyboardState")]
49 private static extern int GetKeyboardState(byte[] pbKeyState);
50
51 [DllImport("user32", EntryPoint = "ToAscii")]
52 private static extern bool ToAscii(int VirtualKey, int ScanCode, byte[] lpKeySate, ref uint lpChar, int uFlags);
53
54 delegate int HookProc(int nCode, Int32 wParam, IntPtr lParam);
55 BarCodes barCode = new BarCodes();
56 int hKeyboardHook = 0;
57 string strBarCode = "";
58
59 private int KeyboardHookProc(int nCode, Int32 wParam, IntPtr lParam)
60 {
61 if (nCode == 0)
62 {
63 EventMsg msg = (EventMsg)Marshal.PtrToStructure(lParam, typeof(EventMsg));
64 if (wParam == 0x100)//WM_KEYDOWN=0x100
65 {
66 barCode.VirtKey = msg.message & 0xff;//虚拟吗
67 barCode.ScanCode = msg.paramL & 0xff;//扫描码
68 StringBuilder strKeyName = new StringBuilder(225);
69 if (GetKeyNameText(barCode.ScanCode * 65536, strKeyName, 255) > 0)
70 {
71 barCode.KeyName = strKeyName.ToString().Trim(new char[] { ' ', '' });
72 }
73 else
74 {
75 barCode.KeyName = "";
76 }
77 byte[] kbArray = new byte[256];
78 uint uKey = 0;
79 GetKeyboardState(kbArray);
80
81
82 if (ToAscii(barCode.VirtKey, barCode.ScanCode, kbArray, ref uKey, 0))
83 {
84 barCode.Ascll = uKey;
85 barCode.Chr = Convert.ToChar(uKey);
86 }
87
88 TimeSpan ts = DateTime.Now.Subtract(barCode.Time);
89
90 if (ts.TotalMilliseconds > 50)
91 {
92 strBarCode = barCode.Chr.ToString();
93 }
94 else
95 {
96 if ((msg.message & 0xff) == 13 && strBarCode.Length > 3)
97 {
98 barCode.BarCode = strBarCode;
99 barCode.IsValid = true;
100 }
101 strBarCode += barCode.Chr.ToString();
102 }
103 barCode.Time = DateTime.Now;
104 if (BarCodeEvent != null) BarCodeEvent(barCode);//触发事件
105 barCode.IsValid = false;
106 }
107 }
108 return CallNextHookEx(hKeyboardHook, nCode, wParam, lParam);
109 }
110
111 //安装钩子
112 public bool Start()
113 {
114 if (hKeyboardHook == 0)
115 {
116 //WH_KEYBOARD_LL=13
117 hKeyboardHook = SetWindowsHookEx(13, new HookProc(KeyboardHookProc), Marshal.GetHINSTANCE(Assembly.GetExecutingAssembly().GetModules()[0]), 0);
118 }
119 return (hKeyboardHook != 0);
120 }
121
122 //卸载钩子
123 public bool Stop()
124 {
125 if (hKeyboardHook != 0)
126 {
127 return UnhookWindowsHookEx(hKeyboardHook);
128 }
129 return true;
130 }
131 }
132 }

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 + " 条码内容：" + textBox6.Text, "系统提示");
}
}
}
}