C# WinForm 登录界面的图片验证码(区分大小写+不区
一、功能界面
图1 验证码(区分大小写)
二、创建一个产生验证码的类Class1
（1）生成随机验证码字符串，用的是Random随机函数
（2）创建验证码图片，将该字符串画在PictureBox控件中
Class1.cs：
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Drawing;//图片
using System.Windows.Forms;
namespace ValidCodeTest
{
public class Class1
{
#region 验证码功能
/// <summary>
/// 生成随机验证码字符串
/// </summary>
public static string CreateRandomCode(int CodeLength)
{
int rand;
char code;
string randomCode = String.Empty;//随机验证码
//生成一定长度的随机验证码
//Random random = new Random();//生成随机数对象
for (int i = 0; i < CodeLength; i++)
{
//利用GUID生成6位随机数
byte[] buffer = Guid.NewGuid().ToByteArray();//生成字节数组
int seed = BitConverter.ToInt32(buffer, 0);//利用BitConvert方法把字节数组转换为整数
Random random = new Random(seed);//以生成的整数作为随机种子
rand = random.Next();
//rand = random.Next();
if (rand % 3 == 1)
{
code = (char)('A' + (char)(rand % 26));
}
else if (rand % 3 == 2)
{
code = (char)('a' + (char)(rand % 26));
}
else
{
code = (char)('0' + (char)(rand % 10));
}
randomCode += code.ToString();
}
return randomCode;
}
/// <summary>
/// 创建验证码图片
/// </summary>
public static void CreateImage(string strValidCode, PictureBox pbox)
{
try
{
int RandAngle = 45;//随机转动角度
int MapWidth = (int)(strValidCode.Length * 21);
Bitmap map = new Bitmap(MapWidth, 28);//验证码图片—长和宽
//创建绘图对象Graphics
Graphics graph = Graphics.FromImage(map);
graph.Clear(Color.AliceBlue);//清除绘画面,填充背景色
graph.DrawRectangle(new Pen(Color.Black, 0), 0, 0, map.Width - 1, map.Height - 1);//画一个边框
graph.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias;//模式
Random rand = new Random();
//背景噪点生成
Pen blackPen = new Pen(Color.LightGray, 0);
for (int i = 0; i < 50; i++)
{
int x = rand.Next(0, map.Width);
int y = rand.Next(0, map.Height);
graph.DrawRectangle(blackPen, x, y, 1, 1);
}
//验证码旋转，防止机器识别
char[] chars = strValidCode.ToCharArray();//拆散字符串成单字符数组
//文字居中
StringFormat format = new StringFormat(StringFormatFlags.NoClip);
format.Alignment = StringAlignment.Center;
format.LineAlignment = StringAlignment.Center;
//定义颜色
Color[] c = { Color.Black, Color.Red, Color.DarkBlue, Color.Green, Color.Orange, Color.Brown, Color.DarkCyan, Color.Purple };
//定义字体
string[] font = { "Verdana", "Microsoft Sans Serif", "Comic Sans MS", "Arial", "宋体" };
for (int i = 0; i < chars.Length; i++)
{
int cindex = rand.Next(7);
int findex = rand.Next(5);
Font f = new System.Drawing.Font(font[findex], 13, System.Drawing.FontStyle.Bold);//字体样式(参数2为字体大小)
Brush b = new System.Drawing.SolidBrush(c[cindex]);
Point dot = new Point(16, 16);
float angle = rand.Next(-RandAngle, RandAngle);//转动的度数
graph.TranslateTransform(dot.X, dot.Y);//移动光标到指定位置
graph.RotateTransform(angle);
graph.DrawString(chars[i].ToString(), f, b, 1, 1, format);
graph.RotateTransform(-a【原URL http://www.yidunidc.com/mggfzq.html 请说明出处】ngle);//转回去
graph.TranslateTransform(2, -dot.Y);//移动光标到指定位置
}
pbox.Image = map;
}
catch (ArgumentException)
{
MessageBox.Show("验证码图片创建错误");
}
}
#endregion
}
}
三、调用
（1）更新验证码
（2）验证（区分大小写）
（3）验证（不区分大小写）
Form1.cs：
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;
using ValidCodeTest;
namespace ValidCode
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
#region 验证码
private const int ValidCodeLength = 4;//验证码长度
private String strValidCode = "";//验证码
//调用自定义函数,更新验证码
private void UpdateValidCode()
{
strValidCode = Class1.CreateRandomCode(ValidCodeLength);//生成随机验证码
if (strValidCode == "") return;
Class1.CreateImage(strValidCode, pbox1);//创建验证码图片
}
#endregion
private void pbox1_Click(object sender, EventArgs e)
{
UpdateValidCode();//点击更新验证码
}
private void Form1_Load(object sender, EventArgs e)
{
UpdateValidCode();//加载更新验证码
}
/// <summary>
/// 验证（区分大小写）
/// </summary>
private void btn1_Click(object sender, EventArgs e)
{
string validcode = txtValidCode.Text.Trim();
char[] ch1 = validcode.ToCharArray();
char[] ch2 = strValidCode.ToCharArray();
int Count1 = 0;//字母个数
int Count2 = 0;//数字个数
if (String.IsNullOrEmpty(validcode) != true)//验证码不为空
{
for (int i = 0; i < strValidCode.Length; i++)
{
if ((ch1[i] >= 'a' && ch1[i] <= 'z') || (ch1[i] >= 'A' && ch1[i] <= 'Z'))//字母
{
if (ch1[i] == ch2[i])
{
Count1++;
}
}
else//数字
{
if (ch1[i] == ch2[i])
{
Count2++;
}
}
}
int CountSum = Count1 + Count2;
if (CountSum == strValidCode.Length)
{
MessageBox.Show("验证通过", "提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
UpdateValidCode();
txtValidCode.Text = "";
txtValidCode.Focus();
}
else
{
MessageBox.Show("验证失败", "警告", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
UpdateValidCode();//更新验证码
txtValidCode.Text = "";
txtValidCode.Focus();
}
}
else//验证码为空
{
MessageBox.Show("请输入验证码", "提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
UpdateValidCode();//更新验证码
txtValidCode.Text = "";
txtValidCode.Focus();
}
}
/// <summary>
/// 验证（不区分大小写）
/// </summary>
private void btn2_Click(object sender, EventArgs e)
{
string validcode = txtValidCode.Text.Trim();
if (String.IsNullOrEmpty(validcode) != true)//验证码不为空
{
if (validcode.ToLower() == strValidCode.ToLower())
{
MessageBox.Show("验证通过", "提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
UpdateValidCode();
txtValidCode.Text = "";
txtValidCode.Focus();
}
else
{
MessageBox.Show("验证失败", "警告", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
UpdateValidCode();//更新验证码
txtValidCode.Text = "";
txtValidCode.Focus();
}
}
else//验证码为空
{
MessageBox.Show("请输入验证码", "提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
UpdateValidCode();//更新验证码
txtValidCode.Text = "";
txtValidCode.Focus();
}
}
}
}
.exe测试文件下载: ValidCode_jb51.zip
参考文章：
https://www.jianshu.com/p/d89f22cf51bf
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