Winform实现验证码功能

介绍下Winform实现验证码的步骤：

首先拖入控件：PictureBox显示验证码；TextBox输入验证码；Check按钮；Label标签-点击更换验证码；

1.随机产生一个4位的字符串，由数字，大小写字母组成：

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string RandomCode() {     string retCode = "";     for (int i = 0; i < 4; i++)     {         while (true)         {             int id = rd.Next(48, 122);             if (id >= 48 && id <= 57 || id >= 65 && id <= 90 || id >= 97 && id <= 122)             {                 retCode += Convert.ToChar(id).ToString();                 break;             }         }     }     return retCode; }

2.创建画板：

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Bitmap bMap = new Bitmap(this.pictureBox1.Width,this.pictureBox1.Height); Graphics g = Graphics.FromImage(bMap); g.Clear(Color.LightGray);

3.在画板上画几条颜色随机的线条：

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for (int i = 0; i < 8; i++) {     int x1 = rd.Next(bMap.Width);     int y1 = rd.Next(bMap.Height);     int x2 = rd.Next(bMap.Width);     int y2 = rd.Next(bMap.Height);     g.DrawLine(new Pen(Color.FromArgb(rd.Next())), x1, y1, x2, y2); }

4.画一些背景噪点，颜色随机：

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for (int i = 0; i < 600; i++) {     int x = rd.Next(this.pictureBox1.Width);     int y = rd.Next(this.pictureBox1.Height);     bMap.SetPixel(x, y, Color.FromArgb(rd.Next())); }

5.画验证码：

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Font ft = new Font("宋体", 24, FontStyle.Bold | FontStyle.Italic); System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush(     new Rectangle(0, 0, bMap.Width, bMap.Height), Color.OrangeRed, Color.DarkOrchid, 1.2f, true); for (int i = 0; i < codeStr.Length; i++) {     g.DrawString(codeStr[i].ToString(), ft, brush, 5 + 23 * i, -1); }

6.将画好的图像赋给PictureBox:

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this.pictureBox1.Image = bMap; g.Dispose(); ft.Dispose();

7.按钮点击事件：

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private void Form1_Load(object sender, EventArgs e) {     rd = new Random();     CreateCodeImage(checkCode = RandomCode()); }   private void label1_Click(object sender, EventArgs e) {     CreateCodeImage(checkCode = RandomCode()); }   private void button1_Click(object sender, EventArgs e) {     if (textBox1.Text != checkCode)     {         MessageBox.Show("验证失败，请重新输入", "提示");         CreateCodeImage(checkCode = RandomCode());     }     else         MessageBox.Show("验证通过", "提示"); }

x效果展示：