实现代码
/// <summary>
/// 生成验证码图片
/// </summary>
/// <param name="code"></param>
/// <returns></returns>
public byte[] GenerateImg(string code)
{
Bitmap image = new Bitmap(code.Length * 25, 25);
Graphics g = Graphics.FromImage(image);
try
{
//清空图片背景色
g.Clear(Color.White);
//增加背景干扰线
Random random = new Random();
for (int i = 0; i < 30; i++)
{
int x1 = random.Next(image.Width);
int x2 = random.Next(image.Width);
int y1 = random.Next(image.Height);
int y2 = random.Next(image.Height);
//颜色可自定义
g.DrawLine(new Pen(Color.FromArgb(186, 212, 231)), x1, y1, x2, y2);
}
//定义验证码字体
Font font = new Font("黑体", 12, (FontStyle.Bold | FontStyle.Italic));
//定义验证码的刷子，这里采用渐变的方式，颜色可自定义
LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height), Color.FromArgb(67, 93, 230), Color.FromArgb(70, 128, 228), 1.5f, true);
//增加干扰点
for (int i = 0; i < 100; i++)
{
int x = random.Next(image.Width);
int y = random.Next(image.Height);
//颜色可自定义
image.SetPixel(x, y, Color.FromArgb(random.Next()));
}
//将验证码写入图片
g.DrawString(code, font, brush, random.Next(5, 50), random.Next(5, 10));
//图片边框
g.DrawRectangle(new Pen(Color.FromArgb(93, 142, 228)), 0, 0, image.Width - 1, image.Height - 1);
//保存图片数据
MemoryStream stream = new MemoryStream();
image.Save(stream, ImageFormat.Jpeg);
return stream.ToArray();
}
finally
{
g.Dispose();
image.Dispose();
}
}
private void button1_Click(object sender, EventArgs e)
{
GenerateCode();
}
private void GenerateCode()
{
string[] symbols = new string[]{
"+","-","*"
};
Random random = new Random();
string code = random.Next(0, 99) + symbols[random.Next(0,symbols.Length)] + random.Next(0, 99);
//这里拿到结果用来验证
DataTable dt = new DataTable();
string result = Convert.ToString(dt.Compute(code, null));
label1.Text = result;
byte[] bytes = GenerateImg(code);
MemoryStream ms = new MemoryStream(bytes);
Image image = System.Drawing.Image.FromStream(ms);
pictureBox1.Image = image;
}
代码解析：利用随机数分别取0到99的数字，然后做加减乘（为啥没除法？懒！因为还得算整除。），背景干扰什么的之前写过，此处不赘述。如果说你想考验下用户什么的，可以自己整个难度高一点的公式，比如：1+2*3之类的，反正直接让datatable去计算结果就行。。
