样式一：
protected void Page_Load(object sender, EventArgs e)
{
if (!Page.IsPostBack)
{
this.GenImg(this.GenCode(4));
}
}
private string GenCode(int num)
{
string[] source ={"1","2","3","4","5","6","7","8","9",
"A","B","C","D","E","F","G","H","I","J","K","L","M","N",
"P","Q","R","S","T","U","V","W","X","Y","Z"};
string code = "";
Random rd = new Random();
for (int i = 0; i < num; i++)
{
code += source[rd.Next(0, source.Length)];
}
return code;
}
//生成图片
private void GenImg(string code)
{
Bitmap myPalette = new Bitmap(40, 18);
样式二：
protected void Page_Load(object sender, EventArgs e)
{
CreateCheckCodeImage(GenerateCheckCode());
}
//随机生成验证码
private string GenerateCheckCode()
{
int number;
char code;
string checkCode = String.Empty;
System.Random random = new Random();
for (int i = 0; i < 5; i++)
{
number = random.Next();
if (number % 2 == 0)
code = (char)('0' + (char)(number % 10));
else
code = (char)('A' + (char)(number % 26));
checkCode += code.ToString();
}
Response.Cookies.Add(new HttpCookie("CheckCode", checkCode));
return checkCode;
}
//生成验证码图片
private void CreateCheckCodeImage(string checkCode)
{
if (checkCode == null || checkCode.Trim() == String.Empty)
return;
System.Drawing.Bitmap image = new System.Drawing.Bitmap((int)Math.Ceiling((checkCode.Length * 12.5)), 22);
Graphics g = Graphics.FromImage(image);
try
{
Random random = new Random();
g.Clear(Color.White);
for (int i = 0; i < 25; 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);
g.DrawLine(new Pen(Color.Silver), x1, y1, x2, y2);
}
Font font = new System.Drawing.Font("Arial", 12, (System.Drawing.FontStyle.Bold | System.Drawing.FontStyle.Italic));
System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height), Color.Blue, Color.DarkRed, 1.2f, true);
g.DrawString(checkCode, font, brush, 2, 2);
for (int i = 0; i < 100; i++)
{
int x = random.Next(image.Width);
int y = random.Next(image.Height);
image.SetPixel(x, y, Color.FromArgb(random.Next()));
}
g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);
System.IO.MemoryStream ms = new System.IO.MemoryStream();
image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);
Response.ClearContent();
Response.ContentType = "image/Gif";
Response.BinaryWrite(ms.ToArray());
}
finally
{
g.Dispose();
image.Dispose();
}
}
样式三：
private static Random rnd = new Random();
protected void Page_Load(object sender, EventArgs e)
{
int width = 60;
int height = 20;
Bitmap img = new Bitmap(width, height);
Graphics g = Graphics.FromImage(img);
Brush b;
b = new SolidBrush(Color.FromArgb(rnd.Next(200, 250), rnd.Next(200, 250), rnd.Next(200, 250)));
g.FillRectangle(b, 0, 0, width, height);
Pen p = new Pen(Color.FromArgb(rnd.Next(160, 200), rnd.Next(160, 200), rnd.Next(160, 200)));
for (int i = 0; i < 100; i++)
{
int x1 = rnd.Next(width);
int y1 = rnd.Next(height);
int x2 = x1 + rnd.Next(12);
int y2 = y1 + rnd.Next(12);
g.DrawLine(p, x1, y1, x2, y2);
}
Font f = new Font("Courier New", 16, FontStyle.Bold);
PointF pf;
StringBuilder sb = new StringBuilder();
for (int i = 0; i < 4; i++)
{
string s = rnd.Next(10).ToString();
sb.Append(s);
b = new SolidBrush(Color.FromArgb(rnd.Next(20, 130), rnd.Next(20, 130), rnd.Next(20, 130)));
pf = new PointF(13 * i, -1);
g.DrawString(s, f, b, pf);
}
Session["Captcha"] = sb.ToString();
Response.ContentType = "image/pjpeg";
img.Save(Response.OutputStream, ImageFormat.Jpeg);
b.Dispose();
g.Dispose();
img.Dispose();
}
样式四：
protected void Page_Load(object sender, EventArgs e)
{
System.Random rand = new Random();
int len = rand.Next(4, 6);
char[] chars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ".ToCharArray();
System.Text.StringBuilder myStr = new System.Text.StringBuilder();
for (int iCount = 0; iCount < len; iCount++)
{
myStr.Append(chars[rand.Next(chars.Length)]);
}
string text = myStr.ToString();
this.Session["checkcode"] = text;
Size ImageSize = Size.Empty;
Font myFont = new Font("MS Sans Serif", 12);
using (Bitmap bmp = new Bitmap(10, 10))
{
using (Graphics g = Graphics.FromImage(bmp))
{
SizeF size = g.MeasureString(text, myFont, 5000);
ImageSize.Width = (int)size.Width + 1;
ImageSize.Height = (int)size.Height + 1;
}
}
using (Bitmap bmp = new Bitmap(ImageSize.Width, ImageSize.Height))
{
using (Graphics g = Graphics.FromImage(bmp))
{
g.Clear(Color.White);
using (StringFormat f = new StringFormat())
{
f.Alignment = StringAlignment.Near;
f.LineAlignment = StringAlignment.Center;
f.FormatFlags = StringFormatFlags.NoWrap;
g.DrawString(
text,
myFont,
Brushes.Black,
new RectangleF(
0,
0,
ImageSize.Width,
ImageSize.Height),
f);
}
}
int num = ImageSize.Width * ImageSize.Height * 30 / 100;
for (int iCount = 0; iCount < num; iCount++)
{
int x = rand.Next(ImageSize.Width);
int y = rand.Next(ImageSize.Height);
int r = rand.Next(255);
int g = rand.Next(255);
int b = rand.Next(255);
Color c = Color.FromArgb(r, g, b);
bmp.SetPixel(x, y, c);
}
System.IO.MemoryStream ms = new System.IO.MemoryStream();
bmp.Save(ms, System.Drawing.Imaging.ImageFormat.Png);
this.Response.ContentType = "image/png";
ms.WriteTo(this.Response.OutputStream);
ms.Close();
}
myFont.Dispose();
}
感谢http://www.cnblogs.com/baiyuntian/archive/2011/11/10/2244334.html