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验证码程序
验证码的一般编写思路为：
1.定义验证码字符长度;
2.根据长度随机生成验证码字符串;
3.将验证码字符串转换成图片形式，并在图片中生成随机噪声点和声线（对验证码进行模糊识别处理）;
4.显示结果。
///
/// 生成随机验证码
///
/// 验证码长度
///
public string CreateIdentifyingCode(int CodeLen)
{
if (CodeLen < 1)
return String.Empty;
int num;
string checkcode = String.Empty;
Random random = new Random();
for (int index = 0; index < CodeLen; index++)
{
num = random.Next();
if (num % 2 == 0)
checkcode += (char)(‘0‘ + (char)(num % 10));
else
checkcode += (char)(‘A‘ + (char)(num % 26));
}
return checkcode;
}
-------------------------------------------------------------------------------------------------
///
/// 生成验证码图片
///
///
///
private void CreateCheckCodeImage(string checkcode)
{
if (checkcode == null || checkcode.Trim() == String.Empty)
return;
//创建图片大小
System.Drawing.Bitmap image = new System.Drawing.Bitmap((int)Math.Ceiling(checkcode.Length*12.5),22);
//创建画板
Graphics graphic = Graphics.FromImage(image);
try
{
Random random = new Random();
graphic.Clear(Color.White);
int x1 = 0, y1 = 0, x2 = 0, y2 = 0;
//画图片背景噪声线
for (int index = 0; index < 25; index++)
{
x1 = random.Next(image.Width);
y1 = random.Next(image.Height);
x2 = random.Next(image.Width);
y2 = random.Next(image.Height);
graphic.DrawLine(new Pen(Color.Silver),x1,y1,x2,y2);
}
Font font = new System.Drawing.Font("Helvetica", 12, (FontStyle.Bold |FontStyle.Italic));
LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height),Color.Blue,Color.DarkBlue,1.2f,true);
graphic.DrawString(checkcode,font,brush,2,2);
int x = 0;
int y = 0;
// 画图片的前景噪声点
for (int index = 0; index < 100; index++)
{
x = random.Next(image.Width);
y = random.Next(image.Height);
image.SetPixel(x,y,Color.FromArgb(random.Next()));
}
//画图片的边框线
graphic.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);
//网页响应
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
{
graphic.Dispose();
image.Dispose();
}
}
以上所生成的为简单的验证码。接下来我从其他的博客中学习了其他形式的效果。
/* 图片画线特殊效果：贝塞尔曲线 */
Graphics graph = Graphics.FromImage(image);
graph.Clear(Color.WhiteSmoke);
Point[] myArray ={
new Point(random.Next(150),random.Next(50)),
new Point(random.Next(150),random.Next(50)),
new Point(random.Next(150),random.Next(50)),
new Point(random.Next(150),random.Next(50)),
new Point(random.Next(150),random.Next(50)),
new Point(random.Next(150),random.Next(50)),
new Point(random.Next(150),random.Next(50)),
new Point(random.Next(150),random.Next(50)),
new Point(random.Next(150),random.Next(50)),
new Point(random.Next(150),random.Next(50))
};
Pen myPen = new Pen(Color.Blue, 1);
GraphicsPath myPath = new GraphicsPath();
myPath.AddBeziers(myArray);
graph.DrawPath(myPen, myPath);
验证码字符颜色变换效果：实现该效果，我们首先来定义一个颜色集合，然后通过for循环使其随机改变字体颜色则可。
#region 定义颜色数组
Color[] colors = { Color.Blue, Color.Green, Color.Red, Color.Gold, Color.Black, Color.Chocolate, Color.Orange, Color.Purple };
public Color[] Colors
{
get { return colors; }
set { colors = value; }
}
#endregion
Brush brush;
int colornum;
for(int i=0; i
{
colornum = random.Next(Colors.Length - 1);
brush = new System.Drawing.SolidBrush(Colors[cindex]);
//利用DrawString函数进行颜色填充就可以了。
}
同样的原理我们也可以定义一个字体的数组来进行验证码字体切换。代码和颜色的类似，这里就不加以累赘。
接下来看看如何使得验证码的字体进行扭曲。这里的代码是从http://blog.sina.com.cn/s/blog_5d71453e0100y5t5.html学习的
private const double PI = 3.1415926535897932384626433832795;
private const double PI2 = 6.283185307179586476925286766559;
///
/// 波形滤镜效果函数
///
///
///
///
///
///
public System.Drawing.Bitmap TwistImage(Bitmap srcbmp, double dmultvalue, double dphase)
{
System.Drawing.Bitmap destbmp = new Bitmap(srcbmp.Width,srcbmp.Height);
System.Drawing.Graphics graph = System.Drawing.Graphics.FromImage(destbmp);
//填充背景图为白色
graph.FillRectangle(new SolidBrush(System.Drawing.Color.White), 0, 0, destbmp.Width, destbmp.Height);
graph.Dispose();
double dbaselen = (double)destbmp.Width;
for (int i = 0; i < destbmp.Width; i++)
{
for (int j = 0; j < destbmp.Height; j++)
{
double dx = 0;
dx = (PI2 * (double)j) / dbaselen;
dx += dphase;
double dy = Math.Sin(dx);
int noldx = 0, noldy = 0;
noldx = i + (int)(dy * dmultvalue);
noldy = j + (int)(dy * dmultvalue);
System.Drawing.Color color = srcbmp.GetPixel(i, j);
if (noldx >= 0 && noldx < destbmp.Width && noldy >= 0 && noldy < destbmp.Height)
destbmp.SetPixel(noldx, noldy, color);
}
}
return destbmp;
}
验证码程序
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