我们在设计用户登录模块时，经常会用到验证码，可以有效地防止黑客软件的恶意破解，现公开我常用的验证码的源代码，生成效果如图：
<IMG src="/upfiles/2007-4/20074158492434613.jpg" border=0
使用方法：
1、在Web项目中添加一个类，如“CreateImage.cs”，然后将我公布的源代码Copy进去；
2、再新建一个Web窗体，如“Image.aspx”，在Page_Load中加入代码 “CreateImage.DrawImage ();”当然别忘了加上对类的引用哦！！
3、在页面的合适位置上（你想放验证码的位置）上加上如下javascript代码就OK 了，
<script language=”JavaScript”>
var numkey = Math.random();
numkey = Math.round(numkey*10000);
document.write(“<img src=\\”Image.aspx?k=”+ numkey +”\\” width=\\”52\\” height=\\”23\\” hspace=\\”4\\”");
</script>
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源代码如下：
复制C#代码保存代码///
/// 验证码模块
///
public class CreateImage
{
public static void DrawImage()
{
CreateImage img = new CreateImage();
HttpContext.Current.Session["CheckCode"] = img.RndNum(4);
img.CreateImages(HttpContext.Current.Session["CheckCode"].ToString());
}
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///
/// 生成验证图片
///
/// 验证字符
private void CreateImages(string checkCode)
{
int iwidth = (int) (checkCode.Length * 13);
System.Drawing.Bitmap image = new System.Drawing.Bitmap(iwidth, 23);
Graphics g = Graphics.FromImage(image);
g.Clear(Color.White);
//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” };
Random rand = new Random();
//随机输出噪点
for (int i = 0; i < 50; i++)
{
int x = rand.Next(image.Width);
int y = rand.Next(image.Height);
g.DrawRectangle(new Pen(Color.LightGray, 0), x, y, 1, 1);
}
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//输出不同字体和颜色的验证码字符
for (int i = 0; i < checkCode.Length; i++)
{
int cindex = rand.Next(7);
int findex = rand.Next(5);
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Font f = new System.Drawing.Font(font[findex], 10, System.Drawing.FontStyle.Bold);
Brush b = new System.Drawing.SolidBrush(c[cindex]);
int ii = 4;
if ((i + 1) % 2 == 0)
{
ii = 2;
}
g.DrawString(checkCode.Substring(i, 1), f, b, 3 + (i * 12), ii);
}
//画一个边框
g.DrawRectangle(new Pen(Color.Black, 0), 0, 0, image.Width – 1, image.Height – 1);
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//输出到浏览器
System.IO.MemoryStream ms = new System.IO.MemoryStream();
image.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
HttpContext.Current.Response.ClearContent();
//Response.ClearContent();
HttpContext.Current.Response.ContentType = “image/Jpeg”;
HttpContext.Current.Response.BinaryWrite(ms.ToArray());
g.Dispose();
image.Dispose();
}
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///
/// 生成随机的字母
///
/// 生成字母的个数
/// string
private string RndNum(int VcodeNum)
{
string Vchar = “0,1,2,3,4,5,6,7,8,9″;
string[] VcArray = Vchar.Split(‘,’);
string VNum = “”; //由于字符串很短，就不用StringBuilder了
int temp = -1; //记录上次随机数值，尽量避免生产几个一样的随机数
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//采用一个简单的算法以保证生成随机数的不同
Random rand = new Random();
for (int i = 1; i < VcodeNum + 1; i++)
{
if (temp != -1)
{
rand = new Random(i * temp * unchecked((int) DateTime.Now.Ticks));
}
int t = rand.Next(VcArray.Length);
if (temp != -1 && temp == t)
{
return RndNum(VcodeNum);
}
temp = t;
VNum += VcArray[t];
}
return VNum;
}
}
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附件: AspNetCheckCodeExample.rar
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来源: 阿良.NET