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using System.Drawing;
protected void FormCheck()
{
//////先得到验证码的内容并且存放到会话中
Random rand = new Random();
int len = rand.Next(4, 6);//随机获得验证码的长度4-6位
char[] str = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ".ToCharArray();//将候选字符放入字符数组中
System .Text .StringBuilder code=new System.Text.StringBuilder ();//用来保存显示的字符内容
for (int i=0;i<len;i++)
{
code .Append (str [rand .Next (str.Length )]);
}
this.Session ["result"]=code.ToString () ;//将验证码存放到会话中
///////得到图像的大小
Size imageSize = new Size();
Font myFont = new Font("arial black", 20); //字体
using (Bitmap bmp = new Bitmap(20, 15))
{ using (Graphics g=Graphics .FromImage (bmp ))
{
SizeF size=g.MeasureString (code.ToString () ,myFont,1000 );
imageSize .Width =(int)size .Width +6;//得到高度和宽的
imageSize .Height =(int)size .Height +5;
}
}
/////创建验证码的图像
using (Bitmap bmp=new Bitmap (imageSize .Width ,imageSize .Height ))
{
using (Graphics g=Graphics .FromImage (bmp ))
{
g.Clear(Color .White );
g.DrawString (code.ToString () ,myFont ,Brushes .Black ,new RectangleF (0,0,imageSize.Width ,imageSize .Height ));
}
int num = imageSize.Width * imageSize.Height * 30 / 100;
for (int iCount = 0; iCount < num; iCount++)
{
// 在随机的位置使用随机的颜色设置图片的像素
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);
}//for // 输出图片
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();
}
}
/// /// 检查指定的文本是否匹配验证码 /// /// 要判断的文本 /// 是否匹配 public static bool CheckCode( string text ) { string txt = System.Web.HttpContext.Current.Session["checkcode"] as string ; return text == txt ; }
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