我们经常在网络上能看到一些网站需要输入验证码进行验证，下面这段源码供大家参考：
public class CheckCode
{
public static void DeawImage()
{
CheckCode img = new CheckCode();
HttpContext.Current.Session["CheckCode"] = img.RandNum(5);
img.checkCodes(HttpContext.Current.Session["CheckCode"].ToString());
}
private void checkCodes(string checkcode)
{
int iwidth = (int)(checkcode.Length * 15);
System.Drawing.Bitmap image = new System.Drawing.Bitmap(iwidth,30);
System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(image);
g.Clear(System.Drawing.Color.White);
System.Drawing.Color[] color = {Color.Black,Color.Red,Color.Blue,Color.DarkBlue,Color.Green,Color.Orange,Color.Brown,Color.DarkCyan,Color.Purple };
string[] font = {"小篆","楷书","黑体","幼圆","宋体" };
Random rand = new Random();
//随机噪点
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);
}
//输出不同字体颜色的字符
for (int i = 0; i < checkcode.Length; i++)
{
int cindex = rand.Next(color.Count());
int findex = rand.Next(font.Count());
Font f = new Font(font[findex],15,FontStyle.Italic);
Brush b = new SolidBrush(color[cindex]);
int ii = 5;
if ((i + 1) % 2 == 0)
{
ii = 2;
}
g.DrawString(checkcode.Substring(i,1),f,b,3+(i*10),ii);
}
g.DrawRectangle(new Pen(Color.Black,0),0,0,image.Width-1,image.Height-1);
System.IO.MemoryStream ms = new System.IO.MemoryStream();
image.Save(ms,System.Drawing.Imaging.ImageFormat.Jpeg);
HttpContext.Current.Response.ClearContent();
HttpContext.Current.Response.ContentType = "image/Jpeg";
HttpContext.Current.Response.BinaryWrite(ms.ToArray());
g.Dispose();
image.Dispose();
}
//随即字符
private string RandNum(int num)
{
string strcode = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
string code = "";
Random rand = new Random();
for (int i = 0; i < num; i++)
{
code += strcode.Substring(rand.Next(0, strcode.Length), 1);
}
return code;
}
}