这篇文章给大家分享的是有关ASP.NET如何制作验证码的内容。小编觉得挺实用的，因此分享给大家做个参考，一起跟随小编过来看看吧。
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///
/// 验证码生成类
///
public class verify_code : IHttpHandler, IRequiresSessionState
{
public void ProcessRequest(HttpContext context)
{
int codeW = 80;
int codeH = 22;
int fontSize = 16;
string chkCode = string.Empty;
//颜色列表，用于验证码、噪线、噪点
Color[] color = { Color.Black, Color.Red, Color.Blue, Color.Green, Color.Orange, Color.Brown, Color.Brown, Color.DarkBlue };
//字体列表，用于验证码
string[] font = { "Times New Roman", "Verdana", "Arial", "Gungsuh", "Impact" };
//验证码的字符集，去掉了一些容易混淆的字符
char[] character = { '0', '1', '2', '3', '4', '5', '6', '8', '9' };
Random rnd = new Random();
//生成验证码字符串
for (int i = 0; i < 4; i++)
{
chkCode += character[rnd.Next(character.Length)];
}
//写入Session
context.Session["sys_verify_code"] = chkCode;
//创建画布
Bitmap bmp = new Bitmap(codeW, codeH);
Graphics g = Graphics.FromImage(bmp);
g.Clear(Color.White);
//画噪线
for (int i = 0; i < 4; i++)
{
int x1 = rnd.Next(codeW);
int y1 = rnd.Next(codeH);
int x2 = rnd.Next(codeW);
int y2 = rnd.Next(codeH);
Color clr = color[rnd.Next(color.Length)];
g.DrawLine(new Pen(clr), x1, y1, x2, y2);
}
//画验证码字符串
for (int i = 0; i < chkCode.Length; i++)
{
string fnt = font[rnd.Next(font.Length)];
Font ft = new Font(fnt, fontSize);
Color clr = color[rnd.Next(color.Length)];
g.DrawString(chkCode[i].ToString(), ft, new SolidBrush(clr), (float)i * 18 + 2, (float)0);
}
//画噪点
for (int i = 0; i < 100; i++)
{
int x = rnd.Next(bmp.Width);
int y = rnd.Next(bmp.Height);
Color clr = color[rnd.Next(color.Length)];
bmp.SetPixel(x, y, clr);
}
//清除该页输出缓存，设置该页无缓存
context.Response.Buffer = true;
context.Response.ExpiresAbsolute = System.DateTime.Now.AddMilliseconds(0);
context.Response.Expires = 0;
context.Response.CacheControl = "no-cache";
context.Response.AppendHeader("Pragma", "No-Cache");
//将验证码图片写入内存流，并将其以 "image/Png" 格式输出
MemoryStream ms = new MemoryStream();
try
{
bmp.Save(ms, ImageFormat.Png);
context.Response.ClearContent();
context.Response.ContentType = "image/Png";
context.Response.BinaryWrite(ms.ToArray());
}
finally
{
//显式释放资源
bmp.Dispose();
g.Dispose();
}
}
public bool IsReusable
{
get
{
return false;
}
}
}
基本验证生成代码demo：
using System;
using System.Drawing;
using System.Drawing.Imaging;
using System.IO;
using System.Web;
public partial class image : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
string tmp = RndNum(4);
HttpCookie a = new HttpCookie("ImageV", tmp);
Response.Cookies.Add(a);
this.ValidateCode(tmp);
}
private void ValidateCode(string VNum)
{
Bitmap Img = null;
Graphics g = null;
MemoryStream ms = null;
int gheight = VNum.Length * 12;
Img = new Bitmap(gheight, 25);
g = Graphics.FromImage(Img);
//背景颜色
g.Clear(Color.White);
//文字字体
Font f = new Font("Arial Black", 10);
//文字颜色
SolidBrush s = new SolidBrush(Color.Black);
g.DrawString(VNum, f, s, 3, 3);
ms = new MemoryStream();
Img.Save(ms, ImageFormat.Jpeg);
Response.ClearContent();
Response.ContentType = "image/Jpeg";
Response.BinaryWrite(ms.ToArray());
g.Dispose();
Img.Dispose();
Response.End();
}
private string RndNum(int VcodeNum)
{
string Vchar = "0,1,2,3,4,5,6,7,8,9,a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p" +
",q,r,s,t,u,v,w,x,y,z";
string[] VcArray = Vchar.Split(new Char[] { ',' });
string VNum = "";
int temp = -1;
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(35);
if (temp != -1 && temp == t)
{
return RndNum(VcodeNum);
}
temp = t;
VNum += VcArray[t];
}
return VNum;
}
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