C#生成随机验证码例子：
前端：
<tr>
<td width="24%" height="" align="center" valign="top">
验证码：</td>
<td valign="top" width="37%" align="left">
<input type="text" name="txtCode" id="txtvalidateCode"/><a href="javascript:void(0)" id="valiateCode"><img src="/ashx/ValidateCode.ashx?id=1" id="imgCode" /></a><span style="font-size:14px;color:red " id="userCodeMsg"></span></td>
</tr>
给验证码图片绑定单击事件：
$("#valiateCode").click(function () {
$("#imgCode").attr("src",$("#imgCode").attr("src")+1);
});
后台生成验证码图片代码：
ValidateCode.ashx
<%@ WebHandler Language="C#" Class="ValidateCode" %> using System;
using System.Web;
using System.Drawing;
using System.Web.SessionState; public class ValidateCode : IHttpHandler, IRequiresSessionState
{
HttpContext context;
public void ProcessRequest (HttpContext context1) {
this.context = context1;
CreateCheckCodeImage(GenerateCheckCode());
} private string GenerateCheckCode()
{
int number;
char code;
string checkCode = String.Empty; System.Random random = new Random(); for (int i = ; i < ; i++)
{
number = random.Next(); if (number % == )
code = (char)('' + (char)(number % ));
else
code = (char)('' + (char)(number % ));
//code = (char)('A' + (char)(number % 26)); checkCode += code.ToString();
} //添加Session值
context.Session.Add("vCode", checkCode);
return checkCode;
} private void CreateCheckCodeImage(string checkCode)
{
if (checkCode == null || checkCode.Trim() == String.Empty)
return; System.Drawing.Bitmap image = new System.Drawing.Bitmap((int)Math.Ceiling((checkCode.Length * 12.5)), );
Graphics g = Graphics.FromImage(image); try
{
//生成随机生成器
Random random = new Random(); //清空图片背景色
g.Clear(Color.White); //画图片的背景噪音线
for (int i = ; i < ; i++)
{
int x1 = random.Next(image.Width);
int x2 = random.Next(image.Width);
int y1 = random.Next(image.Height);
int y2 = random.Next(image.Height); g.DrawLine(new Pen(Color.Silver), x1, y1, x2, y2);
} Font font = new System.Drawing.Font("Arial", , (System.Drawing.FontStyle.Bold | System.Drawing.FontStyle.Italic));
System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush(new Rectangle(, , image.Width, image.Height), Color.Blue, Color.DarkRed, 1.2f, true);
g.DrawString(checkCode, font, brush, , ); //画图片的前景噪音点
for (int i = ; i < ; i++)
{
int x = random.Next(image.Width);
int y = random.Next(image.Height); image.SetPixel(x, y, Color.FromArgb(random.Next()));
} //画图片的边框线
g.DrawRectangle(new Pen(Color.Silver), , , image.Width - , image.Height - ); System.IO.MemoryStream ms = new System.IO.MemoryStream();
image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);
context.Response.ClearContent();
context.Response.ContentType = "image/Gif";
context.Response.BinaryWrite(ms.ToArray());
}
finally
{
g.Dispose();
image.Dispose();
}
} public bool IsReusable {
get {
return false;
}
} }