本文实例讲述了ASP.NET实现的生成验证码功能。分享给大家供大家参考，具体如下：
生成验证码原理：产生随机字符，并将字符生成为图片，同时储存到Session里去，然后验证用户输入的内容是否与Session中的验证码相符即可。
效果图：用户可以点击切换验证码信息。
一般处理程序：CheckCodeHandler.cs
<%@ WebHandler Language="C#" Class="CheckCodeHandler" %>
using System;
using System.Web;
using System.Text;
using System.Drawing;
using System.Web.SessionState;
public class CheckCodeHandler : IHttpHandler,IRequiresSessionState
{
//产生验证码的字符集
public string charcode = "2,3,4,5,6,8,9,A,B,C,D,E,F,G,H,J,K,M,N,P,R,S,U,W,X,Y,a,b,c,d,e,f,g,h,j,k,m,n,p,r,s,u,w,x,y";
public void ProcessRequest (HttpContext context) {
string validateCode = CreateRandomCode(4);
context.Session["ValidateCode"] = validateCode;//将验证码保存到session中
CreateCodeImage(validateCode, context);
}
public bool IsReusable {
get {
return false;
}
}
/// <summary>
/// 生成验证码
/// </summary>
/// <param name="n">验证码个数</param>
/// <returns>验证码字符串</returns>
public string CreateRandomCode(int n)
{
string[] CharArray = charcode.Split(',');//将字符串转换为字符数组
string randomCode = "";
int temp = -1;
Random rand = new Random();
for (int i = 0; i < n; i++)
{
if (temp != -1)
{
rand = new Random(i * temp * ((int)DateTime.Now.Ticks));
}
int t = rand.Next(CharArray.Length - 1);
if (temp != -1 && temp == t)
{
return CreateRandomCode(n);
}
temp = t;
randomCode += CharArray[t];
}
return randomCode;
}
public void CreateCodeImage(string checkCode, HttpContext context)
{
int iwidth = (int)(checkCode.Length * 13);
System.Drawing.Bitmap image = new System.Drawing.Bitmap(iwidth, 20);
Graphics g = Graphics.FromImage(image);
Font f = new System.Drawing.Font("Arial", 12, (System.Drawing.FontStyle.Italic | System.Drawing.FontStyle.Bold));
// 前景色
Brush b = new System.Drawing.SolidBrush(Color.Black);
// 背景色
g.Clear(Color.White);
// 填充文字
g.DrawString(checkCode, f, b, 0, 1);
// 随机线条
Pen linePen = new Pen(Color.Gray, 0);
Random rand = new Random();
for (int i = 0; i < 5; i++)
{
int x1 = rand.Next(image.Width);
int y1 = rand.Next(image.Height);
int x2 = rand.Next(image.Width);
int y2 = rand.Next(image.Height);
g.DrawLine(linePen, x1, y1, x2, y2);
}
// 随机点
for (int i = 0; i < 30; i++)
{
int x = rand.Next(image.Width);
int y = rand.Next(image.Height);
image.SetPixel(x, y, Color.Gray);
}
// 边框
g.DrawRectangle(new Pen(Color.Gray), 0, 0, image.Width - 1, image.Height - 1);
// 输出图片
System.IO.MemoryStream ms = new System.IO.MemoryStream();
image.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
context.Response.ClearContent();
context.Response.ContentType = "image/jpeg";
context.Response.BinaryWrite(ms.ToArray());
g.Dispose();
image.Dispose();
}
}
封装成类库：ValidateNumber.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Drawing;
using System.Web.UI;
using System.Drawing.Drawing2D;
using System.IO;
using System.Drawing.Imaging;
/// <summary>
///ValidateNumber 生成验证码
/// </summary>
public class ValidateNumber
{
//产生验证码的字符集 （易混淆的字符去掉）
private string charcode = "2,3,4,5,6,8,9,A,B,C,D,E,F,G,H,J,K,M,N,P,R,S,U,W,X,Y,a,b,c,d,e,f,g,h,j,k,m,n,p,r,s,u,w,x,y";
/// <summary>
/// 验证码的最大长度
/// </summary>
public int MaxLength
{
get { return 10; }
}
/// <summary>
/// 验证码的最小长度
/// </summary>
public int MinLength
{
get { return 1; }
}
/// <summary>
/// 生成验证码
/// </summary>
/// <param name="length">指定验证码的长度</param>
/// <returns></returns>
public string CreateValidateNumber(int length)
{
string[] CharArray = charcode.Split(',');//将字符串转换为字符数组
string randomCode = "";
int temp = -1;
Random rand = new Random();
for (int i = 0; i < length; i++)
{
if (temp != -1)
{
rand = new Random(i * temp * ((int)DateTime.Now.Ticks));
}
int t = rand.Next(CharArray.Length - 1);
if (temp != -1 && temp == t)
{
return CreateValidateNumber(length);
}
temp = t;
randomCode += CharArray[t];
}
return randomCode;
}
/// <summary>
/// 创建验证码的图片
/// </summary>
/// <param name="context">context对象</param>
/// <param name="validateNum">验证码</param>
public void CreateValidateGraphic(HttpContext context,string validateNum)
{
int iwidth = (int)(validateNum.Length * 14);
Bitmap image = new Bitmap(iwidth, 22);
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);
//画图片的干扰线
for (int i = 0; i < 25; 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 Font("Arial", 12, (FontStyle.Bold | FontStyle.Italic));
LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height),
Color.Blue, Color.DarkRed, 1.2f, true);
g.DrawString(validateNum, font, brush, 3, 2);
//画图片的前景干扰点
for (int i = 0; i < 100; 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), 0, 0, image.Width - 1, image.Height - 1);
//保存图片数据
MemoryStream stream = new MemoryStream();
image.Save(stream, ImageFormat.Jpeg);
//输出图片
context.Response.Clear();
context.Response.ContentType = "image/jpeg";
context.Response.BinaryWrite(stream.ToArray());
}
finally
{
g.Dispose();
image.Dispose();
}
}
/// <summary>
/// 得到验证码图片的长度
/// </summary>
/// <param name="validateNumLength">验证码的长度</param>
/// <returns></returns>
public static int GetImageWidth(int validateNumLength)
{
return (int)(validateNumLength * 14);
}
/// <summary>
/// 得到验证码图片的高度
/// </summary>
/// <returns></returns>
public static double GetImageHeight()
{
return 22;
}
}
附：完整实例代码点击此处本站下载。
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