如何使用ASP.NET实现生成验证码功能的实例代码

这篇文章主要介绍了ASP.NET实现的生成验证码功能,结合实例形式较为详细的分析了asp.net生成验证码的原理、步骤与相关实现技巧,并附带demo源码供读者下载参考,需要的朋友可以参考下

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;  }}

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