如何使用ASP.NET实现生成验证码功能的实例代码

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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