ASP.NET实现的生成验证码功能示例【附demo源码】


            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;

  }

}







附：完整实例代码点击此处本站下载。

更多关于asp.net相关内容感兴趣的读者可查看本站专题：《asp.net操作json技巧总结》、《asp.net字符串操作技巧汇总》、《asp.net操作XML技巧总结》、《asp.net文件操作技巧汇总》、《asp.net ajax技巧总结专题》及《asp.net缓存操作技巧总结》。

希望本文所述对大家asp.net程序设计有所帮助。