ASP.NET随机码生成示例

最新推荐文章于 2025-08-20 15:51:36 发布

mndn_nana

最新推荐文章于 2025-08-20 15:51:36 发布

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文章标签： asp.net random session image string object

本文介绍了一个使用C#生成随机验证码图片的方法。通过创建位图、绘制干扰线和点，以及生成随机字符串，最终将验证码图片输出给客户端。文章详细展示了如何设置验证码并将其存储在Session中。

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using System.Drawing;
  using System.Drawing.Imaging;
  using System.Drawing.Drawing2D;
  生成页代码

  using System;
  using System.Data;
  using System.Configuration;
  using System.Collections;
  using System.Web;
  using System.Web.Security;
  using System.Web.UI;
  using System.Web.UI.WebControls;
  using System.Web.UI.WebControls.WebParts;
  using System.Web.UI.HtmlControls;
  using System.Drawing;
  using System.Drawing.Imaging;
  using System.Drawing.Drawing2D;

  public partial class getRandImg : System.Web.UI.Page
  ...{
   protected void Page_Load(object sender, EventArgs e)
   ...{
   //生成随机码图片
   SetValidateCode();
   //生成页面不保存到cache
   Response.Cache.SetNoStore();
   }

   //设置验证码
   private void SetValidateCode()
   ...{
   //新建位图
   Bitmap newBitmap = new Bitmap(
   71,
   23,
   PixelFormat.Format32bppArgb
   );
   //从位图获得绘图画面
   Graphics g = Graphics.FromImage(newBitmap);
   //随机数生成器
   Random r = new Random();
   //绘图画面清空
   g.Clear(Color.White);
   //绘图画面划线干扰
   for (int i = 0; i < 50; i++)
   ...{
   int x1 = r.Next(newBitmap.Width);
   int x2 = r.Next(newBitmap.Width);
   int y1 = r.Next(newBitmap.Height);
   int y2 = r.Next(newBitmap.Height);
   g.DrawLine(new Pen(
   Color.FromArgb(r.Next())),
   x1,
   y1,
   x2,
   y2
   );
   }
   //绘图画面点数干扰
   for (int i = 0; i < 100; i++)
   ...{
   int x = r.Next(newBitmap.Width);
   int y = r.Next(newBitmap.Height);
   newBitmap.SetPixel(
   x,
   y,
   Color.FromArgb(r.Next())
   );
   }
   //获得随机字符串（5位长度）
   string value = GenerateRandom(5);
   //随机字符串赋值给Session
   Session["RandCode"] = value;
   //定义图片显示字体样式
   Font font = new Font(
   "Arial",
   14,
   FontStyle.Bold
   );
   Random rr = new Random();
   int yy = rr.Next(1, 4);
   //定义随机字符串显示图片刷子
   LinearGradientBrush brush = new LinearGradientBrush(
   new Rectangle(0, 0, 71, 23),
   Color.Red,
   Color.Blue,
   1.2f,
   true
   );
   g.DrawString(value, font, brush, 2, yy);
   g.DrawRectangle(new Pen(
   Color.Silver),
   0,
   0,
   70,
   22
   );
   System.IO.MemoryStream ms = new System.IO.MemoryStream();
   newBitmap.Save(ms, ImageFormat.Gif);
   //输出图片
   Response.ClearContent();
   Response.ContentType = "image/gif";
   Response.BinaryWrite(ms.ToArray());
   }

   //常量集
   private static char[] constant =...{
   '0','1','2','3','4','5','6','7','8','9',
   'a','b','c','d','e','f','g','h','i','j',
   'k','l','m','n','o','p','q','r','s','t',
   'u','v','w','x','y','z'
   };


   //生成随机字符串
   public static string GenerateRandom(int Length)
   ...{
   System.Text.StringBuilder newRandom = new System.Text.StringBuilder(36);
   Random rd = new Random();
   for (int i = 0; i < Length; i++)
   ...{
   newRandom.Append(constant[rd.Next(36)]);
   }
   return newRandom.ToString();
   }
  }
// 使用随机图片的页面，IMAGE控件的写法如下：

  <asp:Image ID="Image1" ImageUrl="~/getRandImg.aspx" runat="server" />