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ASP.NET图片验证码学习!

1. 新建一个Validate.aspx,然后在Validate.aspx.cs编写代码:

using System;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Web;
using System.Drawing;
using System.Web.SessionState;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;
using System.Drawing.Imaging;
using System.IO;

 

public partial class Validate : System.Web.UI.Page
{
  protected void Page_Load(object sender, EventArgs e)
  {
      this.CreateCheckCodeImage(RndNum());

  }
  private string RndNum()
  {
      int number;
      char code;
      string checkCode = String.Empty;

      System.Random random = new Random();

      for (int i = 0; i < 4; i++)
      {
         number = random.Next();
         if (number % 2 == 0)
            code = (char)(‘0‘ + (char)(number % 10));
         else
            code = (char)(‘A‘ + (char)(number % 26));
         checkCode += code.ToString();
      }

      Session["CheckCode"] = checkCode;
      return checkCode;
  }
  private void CreateCheckCodeImage(string checkCode)
  {
      if (checkCode == null || checkCode.Trim() == String.Empty)
         return;
      System.Drawing.Bitmap image = new System.Drawing.Bitmap((int)Math.Ceiling((checkCode.Length * 12.5)), 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);
         // 画图片的背景噪音线
         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 System.Drawing.Font("Arial", 12, (System.Drawing.FontStyle.Bold | System.Drawing.FontStyle.Italic));
      System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush(new Rectangle(0, 0, image.Width, image           .Height), Color.Blue, Color.DarkRed, 1.2f, true);
      g.DrawString(checkCode, font, brush, 2, 2);
         // 画图片的前景噪音点
         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);
      System.IO.MemoryStream ms = new System.IO.MemoryStream();
      image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);
      Response.ClearContent();
      Response.ContentType = "image/Gif";
      Response.BinaryWrite(ms.ToArray());
    }
    finally
    {
      g.Dispose();
      image.Dispose();
    }
  }

}

 

2. 在前台你想添加的页面添加这段代码:(我这里假设是在登录页面Login.aspx中添加图片验证码)

<img id="ImageCode" src="http://www.mamicode.com/Validate.aspx" style="cursor:pointer" onm ouseup="RefreshImage()" alt="点击重刷新"/>

 还需要在<head>...</head>之间添加这段代码:

<script language ="javascript" type="text/javascript" >
  function RefreshImage()

   {
    var img = document.getElementById("ImageCode"); // 这里的ImageCode就是上面你取图片的Id名字,这里要一致!
    img.src = http://www.mamicode.com/img.src + ‘?‘;
  }
</script>

 

3. 在后台Login.aspx.cs中添加实现代码:

引用......

public partial class Login : System.Web.UI.Page
{
  protected void Page_Load(object sender, EventArgs e)
  {

  }

  // 登录按钮点击事件处理
  protected void btnLogin_Click(object sender, ImageClickEventArgs e)
  {
    User user = new User();
    user.LoginId = this.txt_LoginId.Text.Trim();
    user.LoginPwd = this.txt_LoginPwd.Text.Trim();
    if (this.txtCode.Text.ToLower() == Session["CheckCode"].ToString().ToLower())
    {
      Response.Redirect("Index.aspx");

      else
      {
        Session["user"] = null;
        this.Page.ClientScript.RegisterStartupScript(this.GetType(), "str", "<script>alert(\"登录失败!!\")</script>");
      }
    }
    else
    {
      this.Page.ClientScript.RegisterStartupScript(this.GetType(), "str", "<script>alert(\"验证码错误!!\")</script>");
    }

  }

  // 新用户注册按钮点击事件处理
  protected void btn_Register_Click(object sender, ImageClickEventArgs e)
  {
    Response.Redirect("Register.aspx");
  }
}

 

最后运行出来的验证码就是这个样子的~~