[研究]ASP.NET WebForm CAPTCHA圖形驗證碼
2021-11-19
Visual Studio 2022 + C# + ASP.NET + WebForm
參考
https://dotblogs.com.tw/shadow/2011/10/05/38823
Default.aspx
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="CAPTCHATest.Default" %>
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title></title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
<img src="ValidateNumber.ashx" alt="驗證碼" name="imgCode" />
<input type="button" onclick="form1.imgCode.src='ValidateNumber.ashx?' + Math.random();" value="重新整理" />
<br />
<asp:Button Text="送出" ID="Button1" runat="server" OnClick="btn_submit_Click" /><br />
<asp:Label ID="Label1" name="Label1" runat="server"></asp:Label>
</div>
</form>
</body>
</html>
|
Default.aspx.cs
using System;
namespace CAPTCHATest
{
public partial class Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
Label1.Text = "";
}
protected void btn_submit_Click(object sender, EventArgs e)
{
string captcheValidateNumber = Session["ValidateNumber"].ToString();
if (TextBox1.Text.Trim() == captcheValidateNumber)
{
Label1.ForeColor = System.Drawing.Color.Red;
Label1.Text = "OK";
}
else
{
Label1.ForeColor = System.Drawing.Color.Green;
Label1.Text = "Fail";
}
}
}
} |
ValidateNumber.ashx
using System;
using System.Drawing;
using System.Web;
using System.Web.SessionState;
namespace CAPTCHATest
{
/// <summary>
/// ValidateNumber 的摘要描述
/// </summary>
public class ValidateNumber : IHttpHandler, IRequiresSessionState
{
public void ProcessRequest(HttpContext context)
{
int NumCount = 5;//預設產生5位亂數
if (!string.IsNullOrEmpty(context.Request.QueryString["NumCount"]))
{//有指定產生幾位數
//字串轉數字，轉型成功的話儲存到 NumCount，不成功的話，NumCount會是0
Int32.TryParse(context.Request.QueryString["NumCount"].Replace("'", "''"), out NumCount);
}
if (NumCount == 0) NumCount = 5;
//取得亂數
var rand = new Random();
// 產生4位數字，1000~9999
string str_ValidateCode = rand.Next(1000, 9999).ToString();
/*用於驗證的Session*/
context.Session["ValidateNumber"] = str_ValidateCode;
//取得圖片物件
System.Drawing.Image image = this.CreateCheckCodeImage(context, str_ValidateCode);
System.IO.MemoryStream ms = new System.IO.MemoryStream();
image.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
/*輸出圖片*/
context.Response.Clear();
context.Response.ContentType = "image/jpeg";
context.Response.BinaryWrite(ms.ToArray());
ms.Close();
}
#region 產生圖片
private System.Drawing.Image CreateCheckCodeImage(HttpContext context, string checkCode)
{
System.Drawing.Bitmap image = new System.Drawing.Bitmap((checkCode.Length * 20), 30);//產生圖片，寬20*位數，高30像素
System.Drawing.Graphics g = Graphics.FromImage(image);
//生成隨機生成器
Random random = new Random(Guid.NewGuid().GetHashCode());
int int_Red = 0;
int int_Green = 0;
int int_Blue = 0;
int_Red = random.Next(256);//產生0~255
int_Green = random.Next(256);//產生0~255
int_Blue = (int_Red + int_Green > 400 ? 0 : 400 - int_Red - int_Green);
int_Blue = (int_Blue > 255 ? 255 : int_Blue);
//清空圖片背景色
g.Clear(Color.FromArgb(int_Red, int_Green, int_Blue));
//畫圖片的背景噪音線
for (int i = 0; i <= 24; 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);
g.DrawEllipse(new Pen(Color.DarkViolet), new System.Drawing.Rectangle(x1, y1, x2, y2));
}
Font font = new System.Drawing.Font("Arial", 20, (System.Drawing.FontStyle.Bold));
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);
for (int i = 0; i <= 99; i++)
{
//畫圖片的前景噪音點
int x = random.Next(image.Width);
int y = random.Next(image.Height);
image.SetPixel(x, y, Color.FromArgb(random.Next()));
}
//畫圖片的邊框線
g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);
return image;
}
#endregion
/*實作 IHttpHandler介面的方法，不可刪除*/
public bool IsReusable
{
get
{
return false;
}
}
}
} |
(完)
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