asp.net简单生成验证码的方法

2024-07-10 13:29:42

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这篇文章主要介绍了asp.net简单生成验证码的方法,涉及asp.net生成随机数与绘制图片的相关技巧,具有一定参考借鉴价值,需要的朋友可以参考下

本文实例讲述了asp.net简单生成验证码的方法。分享给大家供大家参考，具体如下：

1.新建一个一般处理程序

namespace WebApplication1

{

/// <summary>

/// $codebehindclassname$ 的摘要说明

/// </summary>

[WebService(Namespace = "http://tempuri.org/")]

[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]

public class Handler1 : IHttpHandler, IRequiresSessionState

{

public void ProcessRequest(HttpContext context)

{

context.Response.ContentType = "image/gif";

//建立Bitmap对象，绘图

Bitmap basemap = new Bitmap(100, 30);

Graphics graph = Graphics.FromImage(basemap);

graph.FillRectangle(new SolidBrush(Color.White), 0, 0, 100, 30);

Font font = new Font(FontFamily.GenericSerif, 24, FontStyle.Bold, GraphicsUnit.Pixel);

Random r = new Random();

string letters = "ABCDEFGHIJKLMNPQRSTUVWXYZ";

string letter;

StringBuilder s = new StringBuilder();

//添加随机的五个字母

for (int x = 0; x < 5; x++)

{

letter = letters.Substring(r.Next(0, letters.Length - 1), 1);

s.Append(letter);

graph.DrawString(letter, font, new SolidBrush(Color.Black), x * 19, r.Next(0, 8));

}

//混淆背景

Pen linePen = new Pen(new SolidBrush(Color.Black), 2);

for (int x = 0; x < 6; x++)

graph.DrawLine(linePen, new Point(r.Next(0, 99), r.Next(0, 29)), new Point(r.Next(0, 99), r.Next(0, 29)));

//将图片保存到输出流中

basemap.Save(context.Response.OutputStream, ImageFormat.Gif);

context.Session["CheckCode"] = s.ToString(); //如果没有实现IRequiresSessionState，则这里会出错，也无法生成图片

context.Response.End();

}

public bool IsReusable

{

get

{

return false;

}

}

}

}

2.前台代码

<html xmlns="http://www.w3.org/1999/xhtml" >

<head runat="server">

<title></title>

</head>

<body>

<form id="form1" runat="server">

<div>

<asp:TextBox ID="txtCode" runat="server"></asp:TextBox>

<img id="imgCode" alt="看不清？点击换一张" src="Handler1.ashx" style="cursor:pointer" onclick="this.src=this.src+'?'" /><br />

<asp:Button ID="Button1" runat="server" onclick="Button1_Click" Text="Button" />

</div>

</form>

</body>

</html>