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>
希望本文所述对大家asp.net程序设计有所帮助。
更多asp.net简单生成验证码的方法。