本文實例講述了asp.net簡單生成驗證碼的方法。分享給大家供大家參考，具體如下：
1.新建一個一般處理程序
namespace WebApplication1
{
/// <summary>
/// $codebehindclassname$ 的摘要說明
/// </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對象，繪圖
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();
//添加隨機的五個字母
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)));
//將圖片保存到輸出流中
basemap.Save(context.Response.OutputStream, ImageFormat.Gif);
context.Session["CheckCode"] = s.ToString(); //如果沒有實現IRequiresSessionState，則這裡會出錯，也無法生成圖片
context.Response.End();
}
public bool IsReusable
{
get
{
return false;
}
}
}
}
2.前台代碼
<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？點擊換一張" 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>
希望本文所述對大家asp.net程序設計有所幫助。
