北京北大青鳥校區(qū)學術老師指導：ASP.NET驗證碼

此技術文章由北京北大青鳥校區(qū)學術部丁老師提供：
1.創(chuàng)建“一般處理程序”（北京北大青鳥校區(qū)）
using System;
using System.IO;
using System.Drawing;
using System.Drawing.Imaging;
using System.Text;
using System.Collections;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
namespace WebApplication1
{
///
/// ChkCode 的摘要說明
///
public class ChkCode : IHttpHandler
{
//驗證碼的字符集
private readonly char[] character = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ".ToCharArray();
public void ProcessRequest(HttpContext context)
{
string chkCode = string.Empty;
//顏色列表，用于驗證碼、噪線、噪點
Color[] color = { Color.Black, Color.Red, Color.Blue, Color.Green, Color.Orange, Color.Brown, Color.Brown, Color.DarkBlue };
//字體列表，用于驗證碼
string[] font = { "Times New Roman", "MS Mincho", "Book Antiqua", "Gungsuh", "PMingLiU", "Impact" };
Random rnd = new Random();
//生成驗證碼字符串
for (int i = 0; i < 4; i++)
{
chkCode += character[rnd.Next(character.Length)];
}
//將驗證碼寫入Session
context.Session["ChkCode"] = chkCode;
Bitmap bmp = new Bitmap(100, 40);
Graphics g = Graphics.FromImage(bmp);
g.Clear(Color.White);
//畫噪線
for (int i = 0; i < 10; i++)
{
int x1 = rnd.Next(100);
int y1 = rnd.Next(40);
int x2 = rnd.Next(100);
int y2 = rnd.Next(40);
Color clr = color[rnd.Next(color.Length)];
g.DrawLine(new Pen(clr), x1, y1, x2, y2);
}
//畫驗證碼字符串 （北京北大青鳥校區(qū)）
for (int i = 0; i < chkCode.Length; i++)
{
string fnt = font[rnd.Next(font.Length)];
Font ft = new Font(fnt, 18);
Color clr = color[rnd.Next(color.Length)];
g.DrawString(chkCode[i].ToString(), ft, new SolidBrush(clr), (float)i * 20 + 8, (float)8);
}
//畫噪點
for (int i = 0; i < 100; i++)
{
int x = rnd.Next(bmp.Width);
int y = rnd.Next(bmp.Height);
Color clr = color[rnd.Next(color.Length)];
bmp.SetPixel(x, y, clr);
}
//清除該頁輸出緩存，設置該頁無緩存
context.Response.Buffer = true;
context.Response.ExpiresAbsolute = System.DateTime.Now.AddMilliseconds(0);
context.Response.Expires = 0;
context.Response.CacheControl = "no-cache";
context.Response.AppendHeader("Pragma", "No-Cache");
//將驗證碼圖片寫入內存流，并將其以 "image/Png" 格式輸出
MemoryStream ms = new MemoryStream();
try
{
bmp.Save(ms, ImageFormat.Png);
context.Response.ClearContent();
context.Response.ContentType = "image/Png";
context.Response.BinaryWrite(ms.ToArray());
}
finally
{
//顯式釋放資源
bmp.Dispose();
g.Dispose();
}
}
public bool IsReusable
{
get
{
return false;
}
}
}
}（北京北大青鳥校區(qū)）

2.創(chuàng)建測試頁


（北京北大青鳥校區(qū)）