asp.net随机验证码（使用ashx）
ValidateCode.ashx
<%@ WebHandler Language="C#" Class="ValidateCode" %> using System; using System.Data; using System.Web; using System.Collections; using System.Web.Services; using System.Web.Services.Protocols; using System.Drawing;
public class ValidateCode : IHttpHandler {
public void ProcessRequest(HttpContext context) { context.Response.Cache.SetCacheability(HttpCacheability.NoCache);//特别注意，如不加，单击验证图片＇看不清换一张＇，无效果． this.CreateCheckCodeImage(GenerateCheckCode(context),context); }
public bool IsReusable { get { return false; } } private string GenerateCheckCode(HttpContext context) { int number; char code; string checkCode = String.Empty;
System.Random random = new Random();
for (int i = 0; i < 6; i++) { number = random.Next();
if (number % 2 == 0) code = (char)(''0'' + (char)(number % 10)); else if (number % 3 == 0) code = (char)(''A'' + (char)(number % 26)); else code = (char)(''a'' + (char)(number % 26)); checkCode += code.ToString(); }
context.Response.Cookies.Add(new HttpCookie("CheckCode", checkCode));//也可以存到Seesion里． //context.Session["CheckCode"] = checkCode; return checkCode; }
private void CreateCheckCodeImage(string checkCode, HttpContext context) { if (checkCode == null || checkCode.Trim() == String.Empty) return;
System.Drawing.Bitmap image = new System.Drawing.Bitmap((int)Math.Ceiling((checkCode.Length * 12.5)), 22); Graphics g = Graphics.FromImage(image);
&nbs
p; try { //生成随机生成器 Random random = new Random();
//清空图片背景色 g.Clear(Color.White);
//画图片的背景噪音线 for (int i = 0; i < 25; 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); }
Font font = new System.Drawing.Font("Arial", 12, (System.Drawing.FontStyle.Bold | System.Drawing.FontStyle.Italic)); 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);
//画图片的前景噪音点 for (int i = 0; i < 100; i++) { int x = random.Next(image.Width); int y = random.Next(image.Height);
image.SetPixel(x, y, Color.FromArgb(random.Next())); }
//画图片的边框线 g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);
System.IO.MemoryStream ms = new System.IO.MemoryStream(); image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif); context.Response.ClearContent(); context.Response.ContentType = "image/Gif"; context.Response.BinaryWrite(ms.ToArray()); } finally &nbs
p; { g.Dispose(); image.Dispose(); }
} }
页面:
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="Default" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" > <head runat="server"> <title>登录界面</title> </head> <body> <form id="form1" runat="server"> <div> 用户名：<asp:TextBox ID="txt_user" runat="server"></asp:TextBox> <br /> 密 码：<asp:TextBox ID="txt_pwd" runat="server" TextMode="Password"></asp:TextBox><br /> 验证码： <asp:TextBox ID="txtCheckCode" runat="server"></asp:TextBox> <img src="ValidateCode.ashx" onclick="this.src=''ValidateCode.ashx''" title="看不清换一张" /> <asp:Label ID="lblMessage" runat="server"></asp:Label> <br /> <asp:Button ID="Button1" runat="server" OnClick="Button1_Click" Text="登录" /></div>
r /> </form> </body> </html>
后台代码:
using System; using System.Data; using System.Configuration; using System.Collections; using System.Web; using System.Web.Security; using System.Web.UI; using System.Web.UI.WebControls; using System.Web.UI.WebControls.WebParts; using System.Web.UI.HtmlControls;
public partial class Default : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) {
}
protected void Button1_Click(object sender, EventArgs e) { if (Request.Cookies["CheckCode"] == null) { lblMessage.Text = "您的浏览器设置已被禁用 Cookies，您必须设置浏览器允许使用 Cookies 选项后才能使用本系统。"; lblMessage.Visible = true; return; }
if (String.Compare(Request.Cookies["CheckCode"].Value, txtCheckCode.Text, true) != 0) { lblMessage.Text = "验证码错误，请输入正确的验证码。"; lblMessage.Visible = true; return; }
//在这执行下一步 //CheckCode是存到Session里的 //if (Session["CheckCode"] != null) //{ // if (String.Compare(Session["CheckCode"].ToString(), txtCheckCode.Text.Trim(), true) != 0) // { // lblMessage.Text = "验证码错误，请输入正确的验证码。"; // lblMessage.Visible = true; // return; // } // else // {//在这执行下一步 // } //} } }