2024年11月28日22:13:46 改
watermark.ashx代码:
<%@ WebHandler Language="C#" Class="WaterMark" %> using System; using System.Web; using System.Drawing; using System.Web.SessionState; public class WaterMark : IHttpHandler, IRequiresSessionState // 要使用session必须实现该接口,记得要导入System.Web.SessionState命名空间 { public void ProcessRequest(HttpContext context) { string checkCode = GenCode(4); // 产生4位随机字符 context.Session["Code"] = checkCode; //将字符串保存到Session中,以便需要时进行验证 System.Drawing.Bitmap image = new System.Drawing.Bitmap(70, 22); Graphics g = Graphics.FromImage(image); 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 int i; for (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.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 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 { g.Dispose(); image.Dispose(); } } public bool IsReusable { get { return false; } } private string GenCode(int num) { string[] source = { "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z", "#", "$", "%", "&", "@" }; string code = ""; Random rd = new Random(); int i; for (i = 0; i < num; i++) { code += source[rd.Next(0, source.Length)]; } return code; } }前端测试代码:
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Login.aspx.cs" Inherits="Login" %> <!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head runat="server"> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title></title> <script type="text/javascript"> function change() { var imgNode = document.getElementById("vimg"); imgNode.src = "watermark.ashx?t=" + (new Date()).valueOf(); // 这里加个时间的参数是为了防止浏览器缓存的问题 } </script> </head> <body> <form id="form1" runat="server"> <div> <asp:TextBox ID="txtCaptcha" runat="server" Width="119px" MaxLength="6" TextMode="SingleLine" Placeholder="请输入验证码"></asp:TextBox> <img src="watermark.ashx" id="vimg" alt="" /><input type="button" value="换一张图片" onclick="change()" /> <asp:Button ID="Button1" runat="server" Text="登录" OnClick="Button1_Click" /> </div> </form> </body> </html>
测试代码后端:
using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.UI; using System.Web.UI.WebControls; public partial class Login : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { } protected void Button1_Click(object sender, EventArgs e) { string code = txtCaptcha.Text.Trim(); string right_code = Session["Code"].ToString(); if (code.ToLower() == right_code.ToLower()) { Response.Write("验证码输入成功。"); } else { Response.Write("验证码错误。"); } } }