【C#工具类】C#生成加减法验证码
来源:互联网 发布:java 调用构造方法 编辑:程序博客网 时间:2024/06/05 10:45
开发出去的页面经常被别人以抓取的方式访问,造成服务器压力过大,IIS崩溃。这时候可以在经常被抓取的连接上添加验证码认证,可以有效的减轻服务器压力。
1.验证码输入页面
js:
function ValidateInput() { var Num = document.getElementById("txtNum").value; if (Num == "" || Num == str) { alert("请输入验证码!"); return false; } return true; }
页面:
<img src="ValidCode.aspx" alt="验证码"/> <asp:TextBox ID="txtNum" runat="server" Width="40px"></asp:TextBox> <asp:Button ID="btnContinue" runat="server" Text="查询" ToolTip="查询信息" OnClick="btnContinue_Click" OnClientClick="return ValidateInput();" />
这里IMG是一个页面生成的,这个页面也是重点。最后说,现在看验证。
2.后台验证
protected void btnContinue_Click(object sender, EventArgs e) { try { if (txtNum.Text == Session["ValidCode"].ToString()) { //.....Other Operation } else { RaiseAlert("验证码错误!"); } txtNum.Text = ""; } catch (Exception ex) { lblMsg.Text = ex.Message; }
3.验证码生成:
1).页面:(就是一个正常的页面。)
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="ValidCode.aspx.cs" Inherits="Admin_ValidCode" %><!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>无标题页</title></head><body> <form id="form1" runat="server"> <div> </div> </form></body></html>
2)后台生成:
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;using System.Drawing;//from http://i.aspx1.compublic partial class Admin_ValidCode : System.Web.UI.Page{ protected void Page_Load(object sender, EventArgs e) { this.CreateCheckCodeImage(GenerateCheckCode()); } private string GenerateCheckCode() { int intFirst, intSec, intTemp; string checkCode = String.Empty; System.Random random = new Random(); intFirst = random.Next(1, 10); intSec = random.Next(1, 10); switch (random.Next(1, 3).ToString()) { case "2": if (intFirst < intSec) { intTemp = intFirst; intFirst = intSec; intSec = intTemp; } checkCode = intFirst + "-" + intSec + "="; Session["ValidCode"] = intFirst - intSec; break; default: checkCode = intFirst + "+" + intSec + "="; Session["ValidCode"] = intFirst + intSec; break; } //Response.Cookies.Add(new HttpCookie("ValidCode",Movie.Common.AES.EncryptAes(checkCode))); return checkCode; } #region 产生波形滤镜效果 private const double PI = 3.1415926535897932384626433832795; private const double PI2 = 6.283185307179586476925286766559; private System.Drawing.Bitmap TwistImage(Bitmap srcBmp, bool bXDir, double dMultValue, double dPhase) { System.Drawing.Bitmap destBmp = new Bitmap(srcBmp.Width, srcBmp.Height); // 将位图背景填充为白色 System.Drawing.Graphics graph = System.Drawing.Graphics.FromImage(destBmp); graph.FillRectangle(new SolidBrush(System.Drawing.Color.White), 0, 0, destBmp.Width, destBmp.Height); graph.Dispose(); double dBaseAxisLen = bXDir ? (double)destBmp.Height : (double)destBmp.Width; for (int i = 0; i < destBmp.Width; i++) { for (int j = 0; j < destBmp.Height; j++) { double dx = 0; dx = bXDir ? (PI2 * (double)j) / dBaseAxisLen : (PI2 * (double)i) / dBaseAxisLen; dx += dPhase; double dy = Math.Sin(dx); // 取得当前点的颜色 int nOldX = 0, nOldY = 0; nOldX = bXDir ? i + (int)(dy * dMultValue) : i; nOldY = bXDir ? j : j + (int)(dy * dMultValue); System.Drawing.Color color = srcBmp.GetPixel(i, j); if (nOldX >= 0 && nOldX < destBmp.Width && nOldY >= 0 && nOldY < destBmp.Height) { destBmp.SetPixel(nOldX, nOldY, color); } } } return destBmp; } #endregion private void CreateCheckCodeImage(string checkCode) { if (checkCode == null || checkCode.Trim() == String.Empty) return; System.Drawing.Bitmap image = new System.Drawing.Bitmap((int)Math.Ceiling((checkCode.Length * 15.0)), 25); 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 for (int i = 0; i < 12; 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", 16, (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, 1, 1); //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())); //} //image = TwistImage(image, true, 3, 1);//画图片的波形滤镜效果 //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); Response.ClearContent(); Response.ContentType = "image/Gif"; Response.BinaryWrite(ms.ToArray()); } finally { g.Dispose(); image.Dispose(); } }}
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