一般驗證碼的生成方法都是相同的,主要的步驟都有兩步
第一步：隨機出一系統(tǒng)驗證碼的數(shù)字或字母，順便把隨機生成的數(shù)字或字母寫入Cookies 或者 Session。
第二步：用第一步隨機出來的數(shù)字或字母來合成圖片。
可以看出來驗證碼的復雜度主要是第二步來完成，你可以根據(jù)自己所要的復雜度來設(shè)定。
我們一起來看看：
第一步：隨機生成數(shù)字或字母的方法
/// <summary> /// 生成驗證碼的隨機數(shù) /// </summary> /// <returns>返回五位隨機數(shù)</returns> private string GenerateCheckCode() { int number; char code; string checkCode = String.Empty; Random random = new Random(); for (int i = 0; i < 5; i++)//可以任意設(shè)定生成驗證碼的位數(shù) { number = random.Next(); if (number % 2 == 0) code = (char)('0' + (char)(number % 10)); else code = (char)('A' + (char)(number % 26)); checkCode += code.ToString(); } Response.Cookies.Add(new HttpCookie("CheckCode", checkCode));//寫入COOKIS Session["CheckCode"] = checkCode; //寫入Session，可以任意選一下 return checkCode; } 第二步：生成圖片
/// <summary> /// 生成驗證碼圖片 /// </summary> /// <param name="checkCode"></param> private void CreateCheckCodeImage(string checkCode) { if (checkCode == null || checkCode.Trim() == String.Empty) return; Bitmap image = new Bitmap((int)Math.Ceiling((checkCode.Length * 12.5)), 22); Graphics g = Graphics.FromImage(image); try { //生成隨機生成器 Random random = new Random(); //清空圖片背景色 g.Clear(Color.White); //畫圖片的背景噪音線 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)); LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height), Color.Blue, Color.DarkRed, 1.2f, true); g.DrawString(checkCode, font, brush, 2, 2); //畫圖片的前景噪音點 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())); } //畫圖片的邊框線 g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1); MemoryStream ms = new MemoryStream(); image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif); Response.ClearContent(); Response.ContentType = "image/Gif"; Response.BinaryWrite(ms.ToArray()); } finally {//釋放對象資源 g.Dispose(); image.Dispose(); } *完整程序
先在VS2005里面的項目里面添加一個 checkCode.aspx 文件，在checkCode.aspx.cs 代碼文件中添加如下完整代碼
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;using System.IO;using System.Drawing.Drawing2D;public partial class checkCode : System.Web.UI.Page{ protected void Page_Load(object sender, EventArgs e) { CreateCheckCodeImage(GenerateCheckCode());//調(diào)用下面兩個方法; } /// <summary> /// 生成驗證碼的隨機數(shù) /// </summary> /// <returns>返回五位隨機數(shù)</returns> private string GenerateCheckCode() { int number; char code; string checkCode = String.Empty; Random random = new Random(); for (int i = 0; i < 5; i++)//可以任意設(shè)定生成驗證碼的位數(shù) { number = random.Next(); if (number % 2 == 0) code = (char)('0' + (char)(number % 10)); else code = (char)('A' + (char)(number % 26)); checkCode += code.ToString(); } Response.Cookies.Add(new HttpCookie("CheckCode", checkCode));//寫入COOKIS Session["CheckCode"] = checkCode; //寫入Session，可以任意選一下 return checkCode; } /// <summary> /// 生成驗證碼圖片 /// </summary> /// <param name="checkCode"></param> private void CreateCheckCodeImage(string checkCode) { if (checkCode == null || checkCode.Trim() == String.Empty) return; Bitmap image = new Bitmap((int)Math.Ceiling((checkCode.Length * 12.5)), 22); Graphics g = Graphics.FromImage(image); try { //生成隨機生成器 Random random = new Random(); //清空圖片背景色 g.Clear(Color.White); //畫圖片的背景噪音線 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)); LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height), Color.Blue, Color.DarkRed, 1.2f, true); g.DrawString(checkCode, font, brush, 2, 2); //畫圖片的前景噪音點 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())); } //畫圖片的邊框線 g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1); MemoryStream ms = new MemoryStream(); image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif); Response.ClearContent(); Response.ContentType = "image/Gif"; Response.BinaryWrite(ms.ToArray()); } finally {//釋放對象資源 g.Dispose(); image.Dispose(); } }} 上面生成驗證碼的頁面都做好了，我們來調(diào)用看看：
在你需要用到驗證碼的地方加了Image控件
<asp:Image ID="Image1" runat="server" ImageUrl="~/checkCode.aspx" />
這樣驗證碼就會顯示到Image控件上面了！
顯示弄好了，當然我們要判斷一下用戶的輸入是否正確！
只要我們?nèi)〉糜脩糨斎氲闹蹈鶦ookis或者Session對比就OK了
取Cookies的值 Request.Cookies["CheckCode"].Value
取Session的值 Session["CheckCode"].ToString() （最好先判斷Session是否空）
如果不要區(qū)分大小寫的話，就把用戶輸入的值和Cookies或Session的值都轉(zhuǎn)成大寫或都小寫
附用法
protected void Button1_Click(object sender, EventArgs e) { if (Request.Cookies["CheckCode"].Value == TextBox1.Text.Trim().ToString()) { Response.Write("Cookies is right"); } else { Response.Write("Cookies is wrong"); } if (Session["CheckCode"] != null) { if (Session["CheckCode"].ToString().ToUpper() == TextBox1.Text.Trim().ToString().ToUpper()) //這樣寫可以不能區(qū)分大小寫 { Response.Write("Session is right"); } else { Response.Write("Session is wrong"); } } } 以上就是本文的全部內(nèi)容，教大家如何制作ASP.NET驗證碼，希望大家喜歡。
