首先看下效果實現（由於gif螢幕錄製軟體是即時找的，有些失禎）
代碼主要就是繪製驗證碼類的實現
using System;using System.Collections.Generic;using System.Linq;using System.Web;using System.Drawing;using System.IO;namespace SecurityCodePic{ public class DrawingSecurityCode { /// <summary> /// 產生驗證碼，並返回 /// </summary> /// <returns></returns> public string GetSecurityCode(int n) { string code = GenerateCheckCode(n); CreateCheckCodeImage(code); return code; } /// <summary> /// 動態產生指定數目的隨機數或字母 /// </summary> /// <param name="num">整數</param> /// <returns>返回驗證碼字串</returns> private string GenerateCheckCode(int num) { int number;//定義變數 char code; string checkCode = String.Empty; //Null 字元串，唯讀 Random random = new Random(); //定義隨機變數執行個體 for (int i=0; i < num;i++ ) { //利用for迴圈產生指定數目的隨機數或字母 number = random.Next(); //返回一個小於指定的最大值的非負的隨機數 next有三個建構函式 if (number % 2 == 0) {//產生一個一位元 code = (char)('0' + (char)(number % 10)); } else { //產生一個大寫字母 code = (char)('A'+(char)(number % 26)); } checkCode += code.ToString(); } return checkCode; } /// <summary> /// 根據驗證碼字串產生驗證碼圖片 /// </summary> /// <param name="checkCode">驗證碼字串</param> private void CreateCheckCodeImage(string checkCode) { if (checkCode == null || checkCode.Trim() == String.Empty) return; // 引用System.Drawing類庫 Bitmap myImage = new Bitmap(80, 30);//產生一個指定大小的位元影像 Graphics graphics = Graphics.FromImage(myImage); //從一個位元影像產生一個畫布 try { graphics.Clear(Color.White); //清除整個繪畫面並以指定的背景色填充,這裡是把背景色設為白色 Random random = new Random(); //執行個體化一個偽隨機數產生器 //畫圖片的前景噪音點,這裡有100個 for (int i = 0; i < 100; i++) { int x = random.Next(myImage.Width); int y = random.Next(myImage.Height); myImage.SetPixel(x, y, Color.FromArgb(random.Next()));//指定座標為x,y處的像素的顏色 } //畫圖片的背景雜音線,這裡為2條 for (int i = 0; i < 2; i++) { int x1 = random.Next(myImage.Width); int x2 = random.Next(myImage.Width); int y1 = random.Next(myImage.Height); int y2 = random.Next(myImage.Height); graphics.DrawLine(new Pen(Color.Black), x1, y1, x2, y2); //繪製一條座標x1,y1到座標x2,y2的指定顏色的線條，這裡的線條為黑色 } Font font = new Font("Arial", 15, FontStyle.Bold); //定義特定的文字格式設定,這裡的字型為Arial，大小為15,字型加粗 //根據矩形、起始顏色和結束顏色以及方向角度產生一個LinearGradientBrush執行個體---線性漸層 System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush( new Rectangle(0, 0, myImage.Width, myImage.Height),//在座標0,0處執行個體化一個和myImage同樣大小的矩形 Color.Blue, Color.Red, 1.2f, true); //繪製文本字串 graphics.DrawString(checkCode, font, brush, 2, 2); //繪製有座標組、寬度和高度指定的矩形---畫圖片的邊框線 graphics.DrawRectangle(new Pen(Color.Silver), 0, 0, myImage.Width - 1, myImage.Height - 1); //建立其支援儲存空間為記憶體的流 MemoryStream ms = new MemoryStream(); //將此映像以指定格式儲存到指定的流中 myImage.Save(ms, System.Drawing.Imaging.ImageFormat.Gif); //這裡是以gif的格式儲存到記憶體中 HttpContext.Current.Response.ClearContent(); //清除緩衝區流中的所有內容輸出 HttpContext.Current.Response.ContentType = "image/Gif"; //擷取或設定輸出資料流的HTTP MIME類型 HttpContext.Current.Response.BinaryWrite(ms.ToArray()); //將一個二進位字串寫入HTTP輸出資料流 } finally { //釋放佔用資源 graphics.Dispose(); myImage.Dispose(); } } }}
然後使用SecurityCode.ashx檔案調用上面類的方法實現
using System;using System.Collections.Generic;using System.Linq;using System.Web;namespace SecurityCodePic{ /// <summary> /// SecurityCode1 的摘要說明 /// </summary> public class SecurityCode1 : IHttpHandler { public void ProcessRequest(HttpContext context) { DrawingSecurityCode sc = new DrawingSecurityCode(); string SecurityCode = sc.GetSecurityCode(6); } public bool IsReusable { get { return false; } } }}
最後就是ASP.NET頁面圖片路徑的引用了
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="SecurityCode_Test.aspx.cs" Inherits="SecurityCodePic.SecurityCode_Test" %><!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>驗證碼的實現</title> <style type="text/css"> #VCodeImg { cursor: pointer;} </style></head><body> <form id="form1" runat="server"> <div> <img id="VCodeImg" src="SecurityCode.ashx" alt="驗證碼" onclick="javascript:RefreshCode();" /> </div> </form> <script type="text/javascript"> function RefreshCode() { var random = Math.random(); var img = document.getElementById("VCodeImg"); img.src = "SecurityCode.ashx?" + random; //加上無意義的隨機參數，瀏覽器才會認為是新地址，就會重新讀取資料 } </script></body></html>
以上就是本文的全部，對了，還有源碼下載分享給大家，歡迎大家下載。
源碼分享：ASP.NET驗證碼實現
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