这篇文章主要介绍了asp.net实现的生成验证码功能,结合实例形式较为详细的分析了asp.net生成验证码的原理、步骤与相关实现技巧,并附带demo源码供读者下载参考,需要的朋友可以参考下
本文实例讲述了ASP.NET实现的生成验证码功能。分享给大家供大家参考，具体如下：
生成验证码原理：产生随机字符，并将字符生成为图片，同时储存到Session里去，然后验证用户输入的内容是否与Session中的验证码相符即可。
效果图：用户可以点击切换验证码信息。
一般处理程序：CheckCodeHandler.cs
<%@ WebHandler Language="C#" Class="CheckCodeHandler" %>
using System;
using System.Web;
using System.Text;
using System.Drawing;
using System.Web.SessionState;
public class CheckCodeHandler : IHttpHandler,IRequiresSessionState
{
//产生验证码的字符集
public string charcode = "2,3,4,5,6,8,9,A,B,C,D,E,F,G,H,J,K,M,N,P,R,S,U,W,X,Y,a,b,c,d,e,f,g,h,j,k,m,n,p,r,s,u,w,x,y";
public void ProcessRequest (HttpContext context) {
string validateCode = CreateRandomCode(4);
context.Session["ValidateCode"] = validateCode;//将验证码保存到session中
CreateCodeImage(validateCode, context);
}
public bool IsReusable {
get {
return false;
}
}
///
/// 生成验证码
///
/// 验证码个数
/// 验证码字符串
public string CreateRandomCode(int n)
{
string[] CharArray = charcode.Split(',');//将字符串转换为字符数组
string randomCode = "";
int temp = -1;
Random rand = new Random();
for (int i = 0; i < n; i++)
{
if (temp != -1)
{
rand = new Random(i * temp * ((int)DateTime.Now.Ticks));
}
int t = rand.Next(CharArray.Length - 1);
if (temp != -1 && temp == t)
{
return CreateRandomCode(n);
}
temp = t;
randomCode += CharArray[t];
}
return randomCode;
}
public void CreateCodeImage(string checkCode, HttpContext context)
{
int iwidth = (int)(checkCode.Length * 13);
System.Drawing.Bitmap image = new System.Drawing.Bitmap(iwidth, 20);
Graphics g = Graphics.FromImage(image);
Font f = new System.Drawing.Font("Arial", 12, (System.Drawing.FontStyle.Italic | System.Drawing.FontStyle.Bold));
// 前景色
Brush b = new System.Drawing.SolidBrush(Color.Black);
// 背景色
g.Clear(Color.White);
// 填充文字
g.DrawString(checkCode, f, b, 0, 1);
// 随机线条
Pen linePen = new Pen(Color.Gray, 0);
Random rand = new Random();
for (int i = 0; i < 5; i++)
{
int x1 = rand.Next(image.Width);
int y1 = rand.Next(image.Height);
int x2 = rand.Next(image.Width);
int y2 = rand.Next(image.Height);
g.DrawLine(linePen, x1, y1, x2, y2);
}
// 随机点
for (int i = 0; i < 30; i++)
{
int x = rand.Next(image.Width);
int y = rand.Next(image.Height);
image.SetPixel(x, y, Color.Gray);
}
// 边框
g.DrawRectangle(new Pen(Color.Gray), 0, 0, image.Width - 1, image.Height - 1);
// 输出图片
System.IO.MemoryStream ms = new System.IO.MemoryStream();
image.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
context.Response.ClearContent();
context.Response.ContentType = "image/jpeg";
context.Response.BinaryWrite(ms.ToArray());
g.Dispose();
image.Dispose();
}
}封装成类库：ValidateNumber.cs
using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Drawing; using System.Web.UI; using System.Drawing.Drawing2D; using System.IO; using System.Drawing.Imaging; //////ValidateNumber 生成验证码 /// public class ValidateNumber { //产生验证码的字符集 （易混淆的字符去掉） private string charcode = "2,3,4,5,6,8,9,A,B,C,D,E,F,G,H,J,K,M,N,P,R,S,U,W,X,Y,a,b,c,d,e,f,g,h,j,k,m,n,p,r,s,u,w,x,y"; ////// 验证码的最大长度 /// public int MaxLength { get { return 10; } } ////// 验证码的最小长度 /// public int MinLength { get { return 1; } } ////// 生成验证码 /// /// 指定验证码的长度 ///public string CreateValidateNumber(int length) { string[] CharArray = charcode.Split(',');//将字符串转换为字符数组 string randomCode = ""; int temp = -1; Random rand = new Random(); for (int i = 0; i < length; i++) { if (temp != -1) { rand = new Random(i * temp * ((int)DateTime.Now.Ticks)); } int t = rand.Next(CharArray.Length - 1); if (temp != -1 && temp == t) { return CreateValidateNumber(length); } temp = t; randomCode += CharArray[t]; } return randomCode; } /// /// 创建验证码的图片 /// /// context对象 /// 验证码 public void CreateValidateGraphic(HttpContext context,string validateNum) { int iwidth = (int)(validateNum.Length * 14); Bitmap image = new Bitmap(iwidth, 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); //画图片的干扰线 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 Font("Arial", 12, (FontStyle.Bold | FontStyle.Italic)); LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height), Color.Blue, Color.DarkRed, 1.2f, true); g.DrawString(validateNum, font, brush, 3, 2); //画图片的前景干扰点 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); //保存图片数据 MemoryStream stream = new MemoryStream(); image.Save(stream, ImageFormat.Jpeg); //输出图片 context.Response.Clear(); context.Response.ContentType = "image/jpeg"; context.Response.BinaryWrite(stream.ToArray()); } finally { g.Dispose(); image.Dispose(); } } ////// 得到验证码图片的长度 /// /// 验证码的长度 ///public static int GetImageWidth(int validateNumLength) { return (int)(validateNumLength * 14); } /// /// 得到验证码图片的高度 /// ///public static double GetImageHeight() { return 22; } }
