C#生成验证码

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December 10

using System;
using System.IO;
using System.Drawing;
using System.Drawing.Imaging;
using System.Text;
using System.Collections;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
/**/
/// <summary>
///
/// ** asp.net(C#) 生成验证码 **
///
/// </summary>
public partial class CheckCode : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        string chkCode = string.Empty;
        //颜色列表，用于验证码、噪线、噪点
        Color[] color = { Color.Black, Color.Red, Color.Blue, Color.Green, Color.Orange, Color.Brown, Color.Brown, Color.DarkBlue };
        //字体列表，用于验证码
        string[] font = { "Times New Roman", "MS Mincho", "Book Antiqua", "Gungsuh", "PMingLiU", "Impact" };
        //验证码的字符集，去掉了一些容易混淆的字符
        char[] character = {'1', '2', '3', '4', '5', '6', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'J', 'K', 'L', 'M', 'N', 'P', 'R', 'S', 'T', 'U','V','W', 'X', 'Y' };
        Random rnd = new Random();
        //生成验证码字符串
        for (int i = 0; i < 4; i++)
        {
            chkCode += character[rnd.Next(character.Length)];
        }
        //写入Session
        HttpContext.Current.Session["CheckCode"] = chkCode;

        Bitmap bmp = new Bitmap(100, 40);
        Graphics g = Graphics.FromImage(bmp);
        g.Clear(Color.White);
        //画噪线
        for (int i = 0; i < 10; i++)
        {
            int x1 = rnd.Next(100);
            int y1 = rnd.Next(40);
            int x2 = rnd.Next(100);
            int y2 = rnd.Next(40);
            Color clr = color[rnd.Next(color.Length)];
            g.DrawLine(new Pen(clr), x1, y1, x2, y2);
        }
        //画验证码字符串
        for (int i = 0; i < chkCode.Length; i++)
        {
            string fnt = font[rnd.Next(font.Length)];
            Font ft = new Font(fnt, 18);
            Color clr = color[rnd.Next(color.Length)];
            g.DrawString(chkCode[i].ToString(), ft, new SolidBrush(clr), (float)i * 20 + 8, (float)8);
        }
        //画噪点
        for (int i = 0; i < 100; i++)
        {
            int x = rnd.Next(bmp.Width);
            int y = rnd.Next(bmp.Height);
            Color clr = color[rnd.Next(color.Length)];
            bmp.SetPixel(x, y, clr);
        }
        //清除该页输出缓存，设置该页无缓存
        Response.Buffer = true;
        Response.ExpiresAbsolute = System.DateTime.Now.AddMilliseconds(0);
        Response.Expires = 0;
        Response.CacheControl = "no-cache";
        Response.AppendHeader("Pragma", "No-Cache");
        //将验证码图片写入内存流，并将其以 "image/Png" 格式输出
        MemoryStream ms = new MemoryStream();
        try
        {
            bmp.Save(ms, ImageFormat.Png);
            Response.ClearContent();
            Response.ContentType = "image/Png";
            Response.BinaryWrite(ms.ToArray());
            Response.End();
        }
        finally
        {
            //显式释放资源
            bmp.Dispose();
            g.Dispose();
        }
    }
}

//<%@ Page Language="C#" AutoEventWireup="true" CodeFile="CheckCode.aspx.cs" Inherits="CheckCode" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

2:14 PM | Blog it | C#

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