.net验证码小例子

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

public partial class mb_yanzhengma_log : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {

    }
    protected void Button1_Click(object sender, EventArgs e)
    {
        

        string usercode = txtcode.Text.Trim();
        if (usercode == Session["vcode"].ToString())//Session["vcode"]
        {
            Response.Write("OK,正确");
        }
        else
        {
            Response.Write("验证码不符合");
        }
    }
    
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Drawing;
using System.Drawing.Imaging;

public partial class mb_yanzhengma_ValidateCode : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        string validateCode = CreateValidateCode();//生成验证码 
        Bitmap bitmap = new Bitmap(imgWidth, imgHeight);//生成Bitmap图像 
        DisturbBitmap(bitmap); //图像背景 
        DrewValidateCode(bitmap, validateCode);//绘制验证码图像 
        bitmap.Save(Response.OutputStream, ImageFormat.Gif);//保存图像，等待输出
    }
    private int codeLen = 4;//验证码长度 
    private int fineness = 85;//图片清晰度 
    private int imgWidth = 48;//图片宽度 
    private int imgHeight = 24;//图片高度 
    private string fOntFamily= "Times New Roman";//字体名称 
    private int fOntSize= 14;//字体大小 
    //private int fOntStyle= 0;//字体样式 
    private int posX = 0;//绘制起始坐标X 
    private int posY = 0;//绘制坐标Y 
    private string CreateValidateCode() //生成验证码 
    {
        string validateCode = "";
        Random random = new Random();// 随机数对象 
        for (int i = 0; i