asp.net實現簡單數字驗證碼執行個體

調用

驗證碼：<input type="text" id="txtValidate" style="border: solid 1px #9B9B9B; width: 85px;                        height: 17px;" />  <img src="Rnd.aspx" mce_src="Rnd.aspx" style="width: 58px; height: 17px;                            border: solid 1px #9B9B9B" align="absmiddle" />

後台實現
Rnd.aspx.cs

using System;using System.Collections;using System.Configuration;using System.Data;using System.Web;using System.Web.Security;using System.Web.UI;using System.Web.UI.HtmlControls;using System.Web.UI.WebControls;using System.Web.UI.WebControls.WebParts;using System.Drawing;using System.Drawing.Imaging;public partial class Rnd : System.Web.UI.Page{    private int codeLen = 5;//隨機顯示字元個數    private int fineness = 100;//圖片清晰度    private int imgWidth = 65;//圖片寬度    private int imgHeight = 20;//圖片高度    private string fontFamily = "Roman";//字型名稱    private int fontSize = 12; //字型大小    private Random random = new Random();    protected void Page_Load(object sender, EventArgs e)    {        string validateCode = CreateValidateCode();        Session["RandomNumber"] = validateCode;        Bitmap bitmap = new Bitmap(imgWidth, imgHeight);        DisturbBitmap(bitmap);        DrawValidateCode(bitmap, validateCode);        bitmap.Save(Response.OutputStream, ImageFormat.Gif);    }    private string CreateValidateCode()//得到隨機數    {        string validateCode = "";        for (int i = 0; i < codeLen; i++)        {            int n = random.Next(10);//返回一個小於最大值得隨機數            validateCode += n.ToString();        }        return validateCode;    }    private void DisturbBitmap(Bitmap bitmap)//擷取背景圖    {        for (int i = 0; i < bitmap.Width; i++)        {            for (int j = 0; j < bitmap.Height; j++)            {                if (random.Next(90) <= this.fineness)                {                    bitmap.SetPixel(i, j, Color.White);//擷取指定位置的像素顏色                }            }        }    }    private void DrawValidateCode(Bitmap bitmap, string validateCode)    {        Graphics g = Graphics.FromImage(bitmap);        Font font = new Font(fontFamily, fontSize, FontStyle.Bold);        g.DrawString(validateCode, font, Brushes.Green, random.Next(-3, 11), random.Next(-4, 1));//在指定地區繪製文本字元    }}