校檢碼頁面_生成圖片頁面

 using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Runtime.InteropServices;
using System.Drawing;
using System.Drawing.Text;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;
using System.Text;

public partial class yanzhen : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        string checkCode = GetRandCode(5);
        Session["CheckCode"] = checkCode;
        DrawImage(checkCode);

    }

     private string GetRandCode(int num)
    {
        string[] code = new string[] { "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z" };
        string vNum = "";
        Random ran = new Random();
        int iNum = 0;
        for (int i = 1; i <= num; i++)
        {
            //while((iNum = Convert.ToInt32(code.Length*ran.NextDouble())) == code.Length)
            //{
            //    iNum = Convert.ToInt32(code.Length*ran.NextDouble());
            //}
            iNum = ran.Next(0, code.Length);//哈哈 这句效率更高
            vNum += code[iNum];
        }
        return vNum;
    }

    private void DrawImage(string code)
    {
        Bitmap bp = new Bitmap(70, 25);
        Graphics ga = Graphics.FromImage(bp);
        ///设置画笔的输出模式
        ga.SmoothingMode = SmoothingMode.HighSpeed;

        Rectangle rc = new Rectangle(0, 0, 70, 25);//定义一个矩形
        ga.FillRectangle(new SolidBrush(Color.White), rc);//填充矩形
        ga.DrawString(code, new Font("宋体", 16), new SolidBrush(Color.Red), rc);//在矩形内画出字符串
        Response.ContentType = "image/jpeg";

        //保存数据流
        bp.Save(Response.OutputStream, ImageFormat.Jpeg);
        bp.Dispose();
        ga.Dispose();
    }
    }

 調用方法: Image1.ImageUrl = "yanzhen.aspx";

TBCheckCode.Text != Session["CheckCode"].ToString()