验证码(C#) - .NET技术 / ASP.NET

using System;
using System.Configuration;
using System.IO;
using System.Collections;
using System.ComponentModel; using System.Data;
using System.Drawing;
using System.Web;
using System.Web.SessionState;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;

public partial class GetValidateCode : System.Web.UI.Page
{
    private void Page_Load(object sender, System.EventArgs e)
    {
        // 在此处放置用户代码以初始化页面
        Response.ClearContent();
        Response.ContentType = "images/Png";
        Response.BinaryWrite(GetVImageStream().ToArray());
    }


    #region 产生图片内存流
    /// <summary>
    /// 产生图片内存流
    /// </summary>
    /// <returns>图片内存流</returns>
    private MemoryStream GetVImageStream()
    {
        MemoryStream ImageMemoryStream = new MemoryStream();
        string VCodeString = GetVCode(4);
        ConfigurationManager.AppSettings["code"] = VCodeString;
        Font VCodeFont = new Font("Arial", 14, FontStyle.Bold);
        SolidBrush VCodeBrush = new SolidBrush(Color.SandyBrown);
        Pen LinePen = new Pen(Color.Ivory, 1);
        Bitmap Tmap = new Bitmap(VCodeString.Length * 19, 24);
        Graphics TGrphics;
        TGrphics = Graphics.FromImage(Tmap);
        TGrphics.Clear(BackGroundColor(200, 50));
        //产生干扰线
        for (int i = 1; i <= 6; i++)
        {
            int TmpPosition = i * 4;
            Color LineColor = BackGroundColor(100, 155);
            LinePen.Color = LineColor;
            TGrphics.DrawLine(LinePen, 0, TmpPosition, VCodeString.Length * 19, 0);
            LineColor = BackGroundColor(100, 155);
            LinePen.Color = LineColor;
            TGrphics.DrawLine(LinePen, 0, 24, VCodeString.Length * 19, TmpPosition);
        }
        //产生干扰线
        TGrphics.DrawString(VCodeString, VCodeFont, VCodeBrush, VCodeString.Length, 1);
        Tmap.Save(ImageMemoryStream, System.Drawing.Imaging.ImageFormat.Png);
        Tmap.Dispose();
        TGrphics.Dispose();
        return ImageMemoryStream;
    }
    #endregion

    #region 随机返回背景色
    /// <summary>
    /// 随机返回颜色
    /// </summary>
    /// <param name="BeginRandomNumber">指定颜色开始的最小值</param>
    /// <param name="RandomNumber">指定颜色值波动的范围</param>
    /// <returns>随机的Color</returns>
    private Color BackGroundColor(int BeginRandomNumber, int RandomNumber)
    {
        int ColorR = 0;
        int ColorG = 0;
        int ColorB = 0;
        Random TRandom = new Random();
        ColorR = BeginRandomNumber + TRandom.Next(RandomNumber);
        ColorG = BeginRandomNumber + TRandom.Next(RandomNumber);
        ColorB = BeginRandomNumber + TRandom.Next(RandomNumber);
        Color ColorBG = Color.FromArgb(ColorR, ColorG, ColorB);
        return ColorBG;
    }
    #endregion

    #region 随机产生字符串
    /// <summary>
    /// 随机产生字符串
    /// </summary>
    /// <param name="VCodeLength">要产生的随机字符串长度</param>
    /// <returns></returns>
    public string GetVCode(int VCodeLength)
    {
        if (VCodeLength <= 0)
        {
            return "";
        }
        string VCodeString = "0,1,2,3,4,5,6,7,8,9,a,b,c,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z,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[] VCodeStringArray = VCodeString.Split(',');
        string ReturnValue = "";
        int RandomNumber = 0;
        Random TRandom = new Random();
        for (int i = 1; i <= VCodeLength; i++)
        {
            RandomNumber = TRandom.Next(VCodeStringArray.Length);
            ReturnValue += VCodeStringArray[RandomNumber];
        }
        return ReturnValue;
    }
    #endregion

}