ASP.ENT(C#) 条形码生成技术

using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Drawing;
using System.Drawing.Drawing2D;

public partial class ValidateNum : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            Response.BufferOutput = true;  //特别注意
            Response.Cache.SetExpires(DateTime.Now.AddMilliseconds(-1));//特别注意
            Response.Cache.SetCacheability(HttpCacheability.NoCache);//特别注意
            Response.AppendHeader("  Pragma", "No-Cache"); //特别注意

            string ValidateNum = CreateRandomNum(4);//生成4位随机数
            CreateImage(ValidateNum); //将生成的随机数绘成图片
            Session["ValidateNum"]=ValidateNum; //保存验证码
        }
    }
       
    //生成随机字符串
    private string CreateRandomNum(int NumCount)
    {
        //所有可能生成的验证码
        string allchar= "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,W,X,Y,Z";
        string[] allcharArray = allchar.Split(',');//拆分数组
        string RandomNum="";
        int temp=-1;//记录上次随机数的数值，尽量避免产生几个相同的随机数
        Random rand = new Random();
        for(int i=0;i
        {
            if(temp!=-1)
            {
                rand= new Random(i*temp*((int)DateTime.Now.Ticks));
            }
            int t= rand.Next(35);
            if(temp==t)
            {
                return CreateRandomNum(NumCount);
            }
            temp=t;
            RandomNum=RandomNum+allcharArray[t];
        }
        return RandomNum;
    }

    //生成图片
    private void CreateImage(string ValidateNum)
    {
        if(ValidateNum==null||ValidateNum.Trim()==String.Empty)
            return;
        System.Drawing.Bitmap image = new System.Drawing.Bitmap(ValidateNum.Length*12+10,22);
       Graphics g = Graphics.FromImage(image);
        try
        {
            Random rand = new Random();
            g.Clear(Color.White);  //清空图片背景色

            //画图片背景噪音线
            for(int i=0;i<100;i++)
            {
                int x1 = rand.Next(image.Width);
                int x2 = rand.Next(image.Width);
                int y1 = rand.Next(image.Height);
                int y2 = rand.Next(image.Height);
                g.DrawLine(new Pen(Color.Silver),x1,y1,x2,y2);
            }

            Font font = new Font("Arial",12,(FontStyle.Bold|FontStyle.Italic));
            LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(0,0,image.Width,image.Height),Color.Blue,Color.DarkRed,1.2f,true);
            g.DrawString(ValidateNum,font,brush,2,2);

            //画图片的前景噪音
            for(int i=0;i<100;i++)
            {
                int x=rand.Next(image.Width);
                int y=rand.Next(image.Height);
                image.SetPixel(x,y,Color.FromArgb(rand.Next()));
            }

            //画图片的边框线
            g.DrawRectangle(new Pen(Color.Silver),0,0,image.Width-1,image.Height-1);

            System.IO.MemoryStream ms = new System.IO.MemoryStream();
            //将图片保存到指定的流
            image.Save(ms,System.Drawing.Imaging.ImageFormat.Gif);
            Response.ClearContent();
            Response.ContentType="image/gif";
            Response.BinaryWrite(ms.ToArray());
        }
        catch(Exception e)
        {
            return;
        }
        finally
        {
            g.Dispose();
            image.Dispose();
        }
    }
}

 

说明：此段代码可单独放在一个页面ValidateNum.aspx中，其生成的验证码供图片标签引用