后台代码：
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.IO;
using System.Text;
namespace 验证码
{
public partial class pic : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
System.Drawing.Image img = new Bitmap(150, 50);
Graphics g = Graphics.FromImage(img);
this.AddPoint(img, 100);
string code = this.GeneralCode();
Font font1=new Font("宋体",30,FontStyle.Italic);
g.DrawString(code, font1, Brushes.Red, 0, 0);
this.Response.Clear();
MemoryStream ms = new MemoryStream();//创建一个缓存流
img.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);//将此图像以指定的格式保存到指定的流中
this.Response.BinaryWrite(ms.ToArray());
this.Response.Flush();//输出流
this.Response.End();//关闭流
}
private void AddPoint(System.Drawing.Image img, int nums)//加噪点
{
Bitmap b = img as Bitmap;
Random ran = new Random();
for (int i = 0; i < nums; i++)
{
b.SetPixel(ran.Next(0, img.Width), ran.Next(0, img.Height), Color.White);
}
}
//随即生成数字
private string GeneralCode()
{
Random ran = new Random(DateTime.Now.Millisecond);
StringBuilder sb = new StringBuilder(6);
for (int i = 0; i < 6; i++)
{
sb.Append(ran.Next(0, 9));
}
return sb.ToString();
}
}
}
