一般处理程序生成验证码

using System;
using System.Collections;
using System.Collections.Generic;
using System.Drawing;
using System.Drawing.Imaging;
using System.Linq;
using System.Web;
using System.Web.SessionState;
namespace XXX.Service
{
public class WaterMark : IHttpHandler, IRequiresSessionState  // 要使用session必须实现该接口,记得要导入System.Web.SessionState命名空间
{
public void ProcessRequest(HttpContext context)
{
string checkCode = GenCode(5);  // 产生5位随机字符
context.Session["Code"] = checkCode; //将字符串保存到Session中，以便需要时进行验证
System.Drawing.Bitmap image = new System.Drawing.Bitmap(80, 30);
Graphics g = Graphics.FromImage(image);
System.IO.MemoryStream ms = new System.IO.MemoryStream();
try
{
//生成随机生成器
Random random = new Random();
//清空图片背景色
g.Clear(Color.White);
// 画图片的背景噪音线
int i;
for (i = 0; i < 25; i++)
{
int x1 = random.Next(image.Width);
int x2 = random.Next(image.Width);
int y1 = random.Next(image.Height);
int y2 = random.Next(image.Height);
g.DrawLine(new Pen(Color.Silver), x1, y1, x2, y2);
}
Font font = new System.Drawing.Font("微软雅黑", 12, (System.Drawing.FontStyle.Bold));
System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height), Color.Blue, Color.DarkRed, 1.2F, true);
g.DrawString(checkCode, font, brush, 2, 2);
//画图片的前景噪音点
g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);
image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);
}
finally
{
g.Dispose();
image.Dispose();
}
context.Response.ClearContent();
context.Response.ContentType = "image/jpeg";
context.Response.BinaryWrite(ms.ToArray());
context.Response.AddHeader("Access-Control-Allow-Origin", "*");
}
/// <summary>
/// 产生随机字符串
/// </summary>
/// <param name="num">随机出几个字符</param>
/// <returns>随机出的字符串</returns>
private string GenCode(int num)
{
string str = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
char[] chastr = str.ToCharArray();
string code = "";
Random rd = new Random();
int i;
for (i = 0; i < num; i++)
{
code += str.Substring(rd.Next(0, str.Length), 1);
}
return code;
}
public bool IsReusable
{
get
{
return false;
}
}
}
}