字母+数字验证码
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.Drawing;
/// <summary>
/// 字母+数字验证码
/// </summary>
public partial class ValidateCode : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
// 在此处放置用户代码以初始化页面
CreateCheckCodeImage(GenerateCheckCode());
}
/// <summary>
/// 产生随机数
/// </summary>
/// <returns></returns>
private string GenerateCheckCode()
{
int number;
string strCode = string.Empty;
//随机种子
Random random = new Random();
for (int i = 0; i < 4; i++) //验证码长度为4
{
//随机整数
number = random.Next();
//字符从0-9,A-Z中产生,对应的ASCII码为48-57,65-90
number = number % 36;
if (number < 10)
{
number += 48;
}
else
{
number += 55;
}
strCode += ((char)number).ToString();
}
//将字符串保存在Cookies
Response.Cookies.Add(new HttpCookie("CheckCode", strCode));
return strCode;
}
/// <summary>
/// 生成图片
/// </summary>
/// <param name="checkCode">随机数</param>
private void CreateCheckCodeImage(string checkCode)
{
//若检验码为空,则直接返回
if (checkCode == null || checkCode.Trim() == string.Empty)
return;
//根据验证码长度确定输出图片的长度
System.Drawing.Bitmap image = new System.Drawing.Bitmap(Convert.ToInt32(Math.Ceiling(Convert.ToDecimal(checkCode.Length) * 15)), 20);
//创建Graphics对象
System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(image);
//生成随机数种子
Random random = new Random();
//清除图片背景颜色
g.Clear(Color.White);
//画背景图片的噪音线10条
for (int i = 0; i < 10; i++)
{
//噪音线起点坐标(x1,y1),终点坐标(x2,y2)
int x1 = random.Next(image.Width);
int x2 = random.Next(image.Width);
int y1 = random.Next(image.Height);
int y2 = random.Next(image.Height);
//用银色线画出噪音线
g.DrawLine(new Pen(Color.Silver), x1, y1, x2, y2);
}
//输出图片中校验码的字体:12号Arial,粗斜体
Font font = new Font("Arial", 12, FontStyle.Bold | FontStyle.Italic);
//线性渐变画刷
System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Width), Color.Blue, Color.Purple, 1.2f, true);
g.DrawString(checkCode, font, brush, 2, 2);
//画图片的前景噪点50个
for (int i = 0; i < 50; i++)
{
int x = random.Next(image.Width);
int y = random.Next(image.Height);
image.SetPixel(x, y, Color.FromArgb(random.Next()));
}
//画图片段边框线
g.DrawRectangle(new Pen(Color.SaddleBrown), 0, 0, image.Width - 1, image.Height - 1);
//创建内存流用于输出图片
System.IO.MemoryStream ms = new System.IO.MemoryStream();
//图片格式指定为png
image.Save(ms, System.Drawing.Imaging.ImageFormat.Png);
//清除缓冲区流中的所有输出
Response.ClearContent();
//输出流的Http Mime类型设置为"image/Png"
Response.ContentType = "image/Png";
//输出图片的二进制流
Response.BinaryWrite(ms.ToArray());
//释放Bitmap和Graphics对象
g.Dispose();
image.Dispose();
}
}