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//写入IO流
System.IO.MemoryStream ms = new System.IO.MemoryStream();
image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);
Response.ClearContent();
Response.ContentType = "image/Gif";
Response.BinaryWrite(ms.ToArray()); <img id="IMG1" runat="server" src="checkcode.aspx" />using System;
using System.Data;
using System.Configuration;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;
using System.Drawing;
/// <summary>
///用于生成验证码和验证码图片,用于预防攻击。
/// </summary>
public class AuthCode:Page
{
public AuthCode()
{
CreateCheckCodeImage(GenerateCheckCode());
}
public string GenerateCheckCode()
{
int number;
char code;
string checkCode = String.Empty;
System.Random random = new Random();
for (int i = 0; i < 4; i++ )
{
number = random.Next();
if (number%2 != 0)
{
code = (char)('A' + (char)(number % 26));
}
else
{
code = (char)('0' + (char)(number % 10));
}
checkCode += code.ToString();
}
Session["checkCode"] = checkCode;
return checkCode;
}
public void CreateCheckCodeImage(string checkCode)
{
if(checkCode == null || checkCode.Trim()== String.Empty)
{
return;
}
System.Drawing.Bitmap image = new Bitmap((int)Math.Ceiling(checkCode.Length * 12.5), 22);
Graphics g = Graphics.FromImage(image);
try
{
//随机生成器
Random random = new Random();
//用白色清空图片
g.Clear(Color.White);
//画图片的背景噪音线
for (int i = 0; i < 2;i++ )
{
int x1 = random.Next(image.Width);
int y1 = random.Next(image.Height);
int x2 = random.Next(image.Width);
int y2 = random.Next(image.Height);
if (i == 1)
{
g.DrawLine(new Pen(Color.Black), x1, y1, x2, y2);
}
else
{
g.DrawLine(new Pen(Color.Blue), x1, y1, x2, y2);
}
}
//画验证码
Font font = new Font("Impact", 12, FontStyle.Italic);
System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height), Color.Green, Color.DarkRed, 1.2f, true);
g.DrawString(checkCode, font, brush, 2, 2);
//画图片的前景噪音点
for (int i = 0; i < 100; i++)
{
int x = random.Next(image.Width);
int y = random.Next(image.Height);
image.SetPixel(x, y, Color.FromArgb(random.Next()));
}
//画图片的边框线
g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);
//写入IO流
System.IO.MemoryStream ms = new System.IO.MemoryStream();
image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);
Response.ClearContent();
Response.ContentType = "image/Gif";
Response.BinaryWrite(ms.ToArray());
}
catch (System.Exception ex)
{
}
finally
{
}
}
}