c#生成随机彩色验证码例子

c#生成随机彩色验证码例子

<table>
<tr>
<td style="text-align: right; height: 40px; width: 100px;">
<asp:TextBox ID="txtCheckCode" runat="server" Height="25px" Width="97px" ValidationGroup="1"></asp:TextBox>
</td>
<td style="text-align: center; height: 40px; width: 100px;">
<img id="chkCode" src="CheckCode.aspx" onclick="javascript:CheckCode();" style="cursor: pointer" />
</td>
<td>
 
<asp:RequiredFieldValidator ID="RequiredFieldValidator2" runat="server" ControlToValidate="txtCheckCode"
ErrorMessage="请输入验证码！" ForeColor="Red" ValidationGroup="1"></asp:RequiredFieldValidator>
</td>
<td>
<asp:Button  ID="btn" Text="登陆" runat="server" onclick="btn_Click" ValidationGroup="1" Style="height: 20px" />
<asp:Label ID="zt" ForeColor="Red" runat="server"></asp:Label>
</td>
</tr>
</table>

<script language="javascript" type="text/javascript" src="./Scripts/jquery-1.4.1.min.js"></script>
<script language="javascript" type="text/javascript">
function CheckCode() {
$("#chkCode").attr("src", "./CheckCode.aspx?" + Math.random());
}
</script>

protected void btn_Click(object sender, EventArgs e)
{
string checkCode =txtCheckCode.Text.Trim();
string ischeck = Session["UserCCode"].ToString();
if (!string.IsNullOrEmpty(checkCode)
&& ischeck.Equals(checkCode))
{
this.zt.Text = "登陆成功！";
}
else
{
this.zt.Text = "登陆失败！";
}
}

using System;
using System.Collections;
using System.Configuration;
using System.Data;
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;

public partial class CheckCode : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
this.CreateCheckCodeImage(GenerateCheckCode());
}

private string GenerateCheckCode()
{
int number;
char code;
string checkCode = String.Empty;

Random random = new Random();

for (int i = 0; i < 5; i++)
{
number = random.Next();

if (number % 2 == 0)
code = (char)('0' + (char)(number % 10));
else
code = (char)('A' + (char)(number % 26));

checkCode += code.ToString();
}
//Response.Cookies.Add(new HttpCookie("CheckCode", checkCode));
Session["UserCCode"] = checkCode;
return checkCode;
}

private void CreateCheckCodeImage(string checkCode)
{
if (checkCode == null || checkCode.Trim() == String.Empty)
return;

System.Drawing.Bitmap image = new System.Drawing.Bitmap((int)Math.Ceiling((checkCode.Length * 14.5)), 26);
Graphics g = Graphics.FromImage(image);
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
for (int 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("Arial", 13, (System.Drawing.FontStyle.Bold | System.Drawing.FontStyle.Italic));
System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height), Color.Blue, Color.DarkTurquoise, 1.2f, true);
g.DrawString(checkCode, font, brush, 6, 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);

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());
}
finally
{
g.Dispose();
image.Dispose();
}
}
}