本文实例讲述了C#验证码的创建与使用方法。分享给大家供大家参考，具体如下：
1、C#创建验证码
① 创建获取验证码页面（ValidateCode.aspx）
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<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title>获取验证码</title>
</head>
<body>
<form id="form1" runat="server">
<div>获取验证码</div>
</form>
</body>
</html>
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② 编写获取验证码代码（ValidateCode.aspx.cs）
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/// <summary>
/// 验证码类型(0-字母数字混合,1-数字,2-字母)
/// </summary>
private string validateCodeType = "0";
/// <summary>
/// 验证码字符个数
/// </summary>
private int validateCodeCount = 4;
/// <summary>
/// 验证码的字符集，去掉了一些容易混淆的字符
/// </summary>
char[] character = { '2', '3', '4', '5', '6', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'J', 'K', 'L', 'M', 'N', 'P', 'R', 'S', 'T', 'W', 'X', 'Y' };
protected void Page_Load(object sender, EventArgs e)
{
//取消缓存
Response.BufferOutput = true;
Response.Cache.SetExpires(DateTime.Now.AddMilliseconds(-1));
Response.Cache.SetCacheability(System.Web.HttpCacheability.NoCache);
Response.AppendHeader("Pragma", "No-Cache");
//获取设置参数
if (!string.IsNullOrEmpty(Request.QueryString["validateCodeType"]))
{
validateCodeType = Request.QueryString["validateCodeType"];
}
if (!string.IsNullOrEmpty(Request.QueryString["validateCodeCount"]))
{
int.TryParse(Request.QueryString["validateCodeCount"], out validateCodeCount);
}
//生成验证码
this.CreateCheckCodeImage(GenerateCheckCode());
}
private string GenerateCheckCode()
{
char code ;
string checkCode = String.Empty;
System.Random random = new Random();
for (int i = 0; i < validateCodeCount; i++)
{
code = character[random.Next(character.Length)];
// 要求全为数字或字母
if (validateCodeType == "1")
{
if ((int)code < 48 || (int)code > 57)
{
i--;
continue;
}
}
else if (validateCodeType == "2")
{
if ((int)code < 65 || (int)code > 90)
{
i--;
continue;
}
}
checkCode += code;
}
Response.Cookies.Add(new System.Web.HttpCookie("CheckCode", checkCode));
this.Session["CheckCode"] = 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*15.0+40)), 23);
System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(image);
try
{
//生成随机生成器
Random random = new Random();
//清空图片背景色
g.Clear(System.Drawing.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 System.Drawing.Pen(System.Drawing.Color.Silver), x1, y1, x2, y2);
}
System.Drawing.Font font = new System.Drawing.Font("Arial", 14, (System.Drawing.FontStyle.Bold | System.Drawing.FontStyle.Italic));
System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush(new System.Drawing.Rectangle(0, 0, image.Width, image.Height), System.Drawing.Color.Blue, System.Drawing.Color.DarkRed, 1.2f, true);
int cySpace = 16;
for (int i = 0; i < validateCodeCount; i++)
{
g.DrawString(checkCode.Substring(i, 1), font, brush, (i + 1) * cySpace, 1);
}
//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, System.Drawing.Color.FromArgb(random.Next()));
}
//画图片的边框线
g.DrawRectangle(new System.Drawing.Pen(System.Drawing.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();
}
}
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2、验证码的使用
① 验证码的前段显示代码
复制代码 代码如下:
<img src="/ValidateCode.aspx?ValidateCodeType=1&0.011150883024061309" onclick="this.src='/ValidateCode.aspx?ValidateCodeType=1&'+Math.random();" id="imgValidateCode" csharp" id="highlighter_239683">
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<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title>验证码测试</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<input runat="server" id="txtValidate" />
<img src="/ValidateCode.aspx?ValidateCodeType=1&0.011150883024061309" onclick="this.src='/ValidateCode.aspx?ValidateCodeType=1&'+Math.random();" id="imgValidateCode" alt="点击刷新验证码" title="点击刷新验证码" style="cursor: pointer;">
<asp:Button runat="server" id="btnVal" Text="提交" onclick="btnVal_Click" />
</div>
</form>
</body>
</html>
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