.NET常用类与方法——验证码生成方法
首先在html页面中加入javascript，此处注意imgNode.src必须根据情况自行修改。然后，新建一个“一般处理程序”，将WaterMark类的所有代码全部复制进去即可。
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title></title>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<script type="text/javascript">
function change() {
var imgNode = document.getElementById("vimg");
imgNode.src = "WaterMark.ashx?t=" + (new Date()).valueOf(); // 这里加个时间的参数是为了防止浏览器缓存的问题
}
</script>
</head>
<body>
<img src="WaterMark.ashx" id="vimg" alt="" onclick="change();"/>
</body>
</html>
<%@ WebHandler Language="C#" class="WaterMark" %>
using System;
using System.Web;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Web.SessionState;
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(70, 22);
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
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("Arial", 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);
System.IO.MemoryStream ms = new System.IO.MemoryStream();
image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);
context.Response.ClearContent();
context.Response.ContentType = "image/Gif";
context.Response.BinaryWrite(ms.ToArray());
}
finally
{
g.Dispose();
image.Dispose();
}
}
/// <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[] source ={ "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z", "#", "$", "%", "&", "@" };
string code = "";
Random rd = new Random();
int i;
for (i = 0; i < num; i++)
{
//code += source[rd.Next(0, source.Length)];
code += str.Substring(rd.Next(0, str.Length), 1);
}
return code;
}
public bool IsReusable
{
get
{
return false;
}
}
}
