爱华网下图为一个含有字母跟数字的简单验证码：
下面我们就来看看它们是如何产生的：
用一般处理程序生成验证码
[csharp] view plaincopyprint?
usingSystem;
usingSystem.Web;
usingSystem.Drawing;
usingSystem.Drawing.Drawing2D;
usingSystem.Web.SessionState;
namespaceWeb.handler
{
///<summary>
///WaterMark的摘要说明
///</summary>
publicclassWaterMark: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
{
publicvoidProcessRequest(HttpContextcontext)
{
stringcheckCode=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.Bitmapimage=newSystem.Drawing.Bitmap(70,22);
Graphicsg=Graphics.FromImage(image);
try
{
//生成随机生成器
Randomrandom=newRandom();
//清空图片背景色
g.Clear(Color.White);
//画图片的背景噪音线
inti;
for(i=0;i<25;i++)
{
intx1=random.Next(image.Width);
intx2=random.Next(image.Width);
inty1=random.Next(image.Height);
inty2=random.Next(image.Height);
g.DrawLine(newPen(Color.Silver),x1,y1,x2,y2);
}
Fontfont=newSystem.Drawing.Font("Arial",12,(System.Drawing.FontStyle.Bold));
System.Drawing.Drawing2D.LinearGradientBrushbrush=newSystem.Drawing.Drawing2D.LinearGradientBrush(newRectangle(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(newPen(Color.Silver),0,0,image.Width-1,image.Height-1);
System.IO.MemoryStreamms=newSystem.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>
///<paramname="num">随机出几个字符</param>
///<returns>随机出的字符串</returns>
privatestringGenCode(intnum)
{
//验证码中出现的字符
stringstr="0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";<SPAN></SPAN>//str中的值就是将来会在验证码中出现的字符
char[]chastr=str.ToCharArray();
stringcode="";
Randomrd=newRandom();
inti;
for(i=0;i<num;i++)
{
//code+=source[rd.Next(0,source.Length)];
code+=str.Substring(rd.Next(0,str.Length),1);
}
returncode;
}
publicboolIsReusable
{
get
{
returnfalse;
}
}
}
}
using System;using System.Web;using System.Drawing;using System.Drawing.Drawing2D;using System.Web.SessionState;namespace Web.handler{ /// <summary> /// WaterMark 的摘要说明 /// </summary> 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) { //验证码中出现的字符 string str = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";//str中的值就是将来会在验证码中出现的字符 char[] chastr = str.ToCharArray(); 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; } } }}
刷新验证码的HTML及Javascript代码：
[html] view plaincopyprint?
<%@PageLanguage="C#"AutoEventWireup="true"CodeBehind="Login.aspx.cs"Inherits="nwessystem.Login"%>
<!DOCTYPEhtmlPUBLIC"-//W3C//DTDXHTML1.0Transitional//EN""http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<htmlxmlns="http://www.w3.org/1999/xhtml">
<headrunat="server">
<title>登录窗体</title>
<linkhref="../css/login.css"rel="stylesheet"type="text/css"/>
<scriptlanguage="javascript"type="text/javascript">
//刷新验证码的js函数
functionchangeCode(){
varimgNode=document.getElementById("vimg");
//重新加载验证码，达到刷新的目的
imgNode.src="../handler/WaterMark.ashx?t="+(newDate()).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>
<p>验证码：<imgsrc="../handler/WaterMark.ashx"id="vimg"alt="点击刷新验证码"onclick="changeCode()"/><asp:TextBoxID="txtCode"runat="server"CssClass="txtcode"></asp:TextBox></p>
</body>
</html>
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Login.aspx.cs" Inherits="nwessystem.Login" %><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head runat="server"> <title>登录窗体</title> <link href="../css/login.css" rel="stylesheet" type="text/css" /> <script language="javascript" type="text/javascript"> //刷新验证码的js函数 function changeCode() { var imgNode = document.getElementById("vimg"); //重新加载验证码，达到刷新的目的 imgNode.src = "../handler/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> <p>验证码：<img src="../handler/WaterMark.ashx" id="vimg" alt="点击刷新验证码" onclick="changeCode() " /><asp:TextBox ID="txtCode" runat="server" CssClass="txtcode"></asp:TextBox></p> </body></html>
登录时判断验证码是否正确
[csharp] view plaincopyprint?
usingSystem;
usingSystem.Collections.Generic;
usingSystem.Linq;
usingSystem.Web;
usingSystem.Web.UI;
usingSystem.Web.UI.WebControls;
usingBLL;
namespacenwessystem
{
publicpartialclassLogin:System.Web.UI.Page
{
protectedvoidbtnLogin_Click(objectsender,EventArgse)
{
//检验验证码部分
stringcode=txtCode.Text.Trim().ToUpper();
stringrightCode=Session["Code"].ToString();
//判断验证码是否正确
if(code!=rightCode)
{
//验证码输入错误！
Page.ClientScript.RegisterStartupScript(Page.GetType(),"message","<scriptlanguage='javascript'defer>alert('验证码错误！');</script>");
return;
}
//检验用户名和密码部分
stringname=txtName.Text.Trim();
stringpwd=txtPassword.Text.Trim();
boolb=LoginManager.Login(name,pwd);
if(b)
{
//登录成功
Page.ClientScript.RegisterStartupScript(Page.GetType(),"message","<scriptlanguage='javascript'defer>alert('登录成功！');</script>");
}
else
{
//登录失败
Page.ClientScript.RegisterStartupScript(Page.GetType(),"message","<scriptlanguage='javascript'defer>alert('登录失败，用户名或密码错误！');</script>");
}
}
}
}
using System;using System.Collections.Generic;using System.Linq;using System.Web;using System.Web.UI;using System.Web.UI.WebControls;using BLL;namespace nwessystem{ public partial class Login : System.Web.UI.Page { protected void btnLogin_Click(object sender, EventArgs e) { //检验验证码部分 string code = txtCode.Text.Trim().ToUpper(); string rightCode = Session["Code"].ToString(); //判断验证码是否正确 if (code != rightCode) { //验证码输入错误！ Page.ClientScript.RegisterStartupScript(Page.GetType(), "message", "<script language='javascript' defer>alert('验证码错误！');</script>"); return; } //检验用户名和密码部分 string name=txtName.Text.Trim(); string pwd=txtPassword.Text.Trim(); bool b = LoginManager.Login(name, pwd); if (b) { //登录成功 Page.ClientScript.RegisterStartupScript(Page.GetType(), "message", "<script language='javascript' defer>alert('登录成功！');</script>"); } else { //登录失败 Page.ClientScript.RegisterStartupScript(Page.GetType(), "message", "<script language='javascript' defer>alert('登录失败，用户名或密码错误！');</script>"); } } }}
好了，通过上面简单的代码就可以实现验证码的生成与验证了。代码里注释很详细了，相信不用我再写多余的说明，大家也都可以看懂。如果还是不懂欢迎在下方留言。博客水平有限，希望各位多多指正！
