js
/**从b * */ var code ; //在全局定义验证码 //产生验证码 window.onload = function createCode(){ code = ""; var codeLength = 4;//验证码的长度 var checkCode = document.getElementById("code"); var random = new Array(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‘);//随机数 for(var i = 0; i < codeLength; i++) {//循环操作 var index = Math.floor(Math.random()*36);//取得随机数的索引（0~35） code += random[index];//根据索引取得随机数加到code上 } checkCode.value = code;//把code值赋给验证码 } //校验验证码 function validate(){ var inputCode = document.getElementById("input").value.toUpperCase(); //取得输入的验证码并转化为大写 if(inputCode.length <= 0) { //若输入的验证码长度为0 alert("请输入验证码！"); //则弹出请输入验证码 } else if(inputCode != code ) { //若输入的验证码与产生的验证码不一致时 alert("验证码输入错误！@_@"); //则弹出验证码输入错误 createCode();//刷新验证码 document.getElementById("input").value = "";//清空文本框 } else { //输入正确时 alert("^-^"); //弹出^-^ } }
html代码
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>Insert title here</title> <title>验证码</title> <style type="text/css"> #code { font-family:Arial; font-style:italic; font-weight:bold; border:0; letter-spacing:2px; color:blue; } </style> <script type = "text/javascript" src = "js/checkCode.js"> </script> </head> <body> <div> <input type = "text" id = "input"/> <input type = "button" id="code" onclick="createCode()"/> <input type = "button" value = "验证" onclick = "validate()"/> <a href="" onclick="createCode()">刷新</a> </div> </body> </html>
原文：http://www.cnblogs.com/5858y/p/7472084.html