jsp+ajax实现的局部刷新较验验证码(onblur事件触发较验)

%@ page language="java" contentType="text/html; 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>修改个人信息/title>
script>
function createXMLHttpRequest() {
 //表示当前浏览器不是ie,如ns,firefox
 if(window.XMLHttpRequest) {
  xmlHttp = new XMLHttpRequest();
 } else if (window.ActiveXObject) {
  xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
 }
}
function validate(field) {
 var div=document.getElementById("divbid");
// var reg=/[^A-Za-z0-9_]{7,10}/g;
 if (field.value.length != 0) {
  //创建XMLHttpRequest
  createXMLHttpRequest();
  var url = "codevalidate.jsp?authcode=" + field.value + "×tamp=" + new Date().getTime();//加时间戳防止缓存重复
  xmlHttp.open("GET", url, true);
  //方法地址，处理完成后自动调用，回调
  xmlHttp.onreadystatechange=function() { //匿名函数
   if(xmlHttp.readyState == 4) { //Ajax引擎初始化成功
    if (xmlHttp.status == 200) { //http协议成功
     document.getElementById("divbid").innerHTML =xmlHttp.responseText;
    }else {
     alert("请求失败，错误码=" + xmlHttp.status);
    }
   }
  };
  //将参数发送到Ajax引擎
  xmlHttp.send(null);
 }else {
   div.innerHTML="div class=\"wrong\">验证码不能为空/div>"
 }
}
function reloadImage(imgurl){
 var getimagecode=document.getElementById("codeimg");
 getimagecode.src= imgurl + "?id=" + Math.random();
  var code=%=session.getAttribute("code")%>;
  alert(code)
}
/script>
/head>
body>
form action="authcode.jsp" method="post" name="loginform">
  输入验证码：input type="text" name="authcode" id="authcode" maxlength="4" size="10" onblur="validate(this)" >span id="divbid">/span>
  img id="codeimg" name="codeimg" border=0 src="authcode.jsp">
  a href="javascript:reloadImage('authcode.jsp')">看不清/a>br/>
/form>
script language="javascript" type="text/javascript">
function reloadImage(imgurl){
 var getimagecode=document.getElementById("codeimg");
 getimagecode.src= imgurl + "?id=" + Math.random();
 var code=%=session.getAttribute("code")%>;
 alert(code)
}
/script>
/body>
/html>

%@ page contentType="image/JPEG" 
 import="java.awt.*,java.awt.image.*,java.util.*,javax.imageio.*" 
 pageEncoding="GBK"%> 
%!Color getRandColor(int fc, int bc) {//给定范围获得随机颜色  
  Random random = new Random();  
  if (fc > 255)  
   fc = 255;  
  if (bc > 255)  
   bc = 255;  
  int r = fc + random.nextInt(bc - fc);  
  int g = fc + random.nextInt(bc - fc);  
  int b = fc + random.nextInt(bc - fc);  
  return new Color(r, g, b);  
 }%> 
%  
 //设置页面不缓存  
 response.setHeader("Pragma", "No-cache");  
 response.setHeader("Cache-Control", "no-cache");  
 response.setDateHeader("Expires", 0);  
 // 在内存中创建图象  
 int width = 60, height = 20;  
 BufferedImage image = new BufferedImage(width, height,  
   BufferedImage.TYPE_INT_RGB);  
 // 获取图形上下文  
 Graphics g = image.getGraphics();  
 //生成随机类  
 Random random = new Random();  
 // 设定背景色  
 g.setColor(getRandColor(200, 250));  
 g.fillRect(0, 0, width, height);  
 //设定字体  
 g.setFont(new Font("Times New Roman", Font.PLAIN, 18));  
 //画边框  
 //g.setColor(new Color());  
 //g.drawRect(0,0,width-1,height-1);  
 // 随机产生155条干扰线，使图象中的认证码不易被其它程序探测到  
 g.setColor(getRandColor(160, 200));  
 for (int i = 0; i  100; i++) {  
  int x = random.nextInt(width);  
  int y = random.nextInt(height);  
  int xl = random.nextInt(12);  
  int yl = random.nextInt(12);  
  g.drawLine(x, y, x + xl, y + yl);  
 }  
 // 取随机产生的认证码(4位数字)  
 String sRand = ""; 
 for (int i = 0; i  4; i++) {  
  String rand = String.valueOf(random.nextInt(10));  
  sRand += rand;  
  // 将认证码显示到图象中  
  g.setColor(new Color(20 + random.nextInt(110), 20 + random  
  .nextInt(110), 20 + random.nextInt(110)));//调用函数出来的颜色相同，可能是因为种子太接近，所以只能直接生成  
  g.drawString(rand, 13 * i + 6, 16);  
  System.out.println(rand); 
 }  
 // 将认证码存入SESSION  
 session.setAttribute("code", sRand);  
 // 图象生效  
 g.dispose();  
 // 输出图象到页面  
 ImageIO.write(image, "JPEG", response.getOutputStream());  
%>

%@ page language="java" import="java.util.*,java.util.*,java.text.*,com.neusoft.xkxt.dao.*,com.neusoft.xkxt.bean.*,com.neusoft.xkxt.util.*" pageEncoding="UTF-8"%> 
% 
String path = request.getContextPath(); 
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/"; 
%> 
% 
 String authcode=request.getParameter("authcode"); 
 String code=(String)session.getAttribute("code"); 
 if(authcode.equals(code)){ 
 out.println("div class='right'>√/div>");} 
 else{ 
 out.println("div class='wrong'>验证码不正确/div>");} 
%>