本文实例讲述了jsp+ajax实现的局部刷新较验验证码(onblur事件触发较验)。分享给大家供大家参考，具体如下：
前台显示页面:
welcome.jsp
<%@ 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>
产生图片页面
authcode.jsp
<%@ 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());
%>
ajax动态验证页面
codevalidate.jsp
<%@ 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>");}
%>
希望本文所述对大家jsp程序设计有所帮助。
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