本文實例講述了jsp+ajax實現的局部刷新較驗驗證碼(onblur事件觸發較驗)。分享給大家供大家參考，具體如下：
前台顯示頁面:
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>修改個人信息</title>
<script>
function createXMLHttpRequest() {
//表示當前浏覽器不是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) {
//創建XMLHttpRequest
createXMLHttpRequest();
var url = "codevalidate.jsp?authcode=" + field.value + "×tamp=" + new Date().getTime();//加時間戳防止緩存重復
xmlHttp.open("GET", url, true);
//方法地址，處理完成後自動調用，回調
xmlHttp.onreadystatechange=function() { //匿名函數
if(xmlHttp.readyState == 4) { //Ajax引擎初始化成功
if (xmlHttp.status == 200) { //http協議成功
document.getElementById("divbid").innerHTML =xmlHttp.responseText;
}else {
alert("請求失敗，錯誤碼=" + xmlHttp.status);
}
}
};
//將參數發送到Ajax引擎
xmlHttp.send(null);
}else {
div.innerHTML="<div class=\"wrong\">驗證碼不能為空</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">
輸入驗證碼：<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>
產生圖片頁面
authcode.jsp
<%@ page contentType="image/JPEG"
import="java.awt.*,java.awt.image.*,java.util.*,javax.imageio.*"
pageEncoding="GBK"%>
<%!Color getRandColor(int fc, int bc) {//給定范圍獲得隨機顏色
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);
}%>
<%
//設置頁面不緩存
response.setHeader("Pragma", "No-cache");
response.setHeader("Cache-Control", "no-cache");
response.setDateHeader("Expires", 0);
// 在內存中創建圖象
int width = 60, height = 20;
BufferedImage image = new BufferedImage(width, height,
BufferedImage.TYPE_INT_RGB);
// 獲取圖形上下文
Graphics g = image.getGraphics();
//生成隨機類
Random random = new Random();
// 設定背景色
g.setColor(getRandColor(200, 250));
g.fillRect(0, 0, width, height);
//設定字體
g.setFont(new Font("Times New Roman", Font.PLAIN, 18));
//畫邊框
//g.setColor(new Color());
//g.drawRect(0,0,width-1,height-1);
// 隨機產生155條干擾線，使圖象中的認證碼不易被其它程序探測到
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);
}
// 取隨機產生的認證碼(4位數字)
String sRand = "";
for (int i = 0; i < 4; i++) {
String rand = String.valueOf(random.nextInt(10));
sRand += rand;
// 將認證碼顯示到圖象中
g.setColor(new Color(20 + random.nextInt(110), 20 + random
.nextInt(110), 20 + random.nextInt(110)));//調用函數出來的顏色相同，可能是因為種子太接近，所以只能直接生成
g.drawString(rand, 13 * i + 6, 16);
System.out.println(rand);
}
// 將認證碼存入SESSION
session.setAttribute("code", sRand);
// 圖象生效
g.dispose();
// 輸出圖象到頁面
ImageIO.write(image, "JPEG", response.getOutputStream());
%>
ajax動態驗證頁面
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'>驗證碼不正確</div>");}
%>
希望本文所述對大家JSP程序設計有所幫助。
