jsp ajax未刷新文本框信息验证 （登陆）
文件结构：
Ajax.js
var req;
function zz(){
alert("hello");
}
function validate() {
//获取表单提交的内容
var idField = document.getElementById("userName");
//访问validate.do这个servlet，同时把获取的表单内容idField加入url字符串，以便传递给validate.do
var url = "validate.do?id=" + escape(idField.value);
//创建一个XMLHttpRequest对象req
if(window.XMLHttpRequest) {
//IE7, Firefox, Opera支持
req = new XMLHttpRequest();
}else if(window.ActiveXObject) {
//IE5,IE6支持
req = new ActiveXObject("Microsoft.XMLHTTP");
}
/*
open(String method,String url, boolean )函数有3个参数
method参数指定向servlet发送请求所使用的方法，有GET,POST等
boolean值指定是否异步，true为使用，false为不使用。
我们使用异步才能体会到Ajax强大的异步功能。
*/
req.open("GET", url, true);
//onreadystatechange属性存有处理服务器响应的函数,有5个取值分别代表不同状态
req.onreadystatechange = callback;
//send函数发送请求
req.send(null);
}
function callback() {
if(req.readyState == 4 && req.status == 200) {
var check = req.responseText;
show (check);
}
}
function show(str) {
if(str == "OK") {
var show = "<font color='green'>恭喜！！用户名可用！</font>";
document.getElementById("info").innerHTML = show;
}
else if( str == "NO") {
var show = "<font color='red'>对不起，用户名不可用！！请重新输入！</font>";
document.getElementById("info").innerHTML = show;
}
}
index.jsp
<%@page contentType="text/html" pageEncoding="gb2312"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html>
<head>
<script type="text/javascript" src="Ajax.js"></script>
</head>
<body>
<h1>Test Ajax</h1><p>
<form action="" method="get" name="form">
<br>
输入用户名：
<input type="text" size="10" maxlength="8" id="userName" name="name" onblur="validate()">
<span id="info"></span>
<br>
输入商品名：
<input type="text" size="10" maxlength="8" >
</form>
<input type="button" onclick="zz()" />
</body>
</html>
DoAjaxServlet.java
package com.zxl;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class DoAjaxServlet extends HttpServlet {
protected void processRequest(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=gb2312");
PrintWriter out = response.getWriter();
try {
response.setContentType("text/html");
response.setHeader("Cache-Control", "no-store");
response.setHeader("Pragma", "no-cache");
response.setDateHeader("Expires", 0);
String name = request.getParameter("id");
if(name.equals("1")) {
out.write("OK");
}
else {
out.write("NO");
}
} finally {
out.close();
}
}
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
processRequest(request, response);
}
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
processRequest(request, response);
}
@Override
public String getServletInfo() {
return "Short description";
}
}