<%@ 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>
<script type="text/javascript">
var xmlHttp;
//创建Ajax核心对象XMLHttpRequest
function createXMLHttp(){
if(window.XMLHttpRequest){
xmlHttp = new XMLHttpRequest();
}else{
xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
}
}
function checkUsername(username){
createXMLHttp();
//设置请求方式为GET,设置请求的URL,设置为异步提交
xmlHttp.open("GET","CheckServlet?username="+username,true);
//将方法地址复制给onreadystatechange属性
//类似于
电话号码
xmlHttp.onreadystatechange = checkUsernameCallback();
//将设置信息发送到Ajax引擎
xmlHttp.send(null);
}
function checkUsernameCallback(){
//Ajax引擎状态为成功
if(xmlHttp.readyState == 4){
//HTTP协议状态为成功
if(xmlHttp.status == 200){
var text = xmlHttp.responseText;
if(text == "true"){
document.getElementById("msg").innerHTML = "此用户名已存在,无法使用!";
}else{
document.getElementById("msg").innerHTML = "此用户名可以使用";
}
}
}
}
</script>
</head>
<body>
<form action="regist.jsp" method="
post">
用户名:<input type="text" name="username" onblur="checkUsername(this.value)"><span id="msg"></span><br/>
密 码:<input type="password" name="password"><br/>
<input type="submit" value="注册">
<input type="reset" value="重置">
</form>
</body>
</html>