<%@ 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></title>
<script type="text/javascript" src="${pageContext.request.contextPath}/js/jquery-1.11.1.min.js"></script>
<script type="text/javascript">
$(function(){
$(":input[name=‘username‘]").change(function(){
var val = $(this).val();
val = $.trim(val);
if(val != ""){
var url = "${pageContext.request.contextPath}/validatUsername";
var args = {"username":val, "time":new Date()};
$.post(url, args, function(data){
$("#message").html(data);
});
}
});
})
</script>
</head>
<body>
<!--
1.导入JQuery库
2.获取name="username"的结点：username
3.1为username添加change响应函数。去除空格且不为空。准备发生Ajax请求。
3.2发送Ajax请求检验username是否可用
3.3在服务端返回一个html片段
3.4在客户端浏览器把其直接添加到#message的html中
-->
<form action="" method="post">
Username<input type="text" name="username"/><br/>
<div id="message"></div><br/>
<input type="submit" value="submit"/>
</form>
</body>
</html>
servlet
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
List<String> usernames = Arrays.asList("aaa","bbb","ccc");
String username = request.getParameter("username");
String result= null;
if (usernames.contains(username)) {
result = "<font color=‘red‘>该用户名已经被使用</font>";
}else{
result = "<font color=‘red‘>该用户名可以使用</font>";
}
response.setContentType("text/html;charset=UTF-8");
response.setCharacterEncoding("UTF-8");
response.getWriter().print(result);
}
时间： 2025-02-01 06:44:50