前端之家收集整理的这篇文章主要介绍了
Ajax_典型应用_验证用户名是否，
前端之家小编觉得挺不错的，现在分享给大家，也给大家做个参考。
<%@ 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" src="${pageContext.request.contextPath}/js/jquery-1.7.2.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}/valiateUserName";
var args={"userName":val,"time":new Date()};
$.post(url,args,function(data){
$("#message").html(data);
});
}
});
});
</script>
</head>
<body>
<form action="" method="post">
UserName:<input type="text" name="username"/>
<br/><br/>
<div id="message"></div>
<input type="submit" value="Submit"/>
</form>
</body>
</html>
package org.java.test;
import java.io.IOException;
import java.util.Arrays;
import java.util.List;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class ValiateUserNameServlet
*/
@WebServlet("/valiateUserName")
public class ValiateUserNameServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* Default constructor.
*/
public ValiateUserNameServlet() {
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request,HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request,HttpServletResponse response) throws ServletException,IOException {
// TODO Auto-generated method stub
response.getWriter().append("Served at: ").append(request.getContextPath());
}
/**
* @see HttpServlet#doPost(HttpServletRequest request,HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request,IOException {
List<String> userNames=Arrays.asList("AAA","BBB","CCC");
String userName=request.getParameter("userName");
String result=null;
if(userNames.contains(userName)){
result="<font color='red'>aleady used</font>";
}else{
result="<font color='green'>可以使用</font>";
}
response.setContentType("text/html;charset=UTF-8");
response.setCharacterEncoding("UTF-8");
response.getWriter().print(result);
}
}
原文链接：https://www.f2er.com/ajax/161519.html
