本文主要是介绍简单的Ajax验证用户名，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
jsp页面：
<%@ 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="${pageContext.request.contextPath }/scripts/jquery.js"></script>
<script type="text/javascript">$(function(){$(":input[name='username']").change(function(){var val = $(this).val();val = $.trim(val);if(val!=""){var url = "${pageContext.request.contextPath }/valiateUserName";//Servlet获得的参数名为userNamevar 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><div id="message"></div><br><input type="submit" value="Submit"/> </form></body>
</html>servlet:
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 ValiateUserName*/
@WebServlet("/valiateUserName")
public class ValiateUserName extends HttpServlet {private static final long serialVersionUID = 1L;/*** @see HttpServlet#HttpServlet()*/public ValiateUserName() {super();// 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 stubresponse.getWriter().append("Served at: ").append(request.getContextPath());}/*** @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)*/protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {List<String> userNames = Arrays.asList("aaa","bbb","ccc");String result = null;String username = request.getParameter("userName");if(userNames.contains(username)){result = "<font color='red'>该用户已经被使用</font>";}else{result = "<font color='green'>该用户可以使用</font>";}response.setContentType("text/html;charset=utf-8");response.setCharacterEncoding("utf-8");response.getWriter().print(result);}}
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