jsp代码
<%--
Created by IntelliJ IDEA.
User: 23369
Date: 2019/8/26
Time: 14:06
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" pageEncoding="UTF-8" %>
<html>
<head>
<title>Title</title>
<script type="text/javascript" src="jQuery/jquery-3.4.1.js"></script>
<script type="text/javascript">
$(function () {
$(":input[name='username']").change(function () {
var val = $(this).val();//获取值
val = $.trim(val);
if (val != ""){
var url = "${pageContext.request.contextpath}/SelectUserNameServlet";
var args = {"username":val,"time":new Date()};
$.post(url,args,function (data) {
$("#message").html(data);
});
}
});
});
</script>
</head>
<body>
<form action="${pageContext.request.contextpath}" method="post">
用户名<input id="username" type="text" name="username"><div id="message"> </div><br>
密码<input type="password" name="userpass"><div id="messagePassword"></div><br>
<input type="submit" name="submitInput" value="登录"><br>
</form>
</body>
</html>
java代码
package com.hern;
import javax.jws.WebService;
import javax.servlet.servletexception;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.Arrays;
import java.util.List;
@WebServlet(name = "/SelectUserNameServlet")
public class SelectUserNameServlet extends HttpServlet {
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws servletexception, IOException {
response.setContentType("text/html;charset=UTF-8");
response.setCharacterEncoding("UTF-8");
List<String> userNames = Arrays.asList("AAA","BBB","CCC");
String userName = request.getParameter("username");
String result = null;
if (userNames.contains(userName)){
result = "<font color='red'>该用户名已被使用</font>";
}else {
result = "<font color='red'>该用户名可以使用</font>";
}
response.getWriter().print(result);
}
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws servletexception, IOException {
}
}
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