--Servlet代码
package com.ajax.servlets;
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;
@WebServlet("/valiateUserName")
public class ValiateUserNameServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
protected void doPost(HttpServletRequest request,HttpServletResponse response) throws ServletException,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'>该用户已经存在</font>";
}else{
result="<font color='green'>该用户已经可以使用</font>";
}
response.setContentType("text/html;charset=UTF-8");
response.setCharacterEncoding("UTF-8");
response.getWriter().print(result);
}
}
jsp代码:
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<!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=ISO-8859-1">
<script type="text/javascript" src="${pageContext.request.contextPath}/scripts/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>
<title>Insert title here</title>
</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>