简单的实现用ajax检测后台用户名是否存在
servlet
package com.demo.web;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class CheckNameServlet extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String name = request.getParameter("name");
System.out.println(name);
String flag = "0";
if("alex".equals(name)) {
flag = "1";
}
response.getWriter().write(flag);
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}
jsp
<%@ 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">
<script type="text/javascript"
src="${pageContext.request.contextPath }/js/jquery-1.11.3.min.js"></script>
<script type="text/javascript">
function checkName(obj) {
var name = obj.value;
$.ajax({
type : 'post',
url : '${pageContext.request.contextPath}/checkNameServlet',
data : {
'name' : name,
},
dataType : 'text',
success : function(data) {
if(data == 1){
//存在
$('#ret-msg').html("用户已存在");
}else{
//不存在
$('#ret-msg').html("");
}
// window.console.log('成功回调函数');
},
error : function() {
window.console.log('失败回调函数');
}
})
}
</script>
<title>ajax checkName</title>
</head>
<body>
<input type="text" name='name' id='name' onblur="checkName(this);"><span id='ret-msg'></span>
</body>
</html>