<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
<script src="js/jquery-3.2.1.min.js"></script>
<script>
$(function () {
$("#username").blur(function () {
var val = $(this).val();
// alert(val);
$.post("jsonLoginCheckServlet",{"username":val},function (data) {
//alert(data.userExsit);
if(data.userExsit){
var check = $("#usernameCheck");
check.html(data.msg).css("color","red");
}else{
var check = $("#usernameCheck");
check.html(data.msg).css("color","green");
}
});
});
});
</script>
</head>
<body>
<input type="text" id="username"><span id="usernameCheck"></span><br>
<input type="password" id="password"><br>
<input type="submit" value="登陆">
</body>
</html>
Servlet
response.setCharacterEncoding("utf-8");
response.setContentType("application/json; charset=UTF-8");
String username = request.getParameter("username");
System.out.println(username);
ObjectMapper objectMapper=new ObjectMapper();
Map<String,Object>map=new HashMap<String,Object>();
if("tom".equals(username)){
map.put("userExsit",true);
map.put("msg","用户名被使用");
// objectMapper.writeValue(response.getOutputStream(),map);
}else{
map.put("userExsit",false);
map.put("msg","验证通过");
//objectMapper.writeValue(response.getOutputStream(),map);
}
String data = objectMapper.writeValueAsString(map);
System.out.println(data);
response.getWriter().write(data);