我有一个JSP页面，其中编写了用于注册页面和ajax调用的设计代码，以验证来自servlet的电子邮件地址。当我从servlet提取查询时，它表明该记录存在于db中，但是我无法在RegiserUSer.jsp页面上打印它，而是在servlet页面（Registration.java）上打印记录，但是我希望此消息应该可以在“提交”按钮下方的jsp页面上打印。
这是我的页面
RegisterUser.jsp
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="ISO-8859-1">
<title>Registration Page</title>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.1.2/css/bootstrap.min.css" integrity="sha384-Smlep5jCw/wG7hdkwQ/Z5nLIefveQRIY9nfy6xoR1uRYBtpZgI6339F5dgvm/e9B" crossorigin="anonymous">
<script src="https://code.jquery.com/jquery-3.3.1.slim.min.js" integrity="sha384-q8i/X+965DzO0rT7abK41JStQIAqVgRVzpbzo5smXKp4YfRvH+8abtTE1Pi6jizo" crossorigin="anonymous"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.3/umd/popper.min.js" integrity="sha384-ZMP7rVo3mIykV+2+9J3UJ46jBk0WLaUAdn689aCwoqbBJiSnjAK/l8WvCWPIPm49" crossorigin="anonymous"></script>
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.1.3/js/bootstrap.min.js" integrity="sha384-ChfqqxuZUCnJSK3+MXmPNIyE6ZbWh2IMqE241rYiqJxyMiZ6OW/JmZQ5stwEULTy" crossorigin="anonymous"></script>
</head>
<body class="mt-10">
<div class="m-auto text-center mt-5" style="margin: 10px 0 0 10px; width: 400px">
<form action="Registration" method="post" class="mt-5 border px-4 py-5" style="padding: 10px;" onsubmit="return validateForm()">
<h3>Member Signup</h3>
<table class="w-100">
<tbody>
<tr>
<td><input type="text" placeholder="create username"
name="username" class="form-control mt-2" /> <span
id="usernameErrorMsg" class="text-danger"></span></td>
</tr>
<tr></tr>
<tr>
<td><input type="text" placeholder="name" name="name"
class="form-control mt-2" /> <span id="nameErrorMsg"
class="text-danger"></span></td>
</tr>
<tr></tr>
<tr>
<td><input type="email" placeholder="email" name="email" id="email"
class="form-control mt-2"/> <span id="msg" class="text-danger"></span></td>
<!-- <span id="msg"></span> -->
</tr>
<tr></tr>
<tr>
<td><input type="tel" placeholder="mobile number"
name="mobile" class="form-control mt-2" /> <span
id="mobileErrorMsg" class="text-danger"></span></td>
</tr>
<tr></tr>
<tr>
<td><input type="password" placeholder="password" name="pwd"
class="form-control mt-2" /> <span id="pwdErrorMsg"
class="text-danger"></span></td>
</tr>
<tr></tr>
<tr>
<td><input type="password" placeholder="confirm password"
name="cpwd" class="form-control mb-2" /> <span id="cpwdErrorMsg"
class="text-danger"></span></td>
</tr>
<tr></tr>
</tbody>
<tr></tr>
</table>
<button type="submit" name="submit" class="btn btn-primary" id="formSubmit" >Register</button>
<button type="reset" name="cancel" class="btn btn-primary">Cancel</button>
<br /> Already Registered? <a href="Login.jsp" class="mb-2">Signin</a><br>
<div id="messageDiv" style="display:none;"></div>
</form>
</div>
<script>
$("#formSubmit").on('click', function(){
alert('test1');
debugger;
var xmlhttp = new XMLHttpRequest();
var email = $("#email").val();
alert(email);
var email1="?email=" + email
var url = "http://localhost:8080/MyWebProject/UserDetails/Registration";
alert(url);
debugger;
$.ajax({
type: "POST",
url : url,
data: "email="+ email,
success : function(results){
if(results != null && results != ""){
debugger;
showMessage(results);
$('#messageDiv').css("display","block");
}else{
debugger;
$('#messageDiv').css("display","none");
$('#messageDiv').html("");
alert("Some exception occurred! Please try again.");
}
},
error: function(jqxhr){
alert("error alert called");
debugger;
return false;
}
});
});
//function to display message to the user
function showMessage(results){
if(results == 'SUCCESS'){
$('#messageDiv').html("<font color='green'>Email Not Registered </font>")
}else if(results == 'FAILURE'){
$('#messageDiv').html("<font color='red'>Email Registered </font>")
}
}
</script>
</body>
</html>
RegistrationService.java
public class RegistrationService {
public String doLogin(String email) {
Connection con = null;
String message = null;
String query;
try {
con = DBConnection.connectDB();
query ="SELECT TOP 1 * FROM UserDetails WHERE email="+"'"+email+"'";
ResultSet rs =DBConnection.getDBResultSet(con, query);
if(rs.next()){
message = "SUCCESS";
}else{
message = "FAILURE";
}
}catch(Exception e) {
message = "FAILURE";
e.printStackTrace();
}
return message;
}
Registration.java
public class Registration extends HttpServlet {
boolean status;
String emailValue,resultData,success,fail;
PreparedStatement ps = null;
PrintWriter out ;
RegistrationService service = null;
public void init(ServletConfig config)throws ServletException{
service = new RegistrationService();
}
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
}
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
PrintWriter out = response.getWriter();
HttpSession session = request.getSession();
response.setContentType("text/html");
String userName = request.getParameter("username");
String name = request.getParameter("name");
String email = request.getParameter("email");
String phone = request.getParameter("mobile");
String password = request.getParameter("pwd");
String confirmPassword = request.getParameter("cpwd");
String message = service.doLogin(email);
response.getWriter().write(message);
}
}
现在，请提出如何打印成功和失败消息的信息，即分别在RegisterUser.jsp页面本身上打印“已注册电子邮件”和“未注册电子邮件”。
