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Request method 'POST' not supported]

I have a problem with updatePowerPlant() method, when I try to update powerPlant entity with given id and click the submit button in the update form under localhost:8080/updatePowerPlant adress I get redirected to this url http://localhost:8080/updatePowerPlant/savePowerPlant.
I don't know why. I should get redireted to /powerPlants, wethever entity with given id exists or not, instead /savePowerPlant is added as a last part of a url localhost:8080/updatePowerPlant and I get Request method 'POST' not supported], I know that this is the message I should get afterall there is no GetController with such url but why do I get this weird url? Is it because I use GetController for update?
localhost:8080/updatePowerPlant this I enter in browser to get update form
http://localhost:8080/updatePowerPlant/savePowerPlant this I get when I clik submit in update form
Controller class
#RequiredArgsConstructor
#Controller
public class PowerPlantsController {
private final PowerPlantRepository powerPlantRepository;
private final EventRepository eventRepository;
private final PlantService plantService;
private final EventService eventService;
#GetMapping("form")
public String getForm(Model model) {
model.addAttribute("plant", new PlantViewModel());
return "save";
}
#PostMapping("savePowerPlant")
public String addPowerPlant(#ModelAttribute("plant") #Valid PlantViewModel plant, BindingResult bindingResult) {
if (bindingResult.hasErrors()) {
if (plant.getId() == null) {
return "save";
} else return "updatePowerPlant";
}
if (plant.getId() == null){
plantService.add(plant);
}else {
plantService.update(plant);
}
return "redirect:/powerPlants";
}
#GetMapping("updatePowerPlant/{id}")
public String updatePowerPlant(#PathVariable(value = "id") Integer id, Model model) {
var find = powerPlantRepository.getOne(id);
var plants = plantService.powerPlantToViewModel(find);
model.addAttribute("plant", plants);
return "updatePowerPlant";
}
#ResponseBody
#GetMapping("failures/{id}")
public long failures(#PathVariable("id") int id) {
return eventService.NumberOfFailureEventsForId(id);
}
#ResponseBody
#GetMapping("powerPlants")
public List<PowerPlant> findAll() {
return powerPlantRepository.findAll();
}
#GetMapping("powerPlants/{id}")
public String findById(#PathVariable("id") Integer id, Model model) {
model.addAttribute("plant", powerPlantRepository.getOne(id));
return "plant";
}
#GetMapping("delete/powerPlants")
public String deleteById(#RequestParam(value = "id") Integer id) {
powerPlantRepository.deleteById(id);
return "redirect:/powerPlants";
}
#GetMapping("addEventToPlant")
public String addEventToPlant(#RequestParam(value = "plantId") Long plantId, #RequestParam(value = "eventId")
Long eventId, Model model) {
if (powerPlantRepository.findById(Math.toIntExact(plantId)).isPresent()
&& eventRepository.findById(Math.toIntExact(eventId)).isPresent()) {
var pl = powerPlantRepository.getOne(Math.toIntExact(plantId));
var ev = eventRepository.getOne(Math.toIntExact(eventId));
var eventsForPlant = pl.getEvents();
eventsForPlant.add(ev);
pl.setEvents(eventsForPlant);
powerPlantRepository.save(pl);
}
var t = powerPlantRepository.getOne(Math.toIntExact(plantId)).getEvents();
model.addAttribute("plant", t);
return "plant_events";
}
}
Service class
#org.springframework.stereotype.Service
#RequiredArgsConstructor
public class PlantService implements powerForPowerPlantPerDay, Add, PlantServiceToViewModel {
private final EventRepository eventRepository;
private final PowerPlantRepository powerPlantRepository;
public Map<Integer, String> powerForPowerPlantPerDay(Timestamp date) {
List<Event> list = new ArrayList<>(getAllEvents());
Map<Integer, String> map = new HashMap<>();
list.stream()
.filter(e -> e.startDate.equals(date))
.forEach(e -> map.put(e.id, e.typeOfEvent));
return map;
}
public Collection<Event> getAllEvents() {
return eventRepository.findAll();
}
public void add(PlantViewModel plantViewModel) {
var p = PowerPlant.builder().
name(plantViewModel.getName())
.power(plantViewModel.getPower())
.events(plantViewModel.getListOfEventsForPlant())
.build();
powerPlantRepository.save(p);
}
public PlantViewModel powerPlantToViewModel(PowerPlant powerPlant) {
return PlantViewModel.builder()
.id(powerPlant.getId())
.name(powerPlant.getName())
.power(powerPlant.getPower())
.build();
}
public PowerPlant update(PlantViewModel plantViewModel) {
var plant = powerPlantRepository.getOne(plantViewModel.getId());
plant.setName(plantViewModel.getName());
plant.setPower(plantViewModel.getPower());
return powerPlantRepository.save(plant);
}
}
update html
<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.w3.org/1999/xhtml">
<head>
<meta charset="UTF-8">
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.1.3/css/bootstrap.min.css"/>
</head>
<body>
<div class="container">
<h1>Update</h1>
<hr>
<h2>Update powerPlant</h2>
<form action="#" th:action="#{savePowerPlant}" th:object="${plant}" method="POST">
<input id="studentId" th:value="${plant.id}" type="hidden" th:field="*{id}">
<div th:if="${#fields.hasErrors('name')}" th:errors="*{name}">Invalid Name</div>
<input type="text" th:field="*{name}" placeholder="Name" class="form-control mb-4 col-4">
<div th:if="${#fields.hasErrors('power')}" th:errors="*{power}">Invalid power</div>
<input type="text" th:field="*{power}" placeholder="power" class="form-control mb-4 col-4">
<button type="submit" class="btn btn-info col-2">Save</button>
</form>
<hr>
</div>
</body>
</html>
save html
<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.w3.org/1999/xhtml">
<head>
<meta charset="UTF-8">
<title>New Student</title>
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.1.3/css/bootstrap.min.css"/>
</head>
<body>
<div class="container">
<h1>Save</h1>
<hr>
<h2>Save powerPlant</h2>
<form action="#" th:action="#{savePowerPlant}" th:object="${plant}" method="POST">
<div th:if="${#fields.hasErrors('name')}" th:errors="*{name}">Invalid Name</div>
<input type="text" th:field="*{name}" placeholder="Name" class="form-control mb-4 col-4">
<div th:if="${#fields.hasErrors('power')}" th:errors="*{power}">Invalid power</div>
<input type="text" th:field="*{power}" placeholder="power" class="form-control mb-4 col-4">
<button type="submit" class="btn btn-info col-2">Save</button>
</form>
<hr>
</div>
</body>
</html>

As you can see here in the documentation you are using relative URLs in your th:action. These get appended to the current URL in the address bar.
So th:action="#{savePowerPlant}" results in current/URL/savePowerPlant.
Simple solution is to switch to absolute URLs either by typing it out completely (http://localhost:portNumber/savePowerPlant) or perhaps even better use server relative URL: th:href="#{~/savePowerPlant}.

Spring thymeleaf give error in post request

I have this simple code: This is my controller class where i redirecting to a page
#Controller
public class SimpleController {
#GetMapping("/nuovo-utente")
public String viewInserisciUtente(Model model){
model.addAttribute("nuovoUtente", new Utente());
return "nuovo-utente";
}
#PostMapping("/nuovo-utente")
public void memorizzaUtente(#ModelAttribute Utente utente){
System.out.println(utente.getId());
}
}
This is model class.
public class Utente {
private String id=null;
private String citta=null;
private String genere=null;
private String data_nascita=null;
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getCitta() {
return citta;
}
public void setCitta(String citta) {
this.citta = citta;
}
public String getGenere() {
return genere;
}
public void setGenere(String genere) {
this.genere = genere;
}
public String getData_nascita() {
return data_nascita;
}
public void setData_nascita(String data_nascita) {
this.data_nascita = data_nascita;
}
}
and My html page with thymeleaf is like :
<!DOCTYPE HTML>
<html xmlns:th="http://www.thymeleaf.org">
<head>
<title>Inserisci un nuovo utente</title>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
</head>
<body>
<h1>Form</h1>
<form action="#" th:action="#{/nuovo-utente}" th:object="${nuovoUtente}" method="post">
<p>Id: <input type="text" th:field="*{id}" /></p>
<p>Città: <input type="text" th:field="*{citta}" /></p>
<p>Genere: <input type="text" th:field="*{genere}" /></p>
<p>Data nascita: <input type="text" th:field="*{data_nascita}" /></p>
<p><input type="submit" value="Submit" /> <input type="reset" value="Reset" /></p>
</form>
</body>
</html>
So, as I said into the title, this simple code for a form give me error when I try to submit the form by post request. The error is the above:
Error during execution of processor 'org.thymeleaf.spring5.processor.SpringInputGeneralFieldTagProcessor' (template: "nuovo-utente" - line 10, col 32)
What can you say to me? Some help will be appreciate

You have to use diferent html and urls. One to create the form and another one to submit the form. You are using the same url.

First of all in your html page change
<html xmlns:th="http://www.thymeleaf.org">
to
<html xmlns:th="http://www.w3.org/1999/xhtml">
And write your controller class like
#PostMapping("/nuovo-utente")
public String memorizzaUtente(#ModelAttribute("nuovoUtente") Utente utente) {
System.out.println(utente.getId());
return "any page";
}
}

passing value to a jsp page from a java class using DAO

I wanted to pass the value retrieved on a java class to a page.I am using DAO classes.
I have retrieved the values from the database and stored them on String variables.Now I want to set them to the text boxes in my view.jsp page.I am new to this area,can anyone help me out??
View.jsp is as
<%# 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">
<title>Insert title here</title>
</head>
<body>
<form action="process.jsp">
Enter Name <br/> <br> <input type="text" name="uname" onclick="this.value=''"/><br/><br/>
<input type="submit" value="view details"/><br/><br/>
Email id: <br/> <input type="text" name="email" id="email" > <br/><br/>
password: <br/> <input type="text" name="passw" id="passw"><br/><br/>
</form>
</body>
</html>
and My Activity ViewDAO.java is as
public static void view(user u) {
Connection con=ConnectionProvider.getCon();
String uname=u.getUname();
try {
PreparedStatement ps=con.prepareStatement("select email,pass from S1.USER432 where name='"+uname+"'");
ResultSet rs = ps.executeQuery();
while (rs.next()) {
String email = rs.getString("EMAIL");
String pass = rs.getString("PASS");
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
Thanks...

If you are using a front controller[spring mvc] then you can pass the data by doing,
model.addAttribute("variable_name ", data);
and in the jsp you can access it by doing this ${variable_name};

You need to call the DAO method from your servlet like below:
public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// call DAO method to get the email and password
HashMap<String,String> map=ViewDAO.getDetails();
//from the map you will get the email and password.then you need to set them in the attributes and get them in your jsp
request.setAttribute("email", map.get("email"));
request.setAttribute("password", map.get("password"));
}
your DAO method should be like the below:
public static HashMap<String,String> getDetails(user u) {
Connection con=ConnectionProvider.getCon();
String uname=u.getUname();
Map<String,String> map=new HashMap<>();
try {
PreparedStatement ps=con.prepareStatement("select email,pass from S1.USER432 where name='"+uname+"'");
ResultSet rs = ps.executeQuery();
while (rs.next()) {
String email = rs.getString("EMAIL");
String pass = rs.getString("PASS");
}
map.put("email",email);
map.put("password",pass);
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return map;
}
}
Hope this will help you.

if you are using simple jsp and servelt, then make one ViewController.java.
You can two methods one for handling GET and other for POST
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
try {
String email = request.getParameter("email");
String password = request.getParameter("password");
request.setAttribute("email", email);
request.setAttribute("password", password);
request.getRequestDispatcher("view.jsp").forward(request, response);
}
catch(Exception e){
}
View.jsp
<%# 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">
<title>Insert title here</title>
</head>
<body>
<form action="process.jsp">
Enter Name <br/> <br> <input type="text" name="uname" onclick="this.value=''"/><br/><br/>
<input type="submit" value="view details"/><br/><br/>
Email id: <br/> <input type="text" name="email" id="email" value="<%=email%>" > <br/><br/>
password: <br/> <input type="text" name="passw" id="passw" value="<%=password%>"><br/><br/>
</form>
</body>
</html>

The Servlet decides which page must be loaded. So whatever you get from the DAO must go to the Servlet and through that, to the jsp. You can use a bean class to send values from DAO to Servlet.
Like this,
public class Details{
private String email;
private String password;
public void setEmail(String email){
this.email = email;
}
public void setPassword(String password){
this.password= password;
}
public String getEmail(){
return this.email;
}
public String getPassword(){
return this.password;
}
}
And you can make the following changes in DAO after getting the query results in the String. Add these
Details d = new Details();
d.setEmail(email);
d.setPassword(pass);
return d;
You can pass this object d to the servlet and retrieve the values using the getter methods of the bean. Also, the DAO must be called from the Servlet.
And now on the Servlet side.
On the Servlet you can put your code in the get or post method depending on your need. It may be like
public class ExampleServlet extends HttpServlet{
protected void doPost(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
String email = request.getParameter("email"); //got from the jsp where "email" is the name attribute of the input field
Details d = new Details();
d = ViewDao.view(user_object); //the bean sent by DAO. "user_object" is parameter that your DAO method is taking in your code
if(d.getEmail()!=null){ //just an example
// your code that redirects desired page
}
}
}
Based on d returned by the DAO you may redirect to any page you want.

Something like that
Observe this import
dao.UserDao,bean.*,
dao is the package
UserDao is the class
bean is the method you want or is could an attribute from dao
remember that
jsp
<body>
<%#page import="dao.UserDao,bean.*,java.util.*"%>
<%# taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<h1>Users List</h1>
<%
List<User> list=UserDao.getAllRecords();
request.setAttribute("list",list);
%>
<div class="table-responsive">
<table class="table">
<thread class="bg-info">
<th>Id</th><th>Name</th><th>Password</th><th>Edit</th><th>Delete</th>
</thread>
<c:forEach items="${list}" var="u">
<tr>
<td>${u.getId()}</td><td>${u.getUsername()}</td><td>${u.getPassword()}</td>
<td>Edit</td>
<td>Delete</td>
</tr>
</c:forEach>
</table>
</div>
<br/>Add New User
<br>
<br>
<form action="index.jsp">
<button type="submit">IndexUsers</button>
</form>
</body>
Bean or model
package bean;
// classe para as tables
public class User {
private int id;
private String username,password;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
}
dao
public class UserDao {
public static Connection getConnection(){
Connection con=null;
try{
Class.forName("com.mysql.cj.jdbc.Driver");
con=DriverManager.getConnection("jdbc:mysql://localhost:3306/mysql_database","root","14570");
}catch(Exception e){System.out.println(e);}
return con;
}
public static int save(User u){
int status=0;
try{
Connection con=getConnection();
PreparedStatement ps=con.prepareStatement(
"insert into login(username,password) values(?,?)");
ps.setString(1,u.getUsername());
ps.setString(2,u.getPassword());
status=ps.executeUpdate();
}catch(Exception e){System.out.println(e);}
return status;
}
public static int update(User u){
int status=0;
try{
Connection con=getConnection();
PreparedStatement ps=con.prepareStatement(
"update login set username=?,password=? where id=?");
ps.setString(1,u.getUsername());
ps.setString(2,u.getPassword());
ps.setInt(3,u.getId());
status=ps.executeUpdate();
}catch(Exception e){System.out.println(e);}
return status;
}
public static int delete(User u){
int status=0;
try{
Connection con=getConnection();
PreparedStatement ps=con.prepareStatement("delete from login where id=?");
ps.setInt(1,u.getId());
status=ps.executeUpdate();
}catch(Exception e){System.out.println(e);}
return status;
}
public static List<User> getAllRecords(){
List<User> list=new ArrayList<User>();
try{
Connection con=getConnection();
PreparedStatement ps=con.prepareStatement("select * from login");
ResultSet rs=ps.executeQuery();
while(rs.next()){
User u=new User();
u.setId(rs.getInt("id"));
u.setUsername(rs.getString("username"));
u.setPassword(rs.getString("password"));
list.add(u);
}
}catch(Exception e){System.out.println(e);}
return list;
}
public static User getRecordById(int id){
User u=null;
try{
Connection con=getConnection();
PreparedStatement ps=con.prepareStatement("select * from login where id=?");
ps.setInt(1,id);
ResultSet rs=ps.executeQuery();
while(rs.next()){
u=new User();
u.setId(rs.getInt("id"));
u.setUsername(rs.getString("username"));
u.setPassword(rs.getString("password"));
}
}catch(Exception e){System.out.println(e);}
return u;
}
}

Another Example this import import="dao.*"% makes available any methods from package dao, Bellow you see how to get the result of the method countid() in the dao.
<%#page import="dao.*"%>
<%#page import="java.sql.DriverManager"%>
<%#page import="java.sql.ResultSet"%>
<%#page import="java.sql.Connection"%>
<%#page contentType="text/html" pageEncoding="UTF-8"%>
<% int id = 0; %>
<%
DaoEvento daoEvento = new DaoEvento();
id = daoEvento.countId();
%>
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>JSP Page</title>
</head>
<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bootstrap#4.6.1/dist/css/bootstrap.min.css" integrity="sha384-zCbKRCUGaJDkqS1kPbPd7TveP5iyJE0EjAuZQTgFLD2ylzuqKfdKlfG/eSrtxUkn" crossorigin="anonymous">
<body>
<br><br>
<form action="add_event_servletnew" method="POST">
<div class="form-group">
<td>
<font color='green' face = "Arial" size = "4">
<%= request.getParameter("message") %>
</font>
view
<td>
</div>
<div class="form-group">
<label>id</label>
<input type="text" name="id" value="<%= id%>" readonly="readonly" class="form-control"/>
</div>
<div class="form-group">
<label>Title</label>
<input type="text" name="title" value="" class="form-control" />
</div>
<div class="form-group">
<label>Start</label>
<input type="date" name="start" value="" class="form-control"/>
</div>
<div class="form-group">
<label>End</label>
<input type="date" name="end" value="" class="form-control" />
</div>
<div class="form-group">
<td><input type="submit" value="submit" class="btn btn-success btn-block"/></td>
</div>
</form>
</body>
<script src="https://cdn.jsdelivr.net/npm/jquery#3.5.1/dist/jquery.slim.min.js" integrity="sha384-DfXdz2htPH0lsSSs5nCTpuj/zy4C+OGpamoFVy38MVBnE+IbbVYUew+OrCXaRkfj" crossorigin="anonymous"></script>
<script src="https://cdn.jsdelivr.net/npm/bootstrap#4.6.1/dist/js/bootstrap.bundle.min.js" integrity="sha384-fQybjgWLrvvRgtW6bFlB7jaZrFsaBXjsOMm/tB9LTS58ONXgqbR9W8oWht/amnpF" crossorigin="anonymous"></script>
<script src="jquery.mask.min.js"> </script>
</html>

When I try to get value from Java class to JSP, my JSP shows "nul"

I am till a learner in Java, please help me out. Here is my sample code, when I execute this program. It should retrieve info from the data base and store the values in the Java class and there by send the value to JSP but when i look at JSP it shows value "null"
Here are the 5 files related to my problem, any answers or solutions are happily accepted.
-------------------------this my basic input form---------------------------
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>WELCOME TO DISCOUNTLOVERS.IN</title>
<script type="text/javascript" src="jquery-1.2.6.min.js"></script>
<link href="stylesheet.css" rel="stylesheet" type="text/css" />
</head>
<body>
<div id="wrapper">
<div><%#include file="header.jsp" %></div>
<div><table width="920" border="0" cellpadding="0" cellspacing="0" id="main-content" >
<form method ="post" action ="Registrationform" >
<tbody>
<tr>
<td width="382" valign="top" class="formtext">
<div>First Name</div>
<div>Last name</div>
<div>E-mail</div>
<div>Password</div>
<div>Confirm Password</div>
<div>phone no</div>
<div>Address</div>
<div>City</div>
<div>State</div>
<div>country</div>
<div>post code</div>
</td>
<td width="52" class="formtext-gap">
<div>:</div>
<div>:</div>
<div>:</div>
<div>:</div>
<div>:</div>
<div>:</div>
<div>:</div>
<div>:</div>
<div>:</div>
<div>:</div>
<div>:</div>
</td>
<td width="486" valign="top">
<div><input type="text" name="username_first"/></div>
<div><input type="text" name="username_last"/></div>
<div><input type="text" name="username_email"/></div>
<div><input type="text" name="username_pw"/></div>
<div><input type="text" name="username_cpw"/></div>
<div><input type="text" name="username_tele"/></div>
<div><input type="text" name="username_add"/></div>
<div><input type="text" name="username_city"/></div>
<div><input type="text" name="username_state"/></div>
<div><input type="text" name="username_country"/></div>
<div><input type="text" name="username_postcode"/></div>
</td>
</tr>
<tr><td colspan="3" align="center"><input type="checkbox"/> Terms and conditions of Discountlovers.in accpeted</td></tr>
<tr><td colspan="3" align="center"><div><input type="submit" value="Submit" class=""/></div></td></tr>
</tbody></form></table></div>
<div><%#include file="footer.jsp" %></div>
</div>
</body>
</html>
------------------------ this is data insertion servlet------------------------
package registration_Servlets;
import registration_Servlets.intialization_form;
import java.io.IOException;
import java.io.PrintWriter;
import java.sql.PreparedStatement;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class Registrationform
*/
#WebServlet("/Registrationform")
public class Registrationform extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* #see HttpServlet#HttpServlet()
*/
public Registrationform() {
super();
// TODO Auto-generated constructor stub
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setContentType("text/html");
PrintWriter pw = response.getWriter();
intialization_form obj = new intialization_form();
String name;
String lastname;
String username_email;
String username_pw ;
String username_cpw;
String id ;
String username_add;
String username_city ;
String username_state;
String username_country;
String username_postcode;
try {
name = request.getParameter("username_first");
lastname = request.getParameter("username_last");
username_email = request.getParameter("username_email");
username_pw = request.getParameter("username_pw");
username_cpw = request.getParameter("username_cpw");
id = request.getParameter("username_tele");
username_add = request.getParameter("username_add");
username_city = request.getParameter("username_city");
username_state = request.getParameter("username_state");
username_country = request.getParameter("username_country");
username_postcode = request.getParameter("username_postcode");
DataBase db = new DataBase();
PreparedStatement pst = db.getConnection().prepareStatement("insert into registrationinfo values(?,?,?,?,?,?,?,?,?,?,?)");
pst.setString(1, name );
pst.setString(2, lastname);
pst.setString(3, username_email);
pst.setString(4, username_pw);
pst.setString(5, username_cpw);
pst.setString(6, id);
pst.setString(7, username_add);
pst.setString(8, username_city);
pst.setString(9, username_state);
pst.setString(10, username_country);
pst.setString(11, username_postcode);
int i = pst.executeUpdate();
if(i==1){
//request.setAttribute("name",name);
/*String site = new String("Retrivin_user_reg_form");
response.setStatus(response.SC_MOVED_TEMPORARILY);
response.setHeader("Location", site); */
response.sendRedirect("Retrivin_user_reg_form");
}
pw.println("done");
}
catch (Exception e) {
e.printStackTrace();
}
}
}
--------------------------------this is my data retrieve servlet-----------------
package registration_Servlets;
import java.io.IOException;
import java.io.PrintWriter;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class Retrivin_user_reg_form
*/
#WebServlet("/Retrivin_user_reg_form")
public class Retrivin_user_reg_form extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* #see HttpServlet#HttpServlet()
*/
public Retrivin_user_reg_form() {
super();
// TODO Auto-generated constructor stub
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setContentType("text/html");
PrintWriter pw = response.getWriter();
try {
DataBase db = new DataBase();
PreparedStatement pst = db.getConnection().prepareStatement("Select * from registrationinfo");
intialization_form obj = new intialization_form();
ResultSet i = pst.executeQuery();
while(i.next()){
// pw.println("EmpName" + " " + "EmpSalary" + "<br>");
obj.name= i.getString(1);
obj.lastname=i.getString(2);
obj.username_email=i.getString(3);
obj.username_pw=i.getString(4);
obj.username_cpw=i.getString(5);
obj.id=i.getString(6);
obj.username_add=i.getString(7);
obj.username_city=i.getString(8);
obj.username_state=i.getString(9);
obj.username_country=i.getString(10);
obj.username_postcode=i.getString(11);
String site = new String("registrationcompleted.jsp");
response.setStatus(response.SC_MOVED_TEMPORARILY);
response.setHeader("Location", site);
/*request.getRequestDispatcher("registrationcompleted.jsp").forward(request, response);*/
}
}
catch (Exception e) {
e.printStackTrace();
}
}
protected void doPost(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {
}
}
-----------this is my Java class where i want to store my retrieved data--------------
package registration_Servlets;
public class intialization_form
{
String name;
String lastname;
String username_email;
String username_pw;
String username_cpw;
String id;
String username_add;
String username_city;
String username_state;
String username_country;
String username_postcode;
public void setname( String value )
{
name = value;
}
public String getname() { return name; }
public void setlastname( String value )
{
lastname = value;
}
public String getlastname() { return lastname; }
public void setusername_email( String value )
{
username_email = value;
}
public String getusername_email() { return username_email; }
public void setusername_pw(String value){
username_pw= value;
}
public String getusername_pw() { return username_pw; }
public void setusername_cpw(String value){
username_cpw=value;
}
public String getusername_cpw(){
return username_cpw;
}
public void setid(String value){
id= value;
}
public String getid(){
return id;
}
public void setusername_add(String value){
username_add= value;
}
public String getusername_add(){
return username_add;
}
public void setusername_city(String value){
username_city= value;
}
public String getusername_city(){
return username_city;
}
public void setusername_state(String value){
username_state= value;
}
public String getusername_state(){
return username_state;
}
public void setusername_country(String value){
username_country = value;
}
public String getusername_country(){
return username_country;
}
public void setusername_postcode(String value){
username_postcode= value;
}
public String getusername_postcode(){
return username_postcode;
}
}
-------------------------this is my out put JSP where I get null value-------------
<%# page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<%# page import = "registration_Servlets.intialization_form" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>WELCOME TO DISCOUNTLOVERS.IN</title>
<script type="text/javascript" src="jquery-1.2.6.min.js"></script>
<link href="stylesheet.css" rel="stylesheet" type="text/css" />
</head>
<body>
<div id="wrapper">
<div><%#include file="header.jsp" %></div>
<div><table width="920" border="0" cellpadding="0" cellspacing="0" id="main-content">
<tbody>
<tr>
<td>
<% intialization_form user = new intialization_form(); %>
first Name: <%= user.getname() %>
last name: <%= user.getlastname() %><BR>
Email: <%= user.getusername_email() %><BR>
</td>
</tr>
</tbody></table></div>
<div><%#include file="footer.jsp" %></div>
</div>
</body>
</html>

I can see you have used
request.getRequestDispatcher("registrationcompleted.jsp").forward(request, response);
before doing this add line given below before forward() method
request.setAttribute("your-key", yourObjectReference);
This method of request object will set your form object as an attribute which you want to access in your output jsp, which you can retrieve using request.getAttribute("key") method.
put below code in your output jsp.
<% intialization_form user = (intialization_form)request.getAttribute("your-key"); %>
since request.getAttribute() method returns Object you will have to cast it in intialization_form
And don't forget to remove below lines from your code before doing this
response.setStatus(response.SC_MOVED_TEMPORARILY);
response.setHeader("Location", site);

It is because the values in you form class are NULL. You never assign any values to them.
You just create an empty form object and the "print" some of its values.
<% intialization_form user = new intialization_form(); %>
first Name: <%= user.getname() %>
last name: <%= user.getlastname() %><BR>
Email: <%= user.getusername_email() %><BR>
#See https://stackoverflow.com/tags/servlets/info for some info how to start jsp and servlet programming.

Spring MVC and form binding : how to remove an item from a List?

I have a Person model attribute that contains a list of emails.
I've created some JavaScript code that deletes elements from an HTML list of emails. This is pure JavaScript client side code, no AJAX call.
After submitting, I don't understand why I get all the emails in the corresponding #Controller method, even the ones that were deleted in the HTML.
Can anyone please explain?
JSP
<%# taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%# taglib prefix="form" uri="http://www.springframework.org/tags/form" %>
<%# taglib prefix="fn" uri="http://java.sun.com/jsp/jstl/functions" %>
<%# taglib prefix="fmt" uri="http://java.sun.com/jsp/jstl/fmt" %>
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"></meta>
<link rel="stylesheet" href="<c:url value="/styles/resume.css"/>" type="text/css"></link>
<link href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8/themes/base/jquery-ui.css" rel="stylesheet" type="text/css"></link>
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.8/jquery.min.js"></script>
<script src="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8/jquery-ui.min.js"></script>
<script src="/resume/js/jquery.editable-1.0.1.js"></script>
<title>Resumes manager</title>
<script>
$(document).ready(function() {
$('.trash').click(function() {
$(this.parentNode).remove();
});
});
</script>
</head>
<body>
<h1>Personal data</h1>
<form:form modelAttribute="person" action="/resume/person/edit/save" id="personForm" method="post" >
<table>
<tr>
<td>Email addresses:</td>
<td colspan="4">
<ol id="emails">
<c:forEach items="${person.emails}" varStatus="status">
<li><form:hidden path="emails[${status.index}].order" class="emailsDisplayOrder"></form:hidden><form:input path="emails[${status.index}].label"></form:input><form:input type="email" path="emails[${status.index}].value"></form:input><input type="image" src="/resume/images/trash.png" class="trash" value="${status.index}"></input></li>
</c:forEach>
</ol>
</td>
</tr>
</table>
</form:form>
</body>
</html>
Controller
#Controller
#SessionAttributes(types={Person.class}, value={"person"})
public class PersonController {
private final static String PERSON_VIEW_NAME = "person-form";
private ResumeManager resumeManager;
#Autowired()
public PersonController(ResumeManager resume) {
this.resumeManager = resume;
}
#InitBinder
public void initBinder(WebDataBinder dataBinder) {
dataBinder.setDisallowedFields("id");
SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");
dateFormat.setLenient(false);
dataBinder.registerCustomEditor(Date.class, new CustomDateEditor(dateFormat, true));
}
#RequestMapping(value="/person/edit/save")
public String save(#ModelAttribute(value="person") Person p, BindingResult result, SessionStatus status) {
new PersonValidator().validate(p, result);
Collections.sort(p.getEmails()); //this collection still contains client-side dropped objects
this.resumeManager.savePerson(p);
return PERSON_VIEW_NAME;
}
}

Explanation
When you load a page with <form:form modelAttribute="person" ...>, there are two cases :
case 1 : if person doesn't exist, it creates an empty Person
case 2 : if person already exists, it uses it
In all cases, when a page is loaded, there is an existing person.
When you submit a form, Spring MVC updates this existing person only with the submitted information.
So in case 1, if you submit email 1, 2, 3 and 4, Spring MVC will add 4 emails to the empty person. No problem for you in this case.
But in case 2 (for example when you edit an existing person in session), if you submit email 1 and 2, but person has already 4 emails, then Spring MVC will just replace email 1 and 2. Email 3 and 4 still exist.
A possible solution
Probably not the best one, but it should work.
Add a remove boolean to the Email class :
...
public class Email {
...
private boolean remove; // Set this flag to true to indicate that
// you want to remove the person.
...
}
In the save method of your controller, remove the emails that have remove set to true.
Finally, in your JSP, add this hidden field :
<form:hidden path="emails[${status.index}].remove" />
And tell your Javascript to set the input value to true when the user clicks to delete the email.

Alternate solution to Jerome Dalbert one
Jerome's solution should work (thanks again for clear answer and solution), but I didn't want to modify business model.
So here is the way I found out: mark HTML elements to remove using java-script and actually remove it using ajax calls at form submit (I initially avoided ajax to keep model unchanged until user submits, but this solutions preserves that requirement).
JSP:
<%# taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%# taglib prefix="form" uri="http://www.springframework.org/tags/form" %>
<%# taglib prefix="fn" uri="http://java.sun.com/jsp/jstl/functions" %>
<%# taglib prefix="fmt" uri="http://java.sun.com/jsp/jstl/fmt" %>
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"></meta>
<link rel="stylesheet" href="<c:url value="/styles/resume.css"/>" type="text/css"></link>
<link href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8/themes/base/jquery-ui.css" rel="stylesheet" type="text/css"></link>
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.8/jquery.min.js"></script>
<script src="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8/jquery-ui.min.js"></script>
<script src="/resume/js/jquery.editable-1.0.1.js"></script>
<title>Resumes manager</title>
<script>
$('.sortable').sortable({
update: function(event,ui) {
var liElements = this.getElementsByTagName('li');
$(liElements).each(function(i, liElement) {
var orderElements = liElement.getElementsByClassName('order');
$(orderElements).each(function (j, orderElement) {
orderElement.value = i;
});
});
}
});
$('.trashable').click(function() {
$(this.parentNode.childNodes).each(function(index, element) {
if(element.src.match(/trash.png/) != null) {
element.src = '/resume/images/back.png';
this.parentNode.className = 'trashed';
} else if(element.src.match(/back.png/) != null) {
element.src = '/resume/images/trash.png';
this.parentNode.className = '';
} else {
element.disabled = !element.disabled;
}
});
});
function trash(element) {
var sfx = element.alt;
var lnk = ('/resume/person/edit/').concat(sfx);
$.ajax({
url: lnk
});
}
$('#personForm').submit(function() {
var trashed = $(this).find('.trashed');
$(trashed).each(function(index, element) {
var img = $(element).find('.trashable');
var tmp = $(img)[0];
trash(tmp);
});
});
});
</script>
</head>
<body>
<h1>Personal data</h1>
<form:form modelAttribute="person" action="/resume/person/edit/save" id="personForm" method="post" >
<table>
<tr>
<td>Email addresses:</td>
<td colspan="4">
<ol class="sortable">
<c:forEach items="${person.emails}" varStatus="status">
<li><form:hidden path="emails[${status.index}].order" class="order"></form:hidden><form:input path="emails[${status.index}].label"></form:input><form:input type="email" path="emails[${status.index}].value"></form:input><img src="/resume/images/trash.png" class="trashable" alt="dropEmail/${person.emails[status.index].id}"></img></li>
</c:forEach>
</ol>
</td>
</tr>
<tr><td colspan="5"><form:button name="save" value="${person.id}">${person.id == 0 ? 'save' : 'update'}</form:button></td></tr>
</table>
</form:form>
</body>
</html>
Controller:
#Controller
#SessionAttributes(types={Person.class}, value={"person"})
public class PersonController {
private final static String PERSON_VIEW_NAME = "person-form";
private ResumeManager resumeManager;
#Autowired()
public PersonController(ResumeManager resume) {
this.resumeManager = resume;
}
#InitBinder
public void initBinder(WebDataBinder dataBinder) {
dataBinder.setDisallowedFields("id");
SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");
dateFormat.setLenient(false);
dataBinder.registerCustomEditor(Date.class, new CustomDateEditor(dateFormat, true));
}
#RequestMapping(value="/person/edit/{id}")
public String edit(#PathVariable("id") long personId, Model model) {
Person p = this.resumeManager.getPersonById(personId);
if(p != null) {
model.addAttribute("person", p);
return PERSON_VIEW_NAME;
} else {
return "redirect:/";
}
}
#RequestMapping(value="/person/edit/save")
public String save(#ModelAttribute(value="person") Person p, BindingResult result, SessionStatus status) {
new PersonValidator().validate(p, result);
Collections.sort(p.getEmails());
this.resumeManager.savePerson(p);
return PERSON_VIEW_NAME;
}
#RequestMapping(value="/person/edit/dropEmail/{id}")
#ResponseBody
public void dropEmail(#ModelAttribute(value="person") Person p, #PathVariable("id") long id) {
int i = 0;
for(Email e : p.getEmails()) {
if(e.getId() == id) {
p.getEmails().remove(i);
break;
}
i++;
}
}
}