Spring MVC to REST - spring

Question

I have a Spring MVC aplication. I want to convert it to a RESTful
webservice, which returns a JSON response. Can somebody help me with this??
Basically, I want to convert my controller to a REST controller.
My Code :
///////////////////////////PersonController//////////////////////////////
package com.journaldev.spring;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import com.journaldev.spring.model.Person;
import com.journaldev.spring.service.PersonService;
#Controller
public class PersonController {
private PersonService personService;
#Autowired(required=true)
#Qualifier(value="personService")
public void setPersonService(PersonService ps){
this.personService = ps;
}
#RequestMapping(value = "/persons", method = RequestMethod.GET)
public String listPersons(Model model) {
model.addAttribute("person", new Person());
model.addAttribute("listPersons", this.personService.listPersons());
return "person";
}
//For add and update person both
#RequestMapping(value= "/person/add", method = RequestMethod.POST)
public String addPerson(#ModelAttribute("person") Person p){
if(p.getId() == 0){
//new person, add it
this.personService.addPerson(p);
}else{
//existing person, call update
this.personService.updatePerson(p);
}
return "redirect:/persons";
}
#RequestMapping("/remove/{id}")
public String removePerson(#PathVariable("id") int id){
this.personService.removePerson(id);
return "redirect:/persons";
}
#RequestMapping("/edit/{id}")
public String editPerson(#PathVariable("id") int id, Model model){
model.addAttribute("person", this.personService.getPersonById(id));
model.addAttribute("listPersons", this.personService.listPersons());
return "person";
}
}
/////////////////////////////////PersonDAO/////////////////////////////
package com.journaldev.spring.dao;
import java.util.List;
import com.journaldev.spring.model.Person;
public interface PersonDAO {
public void addPerson(Person p);
public void updatePerson(Person p);
public List<Person> listPersons();
public Person getPersonById(int id);
public void removePerson(int id);
}
///////////////////////////////PersonDAOImpl/////////////////////////
package com.journaldev.spring.dao;
import java.util.List;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Repository;
import com.journaldev.spring.model.Person;
#Repository
public class PersonDAOImpl implements PersonDAO {
private static final Logger logger = LoggerFactory.getLogger(PersonDAOImpl.class);
private SessionFactory sessionFactory;
public void setSessionFactory(SessionFactory sf){
this.sessionFactory = sf;
}
#Override
public void addPerson(Person p) {
Session session = this.sessionFactory.getCurrentSession();
session.persist(p);
logger.info("Person saved successfully, Person Details="+p);
}
#Override
public void updatePerson(Person p) {
Session session = this.sessionFactory.getCurrentSession();
session.update(p);
logger.info("Person updated successfully, Person Details="+p);
}
#SuppressWarnings("unchecked")
#Override
public List<Person> listPersons() {
Session session = this.sessionFactory.getCurrentSession();
List<Person> personsList = session.createQuery("from Person").list();
for(Person p : personsList){
logger.info("Person List::"+p);
}
return personsList;
}
#Override
public Person getPersonById(int id) {
Session session = this.sessionFactory.getCurrentSession();
Person p = (Person) session.load(Person.class, new Integer(id));
logger.info("Person loaded successfully, Person details="+p);
return p;
}
#Override
public void removePerson(int id) {
Session session = this.sessionFactory.getCurrentSession();
Person p = (Person) session.load(Person.class, new Integer(id));
if(null != p){
session.delete(p);
}
logger.info("Person deleted successfully, person details="+p);
}
}
//////////////////////////////////Person(Model)///////////////////////
package com.journaldev.spring.model;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;
/**
* Entity bean with JPA annotations
* Hibernate provides JPA implementation
* #author pankaj
*
*/
#Entity
#Table(name="PERSON")
public class Person {
#Id
#Column(name="id")
#GeneratedValue(strategy=GenerationType.IDENTITY)
private int id;
private String name;
private String country;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getCountry() {
return country;
}
public void setCountry(String country) {
this.country = country;
}
#Override
public String toString(){
return "id="+id+", name="+name+", country="+country;
}
}
///////////////////////////////////PersonService///////////////////
package com.journaldev.spring.service;
import java.util.List;
import com.journaldev.spring.model.Person;
public interface PersonService {
public void addPerson(Person p);
public void updatePerson(Person p);
public List<Person> listPersons();
public Person getPersonById(int id);
public void removePerson(int id);
}
//////////////////////////////ServiceImpl////////////////////////////
package com.journaldev.spring.service;
import java.util.List;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import com.journaldev.spring.dao.PersonDAO;
import com.journaldev.spring.model.Person;
#Service
public class PersonServiceImpl implements PersonService {
private PersonDAO personDAO;
public void setPersonDAO(PersonDAO personDAO) {
this.personDAO = personDAO;
}
#Override
#Transactional
public void addPerson(Person p) {
this.personDAO.addPerson(p);
}
#Override
#Transactional
public void updatePerson(Person p) {
this.personDAO.updatePerson(p);
}
#Override
#Transactional
public List<Person> listPersons() {
return this.personDAO.listPersons();
}
#Override
#Transactional
public Person getPersonById(int id) {
return this.personDAO.getPersonById(id);
}
#Override
#Transactional
public void removePerson(int id) {
this.personDAO.removePerson(id);
}
}

Answer 1

First you have to add Jackson Databind dependency in your pom file then you can define your rest controller for exemple :
#RestController
public class PersonRestService {
#Autowired
private PersonService personService ;
#RequestMapping(value="/persons",method=RequestMethod.POST)
public Person addPerson(#RequestBody Person Person) {
return personService.addPerson(Person);
}
#RequestMapping(value="/persons",method=RequestMethod.Delete)
public void deletePerson(int code) {
personService.deletePerson(code);
}
#RequestMapping(value="/persons",method=RequestMethod.GET)
public Person getPerson(#RequestParam int code) {
return personService.getPersonById(code);
}
#RequestMapping(value="/allPersons",method=RequestMethod.GET)
public List<Person> getAllPerson() {
return personService.getAllPerson();
}
}

Answer 2

Its easy, what you need to do is add a response in JSON for all request which need it.
The annotation is #ResponseBody and you can return any object, jackson will serialize it to json format for you.
For example in your code:
#RequestMapping("/remove/{id}")
#ResponseBody
public boolean removePerson(#PathVariable("id") int id){
this.personService.removePerson(id);
//true if everything was OK, false if some exception
return true;
}
...
#RequestMapping(value = "/persons", method = RequestMethod.GET)
#ResponseBody
public List<Person> listPersons(Model model) {
return this.personService.listPersons();
}
You only need to modify your controller, to make it RESTFul
Also you will have to add logic to your JS code to handle the new responses values.

Answer 3

Simply use the annotation #RestController.
You can also refer to previously asked question on this link
Difference between spring #Controller and #RestController annotation