Returning returned model object to json String using spring data jpa with hibernate - spring

Question

I am using spring data jpa with hibernate
This is my dao interface
#Repository
public interface IUserDAO extends JpaRepository<User, Integer>{
User findByUsername( final String username );
}
This is my User class
Entity
#Table(name="USER")
public class User {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(name="ID", nullable = false)
private int id;
#Column(name="USERNAME", nullable = false)
private String username;
#Column(name="NAME", nullable = false)
private String name;
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 getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
This is my UserImplClass
This is my UserImplClass{
#Autowired
private IUserDAO iUserDAO;
public String findUserByUserName(String username) {
User user =iUserDAO.findByUsername(username);
Convert user to json object from framework level automatically
// i can add my one implemenation of converting user to json here ,but i want to achieve it from framework so that my code is not scattered on every service level
return "jsonStringOfUserObject"
}
Is it possible with spring data jpa with hibernate so that i do not have to write code for converting java object to json string in every service level?
I am using spring ,therefore i want to achieve it from spring .

Answer 1

You have two options to do what you want:
1) If you plan on returning this Object as an HTTP Response, and you use Spring MVC with Controllers you can annotate your controller method as follows:
public #ResponseBody User getUser(){
return userImplClass.findUserByUserName("yourusername");
}
2) If you want the UserImplClass itself to return a JSON String (which I do't recommend, but I leave you the decision), you can use Jackson Object Mapper to do it for you (you can inject it if you declare it as a bean on your configuration xml, or create a new instance of it, I personally prefer injecting it with #Autowired)
public String findUserByUserName(String username) {
User user =iUserDAO.findByUsername(username);
ObjectMapper mapper = new ObjectMapper(); // no need to do this if you inject via #Autowired
return mapper.writeValueAsString(user);
}