Spring rest not returning my object json - json

Question

Here is my controller:
#Controller
#RequestMapping("api")
public class RestController {
#RequestMapping(value="check",method=RequestMethod.GET,produces="application/json")
#ResponseBody
public UserAcc returnuser(){
return UserDao.getUserById(1);
}
}
... and this is my UserAcc class:
#XmlRootElement
#Entity
#Table(name = "user_acc")
#NamedQueries({
#NamedQuery(name = "UserAcc.findAll", query = "SELECT u FROM UserAcc u")})
public class UserAcc implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Basic(optional = false)
#Column(name = "user_id")
private Integer userId;
#Basic(optional = false)
#Lob
#Column(name = "user_name")
private String userName;
#Basic(optional = false)
#Lob
#Column(name = "Company")
private String company;
#Basic(optional = false)
#Column(name = "user_email")
private String userEmail;
#Basic(optional = false)
#Column(name = "is_account_activated")
private boolean isAccountActivated;
#OneToMany(cascade = CascadeType.ALL, mappedBy = "assigenedToId")
private List<Issues> issuesList;
#OneToMany(cascade = CascadeType.ALL, mappedBy = "assosiateId")
private List<Projectdetails> projectdetailsList;
#OneToMany(cascade = CascadeType.ALL, mappedBy = "moduleassignedtoid")
private List<DevelAcc> develAccList;
#OneToMany(cascade = CascadeType.ALL, mappedBy = "assignedUserId")
private List<TestAcc> testAccList;
// ... code ommitted
}
But i am not getting any json response from userAcc object. Is there any problem? My spring configuration is working fine. Any help is appreciated!

Answer 1

You need to use a library (such as jackson) to convert UserAcc class to json.
Refer to http://www.journaldev.com/2552/spring-restful-web-service-example-with-json-jackson-and-client-program for an example.
#XmlRootElement
public class UserAcc {
.... fields
}

Answer 2

Assuming you have all the required dependencies (as already mentioned in Jack's answer) on your classpath, you could try it like this:
#Controller
#RequestMapping("/api")
public class RestController {
#RequestMapping(value="/check",method=RequestMethod.GET,produces="application/json")
public #ResponseBody UserAcc returnuser(){
return UserDao.getUserById(1);;
}
}
...or like that:
#Controller
#RequestMapping("/api")
public class RestController {
#RequestMapping(value="/check",method=RequestMethod.GET,produces="application/json")
public #ResponseBody Map<String, Object> returnuser(){
UserAcc acc = UserDao.getUserById(1);
Map<String,Object> map = new HashMap<>();
map.put("id",""+acc.getId());
//... and so on
return map;
}
}

Answer 3

I implemented this recently using Jackson (which is used to convert your POJO responses into JSON). Firstly, I added Jackson dependencies to my project (I'm using Maven):
<!-- Jackson for Java - JSON conversion -->
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-core</artifactId>
<version>${jackson-2-version}</version>
</dependency>
<!-- Jackson for Java - JSON conversion -->
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>${jackson-2-version}</version>
</dependency>
<!-- Jackson for Java - JSON conversion -->
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-annotations</artifactId>
<version>${jackson-2-version}</version>
</dependency>
Spring will then automatically use Jackson to generate the JSON response for any Controller method that returns an "application/json" response (as is the case for you).
If you want to prepend your JSON response with some characters to prevent JSON hijacking, then include this in your Spring config file:
<mvc:annotation-driven>
<!-- Set JSON converter (for converting Java to JSON in REST response -->
<mvc:message-converters>
<bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
<!-- Add prefix to JSON response to prevent JSON hijacking -->
<property name="prefixJson" value="true" />
</bean>
</mvc:message-converters>
</mvc:annotation-driven>
this will prepend all JSON responses with this character string:
{} &&
(which should be stripped out by the calling client prior to processing the response).