Process JSON with Jersey and Jackson - json

Question

I am using jersey in Java. I want to get JSON data sent via a post request. However, I am not sure how to do this, despite my searching. I am able to receive JSON data at a path, yet I can't figure out how to parse it into java variables. I assume that I need to use jackson to do this. However, I don't understand how to pass the received JSON to jackson.
#Path("/register")
public class ResourceRegister
{
#POST
#Consumes(MediaType.APPLICATION_JSON)
public String RegisterUser(//not sure what to take in here to get the json )
{
//code to deal with the json
}

Answer 1

There are several ways of accepting the JSON and using it in back-end.
1. set POJO elements using JAXB APIs and use object of that POJO class to access passed parameters. this will be helpful while JSON size is large.
Example:
your service declaration would be as following
#Path("/register")
public class ResourceRegister
{
#POST
#Consumes(MediaType.APPLICATION_JSON)
public String RegisterUser(RegParams regParams)
{
//code to deal with the json
}
.....
}
and you will write a POJO like following
#XmlRootElement
#XmlAccessorType(XmlAccessType.FIELD)
#JsonIgnoreProperties(ignoreUnknown=true)
#JsonWriteNullProperties(false)
public class RegParams implements Serializable {
#JsonProperty("userId")
private long userId;
#JsonProperty("userName")
private String userName;
..
..
}
retrive JSON as a string and use jersey APIs to work with the same.
in this case you can declare your service as following
#Path("/register")
public class ResourceRegister
{
#POST
#Consumes(MediaType.APPLICATION_FORM_URLENCODED)
public String RegisterUser(#FormParam("jsonObj")String jsonString)
{
//code to deal with the json
}
.....
}
and you can process that string by using jersey APIs like following
ObjectMapper om = new ObjectMapper();
JsonNode mainNode = om.readTree(jsonString);
//access fields
mainNode.get..(as per data passed, string, int etc)
for more referance you can refer this or this

Answer 2

You just need to place #JsonProperty annotation to your class properties and add that class to your Resource method as paramater.
You might need #JsonIgnoreProperties annotation as well if you are not deserializing everything inside the incoming json
See below:
#POST
#Consumes(MediaType.APPLICATION_JSON)
public String registerUser(MyUser myUser)
{
//code to deal with the json
}
public class MyUser{
#JsonProperty
private String name;
#JsonProperty
private String surname;
//getters & setters & constructors if you need
}