introducing jackson

{data:[
	"firstName":"Gula",
	"lastName":"Nurmatova",
	"height":5.6,
	"children":
	[
		{"name":"Zain"}, 
		{"name":"Hania"}
	]
	"address":{
	"street":"budd circle"
	"state":"CT"
	}
],
"page":"1"
}

add jackson dependencies in pom.xml:
under properties:
    <jackson.version>2.7.1</jackson.version>

under dependencies:
       <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-core</artifactId>
            <version>${jackson.version}</version>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>${jackson.version}</version>
        </dependency>

Run:

$ mvn clean package

then:

$ mvn eclipse:eclipse

• import org.codehaus.jackson.map.ObjectMapper; to do bindings
  
• create one mapper instance to do all your bindings (you can re-use this object)
• You will need to write your object as string

package test;

import java.util.HashMap;

import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Response;

import com.fasterxml.jackson.databind.ObjectMapper;

@Path("sandbox")
public class Sandbox {
	ObjectMapper mapper = new ObjectMapper();

	@GET
	@Produces(MediaType.TEXT_PLAIN)
	@Path("person")
	public Response getIt() {
		try {
			HashMap<String, String> hm = new HashMap<String, String>();
			hm.put("firstName", "Gula");
			hm.put("lastName", "Nurmatova");
			hm.put("location", "CT");
			return Response.status(Response.Status.OK)
					.entity(mapper.writeValueAsString(hm)).build();
		} catch (Exception e) {
			return Response.status(Response.Status.BAD_REQUEST)
					.entity("Could not process your request").build();
		}
	}
}

Access your application at http://localhost:8080/unh/rest/sandbox/person

You should now see JSON returned in your browser that looks like:

{
  "lastName": "Nurmatova",
  "location": "CT",
  "firstName": "Gula"
}

Serializing custom objects

• You need Getters and Setters for the Jackson serializer to work or make your fields public

package test;

import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Response;

import com.fasterxml.jackson.databind.ObjectMapper;

@Path("sandbox")
public class Sandbox {
	ObjectMapper mapper = new ObjectMapper();

	@GET
	@Produces(MediaType.APPLICATION_JSON)
	@Path("person")
	public Response getIt() {
		try {
			Person gula = new Person("Gula", "Nurmatova", "CT");
			String strGula = mapper.writeValueAsString(gula);
			return Response.status(Response.Status.OK)
					.entity(strGula).build();
		} catch (Exception e) {
			e.printStackTrace();
			return Response.status(Response.Status.BAD_REQUEST)
					.entity("Could not process your request").build();
		}
	}
}

class Person {
	public String getLastName() {
		return lastName;
	}

	public void setLastName(String lastName) {
		this.lastName = lastName;
	}

	public String getFirstName() {
		return firstName;
	}

	public void setFirstName(String firstName) {
		this.firstName = firstName;
	}

	public String getLocation() {
		return location;
	}

	public void setLocation(String location) {
		this.location = location;
	}

	String lastName;
	String firstName;
	String location;

	public Person(String firstName, String lastName, String location) {
		this.firstName = firstName;
		this.lastName = lastName;
		this.location = location;
	}
}

The above example serializes the object as String, we can also serialize it as file:

Person gula = new Person("Gula", "Nurmatova", "CT");
File jsonGula = new File("result.json");
mapper.writeValue(jsonGula, gula);
return Response.status(Response.Status.OK).entity(jsonGula).build();


or as Byte array:

Person gula = new Person("Gula", "Nurmatova", "CT");
byte[] jsonBytes = mapper.writeValueAsBytes(gula);
return Response.status(Response.Status.OK).entity(jsonBytes).build();


Nested Objects and JSON Lists

package test;

import java.util.ArrayList;

import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Response;

import com.fasterxml.jackson.databind.ObjectMapper;

@Path("sandbox")
public class Sandbox {
	ObjectMapper mapper = new ObjectMapper();

	@GET
	@Produces(MediaType.APPLICATION_JSON)
	@Path("person")
	public Response getIt() {
		try {
			ArrayList<String> locations = new ArrayList<String> ();
			locations.add("CT");
			locations.add("CA");
			Person gula = new Person("Gula", "Nurmatova", locations);
			String strGula = mapper.writeValueAsString(gula);
			
			return Response.status(Response.Status.OK)
					.entity(strGula).build();
		} catch (Exception e) {
			e.printStackTrace();
			return Response.status(Response.Status.BAD_REQUEST)
					.entity("Could not process your request").build();
		}
	}
}

class Person {
	public String getLastName() {
		return lastName;
	}

	public void setLastName(String lastName) {
		this.lastName = lastName;
	}

	public String getFirstName() {
		return firstName;
	}

	public void setFirstName(String firstName) {
		this.firstName = firstName;
	}

	public ArrayList getLocation() {
		return locations;
	}

	public void setLocation(ArrayList<String>  location) {
		this.locations = location;
	}

	String lastName;
	String firstName;
	ArrayList<String>  locations;

	public Person(String firstName, String lastName, ArrayList<String>  location) {
		this.firstName = firstName;
		this.lastName = lastName;
		this.locations = location;
	}
}

The response now is:

{
  "lastName": "Nurmatova",
  "firstName": "Gula",
  "location": [
    "CT",
    "CA"
  ]
}