The document discusses using Jackson annotations in Mule ESB to map JSON fields to object properties when converting between JSON and Java objects. It demonstrates annotating the Java object's properties with @JsonProperty to specify the name of the corresponding JSON field, since they do not match by default. This allows automatic mapping of the sample input JSON to the Java object class provided, resolving an error caused by unrecognized JSON field names.

1. Mule ESB
How to use Jackson in Json to Object converter
Gennaro Spagnoli - 2016

2. In this tutorial we will be creating an easy json to object converter using Jackson annotations
in order to have major control on the fields datamapping.
As usual, let’s begin creating the http inbound component to get the input JSON
Suppose now we will have this json in input:
{ "name" : "Gennaro", "surname" : "Spagnoli", "profession" : "programmer"}

3. We want to transform this json to this java object:
package com.mulechampion;
import java.io.Serializable;
public class JsonClass implements Serializable{
/**
*
*/
private static final long serialVersionUID = -5645625751838751914L;
private String fullName;
private String fullSurname;
private String job;
public String getFullName() {
return fullName;
}
public void setFullName(String fullName) {
this.fullName = fullName;
}
public String getFullSurname() {
return fullSurname;
}
public void setFullSurname(String fullSurname) {
this.fullSurname = fullSurname;
}
public String getJob() {
return job;
}
public void setJob(String job) {
this.job = job;
}
@Override
public String toString() {
return "JsonClass [fullName=" + fullName + ", fullSurname="
+ fullSurname + ", job=" + job + "]";
}
}

4. The problem here is that there’s no automatic field mapping based on the fields name,
resulting in the following error, if we start the application with this flow:
org.codehaus.jackson.map.exc.UnrecognizedPropertyException: Unrecognized field "name"
(Class com.mulechampion.JsonClass), not marked as ignorable
To solve this, we will use Jackson annotations in this way:
@JsonProperty(value="name")
private String fullName;
@JsonProperty(value="surname")
private String fullSurname;
@JsonProperty(value="profession")
private String job;

5. If we start now the application we will finally obtain the following output on the console:
HTTP_Listener_Configuration.worker.01]
org.mule.api.processor.LoggerMessageProcessor: JsonClass [fullName=Gennaro,
fullSurname=Spagnoli, job=programmer]