javajsonserializationjacksonfasterxml

How to implement customized serialization feature in fasterxml


My JSON:

{ "name": "asdf", "age": "15", "address": { "street": "asdf" } }

If street is null, with JsonSerialize.Inclusion.NON_NULL, I can get..

{ "name": "asdf", "age": "15", "address": {} }

But I want to get something like this.. (when address is not null, it is a new/empty object. But street is null.)

{ "name": "asdf", "age": "15" }

I thought to have custom serialization feature like JsonSerialize.Inclusion.VALID_OBJECT. Adding isValid() method in the Address class then if that returns true serialize else don't serialize.

But I don't know how to proceed further/which class to override. Is this possible or any other views on this? Please suggest.


Added classes

public static void main(String[] args) {
    ObjectMapper mapper = new ObjectMapper();
    Customer customer = new Customer();
    customer.setName("name");
    customer.setAddress(new Address());
    mapper.writeValue(new File("d:\\customer.json"), customer);
}

@JsonSerialize(include = JsonSerialize.Inclusion.NON_NULL)
public class Customer {

private String name;
private Address address;

public String getName() {
    return name;
}
public void setName(String name) {
    this.name = name;
}
public Address getAddress() {
    return address;
}
public void setAddress(Address address) {
    this.address = address;
}
}

@JsonSerialize(include = JsonSerialize.Inclusion.NON_NULL)
public class Address {

private String street;

public String getStreet() {
    return street;
}
public void setStreet(String street) {
    this.street = street;
}
}

Note: I am not worrying about deserialization now. i.e, loss of address object.

Thanks in advance.


Solution

  • Customized JSON Object using Serialization:

    An example:

    Loan Application (POJO Class)

    import java.io.Serializable;
    import org.webservice.business.serializer.LoanApplicationSerializer;
    import com.fasterxml.jackson.databind.annotation.JsonSerialize;
    
    @JsonSerialize(using=LoanApplicationSerializer.class)
    public class LoanApplication implements Serializable {
    
        private static final long serialVersionUID = 1L;
        private double amount;
        private String businessType;
    }
    
    package org.ovamba.business.serializer;
    
    import java.io.IOException;
    import org.webservice.business.dto.LoanApplication;
    import com.fasterxml.jackson.core.JsonGenerator;
    import com.fasterxml.jackson.core.JsonProcessingException;
    import com.fasterxml.jackson.databind.JsonSerializer;
    import com.fasterxml.jackson.databind.SerializerProvider;
    
    public class LoanApplicationSerializer extends JsonSerializer<LoanApplication> {
    
        @Override
        public void serialize(LoanApplication prm_objObjectToSerialize, JsonGenerator prm_objJsonGenerator, SerializerProvider prm_objSerializerProvider) throws IOException, JsonProcessingException {
            if (null == prm_objObjectToSerialize) {
            } else {
                try {
                    prm_objJsonGenerator.writeStartObject();
                    prm_objJsonGenerator.writeNumberField("amount", prm_objObjectToSerialize.getAmount());
                    prm_objJsonGenerator.writeStringField("businesstype", prm_objObjectToSerialize.getBusinessType());
                } catch (Exception v_exException) {
                    //ExceptionController.getInstance().error("Error while Serializing the Loan Application Object", v_exException);
                } finally {
                    prm_objJsonGenerator.writeEndObject();
                }
            }
          }
        }