best approach for marshaling unmarshaling immutable objects with builder pattern

Question

I have a simple restful service that I'm developing in java. I have been looking at a few of the options for marshalling/unmarshalling json. The possible approaches available, jaxb jackson etc, are quite new to me and I'm trying to find my feet with them. I was wondering if I could get some advice on what would be the best approach and technology to use especially given that many of the objects I'm interested in I have implemented as being immutable and I have used the builder pattern. So there are no setters and the constructor is private.

I have looked at this previous question: Jackson + Builder Pattern? posted on stackoverflow. I am considering something like this approach although it would be great to get some pointers to more resources about using @JsonDeserialize

Here is a very simple example of the type of object I'm considering

public class Reading {

private final double xCoord;
private final double yCoord;
private final double diameter;
private final double reliability;
private final String qualityCode;


private Reading(Builder builder){
    xCoord = builder.xCoord;
    yCoord = builder.yCoord;
    diameter = builder.diameter;
    reliability = builder.reliability;
    qualityCode = builder.qualityCode;
}


public static class Builder {
    //required parameters
    private final double diameter;
    //optional parameters
    private double xCoord = 0.0;
    private double yCoord = 0.0;
    private double reliability = 1.0;
    private String qualityCode;


    public Builder (double diameter){
        this.diameter = diameter;
    }

    public Builder reliability(double val){
        reliability = val;
        return this;
    }

    public Builder qualityCode(String qualityCode){
        this.qualityCode = qualityCode;
        return this;
    }

    public Builder coordinates(double xCoord, double yCoord){
        this.xCoord = xCoord;
        this.yCoord = yCoord;
        return this;
    }

    public Reading build(){
        return new Reading(this);
    }

}

public double getXCoord() {return xCoord;}

public double getYCoord() {return yCoord;}

public String getQualityCode() {return qualityCode;}

public double getDiameter() { return diameter;}

public double getReliability() {return reliability; }

}

There are no problems marshalling this object but unmarshalling doesn't seem to be straight forward. Also is there support for leaving out entries for object values that are null?

Answer 1

you can do this: (implement only getters and use XmlAccessType.FIELD)

@XmlAccessorType(XmlAccessType.FIELD)
public class CreditCardVO implements Serializable {

  private Long ccNumber;
  private String ccName;


  public CreditCardVO(Long ccNumber, String ccName) {
   this.ccNumber = ccNumber;
   this.ccName = ccName;
  }


  private CreditCardVO() {
     // for JAXB's Magic
  }

  public Long getCcNumber() {
    return ccNumber;
  }

  public String getCcName() {
   return ccName;
  }    
}

taken from http://aniketshaligram.blogspot.com/2010/05/jaxb-immutable-objects.html