PersistableHashBuilder.java

/*
 * (c) Copyright 2005-2012 JAXIO, www.jaxio.com
 * Source code generated by Celerio, a Jaxio product
 * Want to use Celerio within your company? email us at info@jaxio.com
 * Follow us on twitter: @springfuse
 * Template pack-backend-sd:src/main/java/project/domain/PersistableHashBuilder.p.vm.java
 */
package com.company.demo.domain;

import java.io.Serializable;

import org.apache.log4j.Logger;
import org.springframework.data.domain.Persistable;

/**
 * The first time the {@link #hash(Persistable)} is called, we check if the primary key is present or not.
 * <ul>
 * <li>If yes: we use it to get the hash
 * <li>If no: we use a VMID during the entire life of this instance even if later on this instance is assigned a primary key.
 * </ul>
 */
public class PersistableHashBuilder implements Serializable {
    private static final Logger log = Logger.getLogger(PersistableHashBuilder.class);
    private static final long serialVersionUID = 1L;
    private Object technicalId;

    public int hash(Persistable<?> persistable) {
        if (technicalId == null) {
            if (!persistable.isNew()) {
                technicalId = persistable.getId();
            } else {
                technicalId = new java.rmi.dgc.VMID();
                log.warn("DEVELOPER: hashCode has changed!." //
                        + "If you encounter this message you should take the time to carefuly " //
                        + "review the equals/hashCode methods for: " + persistable.getClass().getCanonicalName());
            }
        }
        return technicalId.hashCode();
    }
}