AbstractSavable.java

// Copyright (c) 2003  Dustin Sallings <dustin@spy.net>

package net.spy.db;

import java.util.Collection;

import net.spy.SpyObject;

/**
 * Abstract implementation of {@link Savable}.
 */
public abstract class AbstractSavable extends SpyObject
	implements Savable, TransactionListener {

	private boolean asIsNew=false;
	private boolean asIsModified=false;

	private final Exception createdHere;

	/**
	 * Get an instance of AbstractSavable.
	 *
	 * An object instantiated with this constructor will have the new flag
	 * set.  If this is not desirable, unset it.
	 */
	protected AbstractSavable() {
		super();
		createdHere=new UnsavedObjectWarning();
		createdHere.fillInStackTrace();
		asIsNew=true;
	}

	/**
	 * Indicate whether this object is new.
	 */
	public boolean isNew() {
		return(asIsNew);
	}

	/**
	 * Indicate whether this object has been modified.
	 */
	public boolean isModified() {
		return(asIsModified);
	}

	/**
	 * Set the ``new'' flag for this object.
	 *
	 * @param to the new value of the new flag
	 */
	protected void setNew(boolean to) {
		asIsNew=to;
	}

	/**
	 * Set the ``modified'' flag for this object.
	 *
	 * @param to the new value for the modified flag
	 */
	protected void setModified(boolean to) {
		asIsModified=to;
	}

	/**
	 * Mark this AbstractSavable as modified.
	 */
	public void modify() {
		setModified(true);
	}

	/**
	 * Get the objects that need to be saved before this object.
	 * The default implementation returns null, indicating that there are
	 * no prerequisite objects.
	 */
	public Collection<? extends Savable> getPreSavables(SaveContext context) {
		return(null);
	}

	/**
	 * Get the dependent objects for this Savable. The default
	 * implementation returns null, indicating that there are no dependent
	 * objects.
	 */
	public Collection<? extends Savable> getPostSavables(SaveContext context) {
		return(null);
	}

	/**
	 * Whenever this transaction is committed, automatically flag it as saved.
	 */
	public void transactionCommited() {
		setNew(false);
		setModified(false);
	}

	/**
	 * If this object is still <q>dirty</q> during finalization, log it.
	 */
	@Override
	protected void finalize() throws Throwable {
		if(isNew() || isModified()) {
			getLogger().debug("Finalizing and object that needs saving",
				createdHere);
		}
	}

	private static final class UnsavedObjectWarning extends Exception {
		public UnsavedObjectWarning() {
			super("CREATED HERE");
		}
	}
}