DatabaseConsumerService.java

/*
    This file is part of RateBeer For Android.
    
    RateBeer for Android is free software: you can redistribute it 
    and/or modify it under the terms of the GNU General Public 
    License as published by the Free Software Foundation, either 
    version 3 of the License, or (at your option) any later version.

    RateBeer for Android is distributed in the hope that it will be 
    useful, but WITHOUT ANY WARRANTY; without even the implied warranty 
    of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with RateBeer for Android.  If not, see 
    <http://www.gnu.org/licenses/>.
 */
package com.ratebeer.android.gui.components.helpers;

import android.app.IntentService;
import android.content.Context;

import com.j256.ormlite.android.apptools.OpenHelperManager;
import com.j256.ormlite.android.apptools.OrmLiteSqliteOpenHelper;
import com.j256.ormlite.support.ConnectionSource;
import com.ratebeer.android.app.persistance.DatabaseHelper;

public abstract class DatabaseConsumerService extends IntentService {

	public DatabaseConsumerService(String name) {
		super(name);
	}

	private volatile DatabaseHelper helper;
	private volatile boolean created = false;
	private volatile boolean destroyed = false;

	/**
	 * Get a helper for this action.
	 */
	public DatabaseHelper getHelper() {
		if (helper == null) {
			if (!created) {
				throw new IllegalStateException("A call has not been made to onCreate() yet so the helper is null");
		} else if (destroyed) {
				throw new IllegalStateException(
						"A call to onDestroy has already been made and the helper cannot be used after that point");
			} else {
				throw new IllegalStateException("Helper is null for some unknown reason");
			}
		} else {
			return helper;
		}
	}

	/**
	 * Get a connection source for this action.
	 */
	public ConnectionSource getConnectionSource() {
		return getHelper().getConnectionSource();
	}

	@Override
	public void onCreate() {
		if (helper == null) {
			helper = getHelperInternal(this);
			created = true;
		}
		super.onCreate();
	}

	@Override
	public void onDestroy() {
		super.onDestroy();
		releaseHelper(helper);
		destroyed = true;
	}

	/**
	 * This is called internally by the class to populate the helper object instance. This should not be called directly
	 * by client code unless you know what you are doing. Use {@link #getHelper()} to get a helper instance. If you are
	 * managing your own helper creation, override this method to supply this activity with a helper instance.
	 * 
	 * <p>
	 * <b> NOTE: </b> If you override this method, you most likely will need to override the
	 * {@link #releaseHelper(OrmLiteSqliteOpenHelper)} method as well.
	 * </p>
	 */
	protected DatabaseHelper getHelperInternal(Context context) {
		DatabaseHelper newHelper = (DatabaseHelper) OpenHelperManager.getHelper(context, DatabaseHelper.class);
		return newHelper;
	}

	/**
	 * Release the helper instance created in {@link #getHelperInternal(Context)}. You most likely will not need to call
	 * this directly since {@link #onDestroy()} does it for you.
	 * 
	 * <p>
	 * <b> NOTE: </b> If you override this method, you most likely will need to override the
	 * {@link #getHelperInternal(Context)} method as well.
	 * </p>
	 */
	protected void releaseHelper(DatabaseHelper helper) {
		OpenHelperManager.releaseHelper();
		helper = null;
	}
	
}