Java tutorial
/* 50AH-code ========= 50 Android Hacks (http://manning.com/sessa/) book source code Copyright (c) 2012 Manning Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */ /******************************************************************************* * Copyright (c) 2012 Manning * See the file license.txt for copying permission. ******************************************************************************/ package com.manning.androidhacks.hack041.data; import android.content.Context; import android.database.sqlite.SQLiteDatabase; import android.util.Log; import com.j256.ormlite.android.apptools.OrmLiteSqliteOpenHelper; import com.j256.ormlite.dao.Dao; import com.j256.ormlite.misc.TransactionManager; import com.j256.ormlite.support.ConnectionSource; import com.j256.ormlite.table.TableUtils; import java.sql.SQLException; import java.util.concurrent.Callable; /** * A SqliteOpenHelper that we will use as a singleton in our application. */ public class DatabaseHelper extends OrmLiteSqliteOpenHelper { public static final String TAG = "DatabaseHelper"; public static final String DATABASE_NAME = "demo.db"; private static final int DATABASE_VERSION = 1; private static DatabaseHelper instance; /** * @param c * A context to use when initializing the database for the first * time. * @return A single instance of DatabaseHelper. */ public static synchronized DatabaseHelper getInstance(Context c) { if (instance == null) instance = new DatabaseHelper(c); return instance; } private DatabaseHelper(Context context) { super(context, DATABASE_NAME, null, DATABASE_VERSION); } @Override public void onCreate(SQLiteDatabase sqLiteDatabase, ConnectionSource connectionSource) { // Here, TableUtils will use the Annotations on our classes to create all of // the tables in our relation. try { /* * When using foreign keys, we must be sure to create tables in the proper * order. For example, since the ArticleCategory table has foreign keys to * both the Article and Category tables, we must declare ArticleCategory * after the two others. */ TableUtils.createTable(connectionSource, Category.class); TableUtils.createTable(connectionSource, Article.class); TableUtils.createTable(connectionSource, ArticleCategory.class); TableUtils.createTable(connectionSource, Author.class); TableUtils.createTable(connectionSource, ArticleAuthor.class); TableUtils.createTable(connectionSource, Comment.class); } catch (SQLException e) { Log.e(TAG, "Unable to create tables.", e); throw new RuntimeException(e); } } @Override public void onUpgrade(SQLiteDatabase sqLiteDatabase, ConnectionSource connectionSource, int oldVersion, int newVersion) { try { // When using foreign keys, we must be sure to drop tables in the proper // order, again. TableUtils.dropTable(connectionSource, Comment.class, false); TableUtils.dropTable(connectionSource, ArticleAuthor.class, false); TableUtils.dropTable(connectionSource, ArticleCategory.class, false); TableUtils.dropTable(connectionSource, Category.class, false); TableUtils.dropTable(connectionSource, Author.class, false); TableUtils.dropTable(connectionSource, Article.class, false); onCreate(sqLiteDatabase, connectionSource); } catch (SQLException e) { Log.e(TAG, "Unable to drop tables.", e); throw new RuntimeException(e); } } @Override public void onOpen(SQLiteDatabase db) { super.onOpen(db); db.execSQL("PRAGMA foreign_keys=ON;"); } /** * Creates a TransactionManager, and runs the given callback. * * @param callback * A Callable to run from inside a transaction. * @param <T> * The return type of the Callable. * @return The result of the Callable that was passed in. */ public <T> T callInTransaction(Callable<T> callback) { try { return new TransactionManager(getConnectionSource()).callInTransaction(callback); } catch (SQLException e) { Log.e(TAG, "Exception occurred in transaction.", e); throw new RuntimeException(e); } } /* DAO object accessors with specific types. */ public Dao<Article, Integer> getArticleDao() throws SQLException { return getDao(Article.class); } public Dao<Category, Integer> getCategoryDao() throws SQLException { return getDao(Category.class); } public Dao<Comment, Integer> getCommentDao() throws SQLException { return getDao(Comment.class); } public Dao<Author, Integer> getAuthorDao() throws SQLException { return getDao(Author.class); } public Dao<ArticleAuthor, Void> getArticleAuthorDao() throws SQLException { return getDao(ArticleAuthor.class); } public Dao<ArticleCategory, Void> getArticleCategoryDao() throws SQLException { return getDao(ArticleCategory.class); } }