com.softberries.klerk.dao.GenericDao.java Source code

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Here is the source code for com.softberries.klerk.dao.GenericDao.java

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/*******************************************************************************
 * Copyright (c) 2011 Softberries Krzysztof Grajek.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 * 
 * Contributors:
 *     Softberries Krzysztof Grajek - initial API and implementation
 ******************************************************************************/
package com.softberries.klerk.dao;

import java.io.File;
import java.net.URL;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.List;

import org.apache.commons.dbutils.QueryRunner;

/**
 * Common functionality for data access objects
 * within Klerk application
 * 
 * @author kris
 *
 */
public abstract class GenericDao<T> {

    /**
     * Pass specific {@link filePath} to the dao
     * @param filePath
     */
    public GenericDao(String filePath) {
        this.filePath = filePath;
    }

    /**
     * Pass specific {@link filePath} to the dao using
     * a File object
     * @param dbFile
     */
    public GenericDao(File dbFile) {
        this.filePath = dbFile.getAbsolutePath();
    }

    /**
     * Database connection object
     */
    protected Connection conn = null;
    /**
     * Keeps the current prepared statement reference
     */
    protected PreparedStatement st = null;
    /**
     * Keeps the current {@code ResultSet} reference
     */
    protected ResultSet generatedKeys = null;
    /**
     * Utility object from Apache library 
     * allowing convertion between {@code ResultSet}
     * and specific Transfer Object
     */
    protected QueryRunner run = null;

    /**
     * Database file location when using file based datastore
     */
    protected String filePath = null;

    /**
     * Initializes connection to the database
     * 
     * @throws ClassNotFoundException
     * @throws SQLException
     */
    public void init() throws ClassNotFoundException, SQLException {
        run = new QueryRunner();
        Class.forName("org.h2.Driver");
        conn = DriverManager.getConnection("jdbc:h2:" + this.filePath, "sa", "");
        conn.setAutoCommit(false);
    }

    /**
     * Closes all resources after execution
     * 
     * @param con {@code Connection} object
     * @param stm {@code PreparedStatement} object
     * @param gk {@code ResultSet} object
     * @throws SQLException
     */
    protected void close(Connection con, PreparedStatement stm, ResultSet gk) throws SQLException {
        if (gk != null) {
            gk.close();
        }
        if (stm != null) {
            stm.close();
        }
        if (con != null) {
            con.close();
        }
    }

    /**
     * Finds all records and convert it to the specific type
     * 
     * @return {@code List<T>} list of specific objects created from {@code ResultSet}
     *  
     * @throws SQLException
     */
    public abstract List<T> findAll() throws SQLException;

    /**
     * Finds object of type <T> in the database
     * 
     * @param id
     * @return
     * @throws SQLException
     */
    public abstract T find(Long id) throws SQLException;

    /**
     * Adds new record to the database based on the Object of type T
     * @param t
     * @throws SQLException
     */
    public abstract void create(T t) throws SQLException;

    /**
     * Updates single record in the database
     * @param t
     * @throws SQLException
     */
    public abstract void update(T t) throws SQLException;

    /**
     * Deletes single record in the database
     * @param id
     * @throws SQLException
     */
    public abstract void delete(Long id) throws SQLException;

    /**
     * Deletes all records in a table corresponding the type T
     * @throws SQLException
     */
    public abstract void deleteAll() throws SQLException;
}