com.univocity.articles.databases.Database.java Source code

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Here is the source code for com.univocity.articles.databases.Database.java

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/*******************************************************************************
 * Copyright (c) 2014 uniVocity Software Pty Ltd. All rights reserved.
 * This file is subject to the terms and conditions defined in file
 * 'LICENSE.txt', which is part of this source code package.
 ******************************************************************************/
package com.univocity.articles.databases;

import java.io.*;
import java.util.*;

import javax.sql.*;

import org.springframework.jdbc.core.*;
import org.springframework.jdbc.datasource.*;

import com.univocity.api.entity.jdbc.*;

/**
 * A simple class to initialize a given database with the scripts provided under {@code src/main/resources/database/*database_name*}
 *
 * @author uniVocity Software Pty Ltd - <a href="mailto:dev@univocity.com">dev@univocity.com
 *
 */
public abstract class Database {

    private JdbcTemplate jdbcTemplate;

    /**
     * Just an empty constructor. Initialization happens when {@link #initialize(String, String, String, String)} is invoked.
     */
    public Database() {
    }

    /**
     * Initializes this Database object by creating a {@link DataSource} to provide connections to your database.
     * Tables will be created automatically if required.
     *
     * @param tablesToCreate a sequence of table names to create in this database, if they have not been created yet
     * @param connectionUrl the JDBC URL to use for accessing the {@link java.sql.DriverManager}
     * @param username the username to connect to the database
     * @param password the password of the given username, if required
     */
    void initialize(String tablesToCreate, String connectionUrl, String username, String password) {
        try {
            Class.forName(getDriverClassName());
            DataSource dataSource = new SingleConnectionDataSource(connectionUrl, username, password, true);
            this.jdbcTemplate = new JdbcTemplate(dataSource);

        } catch (Exception ex) {
            throw new IllegalStateException(
                    "Error creating database using scripts for database " + getDatabaseName(), ex);
        }

        initializeDatabase(tablesToCreate);
    }

    /**
     * Returns the database name
     * @return the database name
     */
    public abstract String getDatabaseName();

    /**
     * Returns the driver class name which will be loaded using the old-fashioned {@link Class#forName(String)} method before
     * creating a datasource.
     * @return the driver class name.
     */
    abstract String getDriverClassName();

    /**
     * Iterates over all scripts under {@code src/main/resources/database/*database_name*} and executes them
     * against your database. If required, the tables and other scripts necessary to execute the project will
     * will be created.
     *
     * @param tablesToCreate a sequence of table names to create in this database, if they have not been created yet
     */
    private void initializeDatabase(String tablesToCreate) {
        File dirWithCreateTableScripts = new File("src/main/resources/database/" + getDatabaseName().toLowerCase());
        Map<String, String> scripts = new HashMap<String, String>();
        for (File scriptFile : dirWithCreateTableScripts.listFiles()) {
            String name = scriptFile.getName();
            String script = readFile(scriptFile);
            scripts.put(name.toLowerCase(), script);
        }

        if (createTables(tablesToCreate, scripts)) {
            executeScripts(scripts);
        }
    }

    /**
     * Attempts to create the required tables in your database.
     * @param scripts a map with script file names and their contents to be executed against your database.
     * @return {@code true} if tables were created with the given scripts, {@code false} if the tables already exist.
     */
    private boolean createTables(String scriptOrder, Map<String, String> scripts) {
        String[] order = scriptOrder.split(",");

        boolean tablesCreated = false;
        for (String tableName : order) {
            String createTableScript = scripts.get(tableName + ".tbl");

            try {
                jdbcTemplate.execute("select count(*) from " + tableName);
            } catch (Exception ex) {
                jdbcTemplate.execute(createTableScript);
                tablesCreated = true;
            }
        }
        return tablesCreated;
    }

    /**
     * Executes scripts (usually to create sequences and triggers if required). This script is optional and
     * it should be under a file named "scripts.sql". Each line in this file will be executed individually
     * against the your database.
     * @param scripts a map with script file names and their contents to be executed against your database.
     */
    private void executeScripts(Map<String, String> scripts) {
        String sequences = scripts.get("scripts");
        if (sequences != null) {
            for (String script : sequences.split("\\n")) {
                if (!script.trim().isEmpty()) {
                    jdbcTemplate.execute(script);
                }
            }
        }
    }

    /**
     * Reads a file line by line and returns the resulting content in a String
     * @param file the file to be read
     * @return the text content of the given file.
     */
    private String readFile(File file) {
        StringBuilder out = new StringBuilder();
        try {
            BufferedReader in = new BufferedReader(new FileReader(file));
            String str;
            while ((str = in.readLine()) != null) {
                out.append(str).append('\n');
            }
            in.close();
        } catch (IOException e) {
            throw new IllegalStateException("Error reading file " + file.getAbsolutePath(), e);
        }
        return out.toString();
    }

    /**
     * Returns the {@link javax.sql.DataSource} that provides connections to your database.
     * @return a {@link javax.sql.DataSource} for your database.
     */
    public DataSource getDataSource() {
        return jdbcTemplate.getDataSource();
    }

    /**
     * Applies database-specific configurations to an instance of {@link JdbcDataStoreConfiguration}. uniVocity tries to extract as much information
     * from your database metadata as possible. Some information might not be available from your JDBC driver so you need to provide it manually.
     *
     * Additionally, uniVocity comes with some default settings that may not be compatible with your specific JDBC driver. In such cases,
     * you need to provide your specific configurations.
     *
     * @param jdbcDataStoreConfig a pre-initialized {@link JdbcDataStoreConfiguration}, created by
     * {@link com.univocity.articles.importcities.EtlProcess#createDatabaseConfiguration()}, with
     * common settings such as batch size and generated key retrieval strategy.
     */
    public abstract void applyDatabaseSpecificConfiguration(JdbcDataStoreConfiguration jdbcDataStoreConfig);
}