[FIXED] Hibernate: External connection config file

Issue

I currently have my Hibernate configuration file hibernate.cfg.xml in my Spring web app classpath and use Maven resources plugin to set different values for my dev and production databases like this:

reources/hibernate.cfg.xml:

<!DOCTYPE hibernate-configuration PUBLIC
        "-//Hibernate/Hibernate Configuration DTD//EN"
        "../hibernate-configuration-3.0.dtd">
<hibernate-configuration>
    <session-factory>
        <property name="hibernate.connection.driver_class">@hibernate.connection.driver_class@</property>
        <property name="hibernate.connection.url">@hibernate.connection.url@</property>
        <property name="hibernate.dialect">@hibernate.dialect@</property>
        <property name="hibernate.default_schema">@hibernate.default_schema@</property>
        <property name="hibernate.connection.username">@hibernate.connection.username@</property>
        <property name="hibernate.connection.password">@hibernate.connection.password@</property>
        <property name="hibernate.connection.requireSSL">false</property>
        <property name="hibernate.connection.autoReconnect">true</property>
        <property name="hibernate.enable_lazy_load_no_trans">true</property>
        <!--<property name="hbm2ddl.auto">update</property>-->
        <property name="hibernate.show_sql">false</property>
        <property name="hibernate.format_sql">false</property>
        <property name="hibernate.connection.CharSet">utf8</property>
        <property name="hibernate.connection.characterEncoding">utf8</property>
        <property name="hibernate.connection.useUnicode">true</property>

        <property name="hibernate.connection.provider_class">org.hibernate.c3p0.internal.C3P0ConnectionProvider</property>
        <property name="hibernate.c3p0.min_size">1</property>
        <property name="hibernate.c3p0.max_size">50</property>
        <property name="hibernate.c3p0.timeout">120</property>
        <property name="hibernate.c3p0.max_statements">50</property>
    </session-factory>
</hibernate-configuration>

pom.xml (example) :

    <profiles>
        <profile>
            <id>dev</id>
            <activation>
                <activeByDefault>true</activeByDefault>
            </activation>
            <properties>
                <hibernate.connection.driver_class>com.mysql.cj.jdbc.Driver</hibernate.connection.driver_class>
                <hibernate.connection.url>jdbc:mysql://localhost:3306/dev_db</hibernate.connection.url>
                <hibernate.dialect>org.hibernate.dialect.MySQL5Dialect</hibernate.dialect>
                <hibernate.default_schema></hibernate.default_schema>
                <hibernate.connection.username>dev_username</hibernate.connection.username>
                <hibernate.connection.password>dev_password</hibernate.connection.password>
            </properties>
        </profile>
        <profile>
            <id>deploy</id>
            <properties>
                <hibernate.connection.driver_class>com.mysql.cj.jdbc.Driver</hibernate.connection.driver_class>
                <hibernate.connection.url>jdbc:mysql://localhost:3306/deploy_db</hibernate.connection.url>
                <hibernate.dialect>org.hibernate.dialect.MySQL5Dialect</hibernate.dialect>
                <hibernate.default_schema></hibernate.default_schema>
                <hibernate.connection.username>deploy_username</hibernate.connection.username>
                <hibernate.connection.password>deploy_password</hibernate.connection.password>
            </properties>
        </profile>
    </profiles>

Those settings are loaded by a LocalSessionFactoryBean like this:

    @Bean( name = "sessionFactory" )
    public LocalSessionFactoryBean sessionFactory() {
        LocalSessionFactoryBean localSessionFactoryBean = new LocalSessionFactoryBean();
        localSessionFactoryBean.setDataSource( dataSource() );
        localSessionFactoryBean.setConfigLocation( new ClassPathResource( "hibernate.cfg.xml" ) );
        localSessionFactoryBean.setPackagesToScan( "org.example" );

        return localSessionFactoryBean;
    }

But now I need to ship software to a client who obviously won't want me to know their DB connection properties, so I want to move these properties out of my project to some local resource (like C:\MyEpicProgram\db.properties) which will be set separately in each environment (mine local, client's test server, client's deploy server etc.) and just linked to my app via JVM arguments (like -DdbConfigPath=C:\MyEpicProgram\db.properties)

So that I get something like that: db.properties:

hibernate.connection.driver_class com.mysql.cj.jdbc.Driver
hibernate.connection.url jdbc:mysql://localhost:3306/client_db
hibernate.dialect org.hibernate.dialect.MySQL5Dialect
hibernate.default_schema
hibernate.connection.username client_username
hibernate.connection.password client_password

And those will be automatically used on project startup in that environment. How can I achieve that? I've been trying to modify my session factory bean to manually set up each parameter but as of now failed to do that correctly.

Solution

So, I have solved my problem like this, taking inspiration from Flavalacious' suggestion:

@Configuration
public class DBConfig {
    private final Logger logger = Logger.getLogger( this.getClass() );

    private String dataSourceDriverClass;
    private String dataSourceDialect;
    private String dataSourceUrl;
    private String dataSourceUsername;
    private String dataSourcePassword;

    public DBConfig() {
        Properties jdbcProperties = new Properties();

        if ( System.getProperty( "dbConfigPath" ) == null )
            throw new IllegalStateException( "Property -DdbConfigPath must be provided in VM options." );

        try ( InputStream fileStream = new FileInputStream( filePath ) ) {
            // load properties from file
            jdbcProperties.load( fileStream );

            // setting properties from file to local variables for usage in various beans
            dataSourceUrl = jdbcProperties.getProperty( "url" );
            dataSourceUsername = jdbcProperties.getProperty( "username" );
            dataSourcePassword = jdbcProperties.getProperty( "password" );
            dataSourceDriverClass = jdbcProperties.getProperty( "driverClass" );
            dataSourceDialect = jdbcProperties.getProperty( "dialect" );
        } catch ( IOException e ) {
            logger.error( "Couldn't load JDBC properties." );
        }
    }

    @Bean(name = "dataSource")
    public DriverManagerDataSource dataSource() {
        DriverManagerDataSource driverManagerDataSource = new DriverManagerDataSource();

        // use loaded parameters to configure datasource
        driverManagerDataSource.setDriverClass( dataSourceDriverClass );
        driverManagerDataSource.setJdbcUrl( dataSourceUrl );
        driverManagerDataSource.setUser( dataSourceUsername );
        driverManagerDataSource.setPassword( dataSourcePassword );
        return driverManagerDataSource;
    }

    @Bean( name = "sessionFactory" )
    public LocalSessionFactoryBean sessionFactory() {
        LocalSessionFactoryBean localSessionFactoryBean = new LocalSessionFactoryBean();
        localSessionFactoryBean.setDataSource( dataSource() );
        localSessionFactoryBean.setConfigLocation( new ClassPathResource( "hibernate.cfg.xml" ) ); // the following properties are not present in this XML
        localSessionFactoryBean.setPackagesToScan( "org.example" );

        // set our properties to be discoverable by SessionFactory
        localSessionFactoryBean.getHibernateProperties().setProperty( "hibernate.connection.driver_class", dataSourceDriverClass );
        localSessionFactoryBean.getHibernateProperties().setProperty( "hibernate.connection.url", dataSourceUrl );
        localSessionFactoryBean.getHibernateProperties().setProperty( "hibernate.connection.username", dataSourceUsername );
        localSessionFactoryBean.getHibernateProperties().setProperty( "hibernate.connection.password", dataSourcePassword );
        localSessionFactoryBean.getHibernateProperties().setProperty( "hibernate.dialect", dataSourceDialect );
        if ( dataSourceDefaultSchema != null )
            localSessionFactoryBean.getHibernateProperties().setProperty( "hibernate.default_schema", dataSourceDefaultSchema );

        return localSessionFactoryBean;
    }
}

Path to the db.properties file must be provided in VM options like this: -DdbConfigPath=C:\path\to\db.properties

Answered By - Pavel Polyakoff