How to set up JNDI DataSource with PostgreSQL?

Question

I am learning Java EE. My instructor told me to implement JNDI DataSource in my learning project. I have found some articles on the subject but I can't see clearly the steps to doing this.

My training project is a Spring MVC application. On the front end it has some Thymeleaf templates, and the data are taken from a PostgreSQL database.

What should be done to implement JNDI here? I don't even know why I need it. I was only told that this configuration should be considered obsolete and low-level, but I have no idea why.

Now the database is configured as follows:

• a props file with the following content:

driver=org.postgresql.Driver
url=jdbc:postgresql://localhost/trainingproject
dbuser=postgres
dbpassword=Password

• a .sql file which looks like this:

DROP TABLE IF EXISTS table1;
CREATE TABLE table1
(
    row1 SERIAL PRIMARY KEY,
    row2 CHARACTER VARYING(64)
);

• a DataSource bean:

@Bean
public DataSource datasource() {
    DriverManagerDataSource dataSource = new DriverManagerDataSource();
    dataSource.setDriverClassName(environment.getProperty(DRIVER));
    dataSource.setUrl(environment.getProperty(URL));
    dataSource.setUsername(environment.getProperty(USER));
    dataSource.setPassword(environment.getProperty(PASSWORD));
}

Answer 1

PGSimpleDataSource implementation of DataSource is bundled with JDBC driver.

The JDBC driver for Postgres at https://jdbc.postgresql.org includes an implementation of DataSource: PGSimpleDataSource

PGSimpleDataSource ds = new PGSimpleDataSource() ;  
ds.setServerName( "localhost" );  
ds.setDatabaseName( "your_db_name_here" );   
ds.setUser( "scott" );       
ds.setPassword( "tiger" );   

For more info:

• The Javadoc for DataSource.
• The Javadoc PGSimpleDataSource.
• My Answer to the Question, Produce a DataSource object for Postgres JDBC, programmatically
• The JDBC driver’s manual.

JNDI

Your question conflates two issues: DataSource and JNDI.

A DataSource is a simple object holding all the connection info needed to make a connection to a database. This includes a username, a password, the address of the database server, and any number of standard and proprietary feature settings. By proprietary, I mean Postgres-specific feature settings versus Microsoft SQL Server-specific versus Oracle-specific, etc. Look at the Javadoc for DataSource to see how simple it is, basically just a getConnection method. You can obtain a DataSource object with or without JNDI; the two are orthogonal issues.

JNDI is much more complex. JNDI is an interface for obtaining from a naming/directory server the configuration info needed by your app at runtime. Using this interface to such a server means you need not include deployment details in your codebase; you look up needed details on-the-fly at runtime.

Database connection info is but one of many kinds of info you might want to obtain from a JNDI server. You might also look up web services servers, logging services, and so on.

So rather than hard-coding your database connection info, you might want to “discover” the proper database connection info when launching your app. Your testing machines will use a bogus database server while your production deployment machines will use a different database server. These database servers may not be known to the programmer at compile time, or may not even exist yet. A look-up needs to be done, and JNDI is a standard way to do so without vendor lock-in.

How you configure database connection info to be delivered by a JNDI-compliant naming/directory server as a DataSource object to your app differs wildly depending on the particular server environment of your enterprise. Given your last code example, it looks like you are not actually accessing a JNDI server in your class, so JNDI is moot.