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 the configuration info needed by your app at runtime rather than at development time. Database connection info is but one of many kinds of info you might want to obtain from a JNDI server.

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 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.