How to get a DataSource?

Question

I'm not certain how to get a DataSource object. I was able to use the DriverManager method to obtain a connection to a SQL database running on localhost, but every time I try to use the DataSource method to do so I wind up getting exceptions (mostly for naming).

What I was wondering is:

1. Is it possible to get a DataSource object for local hosted databases?
2. Does the DataSource class need to be published, or is it like DriverManager where you just get a connection with no new class creation?
3. Could you show an example?

Answer 1

A DataSource allows getting a JDBC connection mostly from a pool of connections. A DataSource object represents a particular DBMS or some other data source, such as a file. If a company uses more than one data source, it will deploy a separate DataSource object for each of them. The DataSource interface is implemented by a driver vendor. You externalize DB connection properties file and fetch the object using JNDI. Using a Datasource you need to know only the JNDI name. The Application server cares about the details.

It can be implemented in three different ways:

1. A basic DataSource implementation produces standard Connection objects that are not pooled or used in a distributed transaction.
2. A DataSource implementation that supports connection pooling produces Connection objects that participate in connection pooling, that is, connections that can be recycled.
3. A DataSource implementation that supports distributed transactions produces Connection objects that can be used in a distributed transaction, that is, a transaction that accesses two or more DBMS servers.

Like, in Spring, you can configure the datasource in an XML file and then (1) either inject it into your bean, (2) get it from ApplicationContext.

DataSource ds = (DataSource) ApplicationContextProvider.
                            getApplicationContext().getBean("myDataSource");
Connection c = ds.getConnection();

Suggested Reading:

1. Connecting with DataSource Objects
2. Why do we use a DataSource instead of a DriverManager?
3. Data access with JDBC
4. How to retrieve DB connection using DataSource without JNDI?
5. Best way to manage DB connections without JNDI