DataSource

AI-generated Key Takeaways

• DataSource is the preferred method for obtaining database connections in Java, offering an alternative to DriverManager.

• It acts as a factory for connections to a specific physical data source and is commonly registered with a naming service using JNDI.

• DataSource implementations can provide basic connections, connection pooling, or support for distributed transactions.

• It allows for modifying connection properties without requiring code changes and does not register itself with the DriverManager.

• DataSource offers two getConnection methods, one without parameters and another accepting username and password for database authentication.

public interface DataSource implements CommonDataSource Wrapper

A factory for connections to the physical data source that this DataSource object represents. An alternative to the DriverManager facility, a DataSource object is the preferred means of getting a connection. An object that implements the DataSource interface will typically be registered with a naming service based on the Java^TM Naming and Directory (JNDI) API.

The DataSource interface is implemented by a driver vendor. There are three types of implementations:

1. Basic implementation -- produces a standard Connection object
2. Connection pooling implementation -- produces a Connection object that will automatically participate in connection pooling. This implementation works with a middle-tier connection pooling manager.
3. Distributed transaction implementation -- produces a Connection object that may be used for distributed transactions and almost always participates in connection pooling. This implementation works with a middle-tier transaction manager and almost always with a connection pooling manager.

A DataSource object has properties that can be modified when necessary. For example, if the data source is moved to a different server, the property for the server can be changed. The benefit is that because the data source's properties can be changed, any code accessing that data source does not need to be changed.

A driver that is accessed via a DataSource object does not register itself with the DriverManager. Rather, a DataSource object is retrieved though a lookup operation and then used to create a Connection object. With a basic implementation, the connection obtained through a DataSource object is identical to a connection obtained through the DriverManager facility.

Public Method Summary

abstract Connection	getConnection() Attempts to establish a connection with the data source that this DataSource object represents.
abstract Connection	getConnection(String username, String password) Attempts to establish a connection with the data source that this DataSource object represents.

Inherited Method Summary

From interface javax.sql.CommonDataSource

abstract PrintWriter	getLogWriter() Retrieves the log writer for this DataSource object.
abstract int	getLoginTimeout() Gets the maximum time in seconds that this data source can wait while attempting to connect to a database.
abstract Logger	getParentLogger() Return the parent Logger of all the Loggers used by this data source.
abstract void	setLogWriter(PrintWriter out) Sets the log writer for this DataSource object to the given java.io.PrintWriter object.
abstract void	setLoginTimeout(int seconds) Sets the maximum time in seconds that this data source will wait while attempting to connect to a database.

From interface java.sql.Wrapper

abstract boolean	isWrapperFor(Class<?> iface) Returns true if this either implements the interface argument or is directly or indirectly a wrapper for an object that does.
abstract <T> T	unwrap(Class<T> iface) Returns an object that implements the given interface to allow access to non-standard methods, or standard methods not exposed by the proxy.

Public Methods

public abstract Connection getConnection ()

Attempts to establish a connection with the data source that this DataSource object represents.

Returns

• a connection to the data source

Throws

SQLException	if a database access error occurs

public abstract Connection getConnection (String username, String password)

Attempts to establish a connection with the data source that this DataSource object represents.

Parameters

username	the database user on whose behalf the connection is being made
password	the user's password

Returns

• a connection to the data source

Throws

SQLException	if a database access error occurs