# Interface DataSource

All Superinterfaces:
  `CommonDataSource, Wrapper`

public interface DataSource extends 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 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 through 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.

An implementation of `DataSource` must include a public no-arg constructor.

Since:
  1.4

- ## Method Summary

  Modifier and Type
  Method
  Description
  `default ConnectionBuilder`
  `createConnectionBuilder()`
  Create a new `ConnectionBuilder` instance
  `Connection`
  `getConnection()`
  Attempts to establish a connection with the data source that this `DataSource` object represents.
  `Connection`
  `getConnection(String username, String password)`
  Attempts to establish a connection with the data source that this `DataSource` object represents.
  `int`
  `getLoginTimeout()`
  Gets the maximum time in seconds that this data source can wait while attempting to connect to a database.
  `PrintWriter`
  `getLogWriter()`
  Retrieves the log writer for this `DataSource` object.
  `void`
  `setLoginTimeout(int seconds)`
  Sets the maximum time in seconds that this data source will wait while attempting to connect to a database.
  `void`
  `setLogWriter(PrintWriter out)`
  Sets the log writer for this `DataSource` object to the given `java.io.PrintWriter` object.

  ### Methods declared in interface CommonDataSource

  `createShardingKeyBuilder, getParentLogger`
  Modifier and Type
  Method
  Description
  `default ShardingKeyBuilder`
  `createShardingKeyBuilder()`
  Creates a new `ShardingKeyBuilder` instance
  `Logger`
  `getParentLogger()`
  Return the parent Logger of all the Loggers used by this data source.

  ### Methods declared in interface Wrapper

  `isWrapperFor, unwrap`
  Modifier and Type
  Method
  Description
  `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.
  `<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.

- ## Method Details

  - ### getConnection

    Connection getConnection() throws SQLException

    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
      `SQLTimeoutException` - when the driver has determined that the timeout value specified by the `setLoginTimeout` method has been exceeded and has at least tried to cancel the current database connection attempt

  - ### getConnection

    Connection getConnection(String username, String password) throws SQLException

    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
      `SQLTimeoutException` - when the driver has determined that the timeout value specified by the `setLoginTimeout` method has been exceeded and has at least tried to cancel the current database connection attempt
    Since:
      1.4

  - ### getLogWriter

    PrintWriter getLogWriter() throws SQLException

    Retrieves the log writer for this `DataSource` object.

    The log writer is a character output stream to which all logging and tracing messages for this data source will be printed. This includes messages printed by the methods of this object, messages printed by methods of other objects manufactured by this object, and so on. Messages printed to a data source specific log writer are not printed to the log writer associated with the `java.sql.DriverManager` class. When a `DataSource` object is created, the log writer is initially null; in other words, the default is for logging to be disabled.

    Specified by:
      `getLogWriter` in interface `CommonDataSource`
    Returns:
      the log writer for this data source or null if logging is disabled
    Throws:
      `SQLException` - if a database access error occurs
    Since:
      1.4
    See Also:
      - `CommonDataSource.setLogWriter(PrintWriter)`

  - ### setLogWriter

    void setLogWriter(PrintWriter out) throws SQLException

    Sets the log writer for this `DataSource` object to the given `java.io.PrintWriter` object.

    The log writer is a character output stream to which all logging and tracing messages for this data source will be printed. This includes messages printed by the methods of this object, messages printed by methods of other objects manufactured by this object, and so on. Messages printed to a data source- specific log writer are not printed to the log writer associated with the `java.sql.DriverManager` class. When a `DataSource` object is created the log writer is initially null; in other words, the default is for logging to be disabled.

    Specified by:
      `setLogWriter` in interface `CommonDataSource`
    Parameters:
      `out` - the new log writer; to disable logging, set to null
    Throws:
      `SQLException` - if a database access error occurs
    Since:
      1.4
    See Also:
      - `CommonDataSource.getLogWriter()`

  - ### setLoginTimeout

    void setLoginTimeout(int seconds) throws SQLException

    Sets the maximum time in seconds that this data source will wait while attempting to connect to a database. A value of zero specifies that the timeout is the default system timeout if there is one; otherwise, it specifies that there is no timeout. When a `DataSource` object is created, the login timeout is initially zero.

    Specified by:
      `setLoginTimeout` in interface `CommonDataSource`
    Parameters:
      `seconds` - the data source login time limit
    Throws:
      `SQLException` - if a database access error occurs.
    Since:
      1.4
    See Also:
      - `CommonDataSource.getLoginTimeout()`

  - ### getLoginTimeout

    int getLoginTimeout() throws SQLException
    Gets the maximum time in seconds that this data source can wait while attempting to connect to a database. A value of zero means that the timeout is the default system timeout if there is one; otherwise, it means that there is no timeout. When a `DataSource` object is created, the login timeout is initially zero.
    Specified by:
      `getLoginTimeout` in interface `CommonDataSource`
    Returns:
      the data source login time limit
    Throws:
      `SQLException` - if a database access error occurs.
    Since:
      1.4
    See Also:
      - `CommonDataSource.setLoginTimeout(int)`

  - ### createConnectionBuilder

    default ConnectionBuilder createConnectionBuilder() throws SQLException
    Create a new `ConnectionBuilder` instance
    Implementation Requirements:
      The default implementation will throw a `SQLFeatureNotSupportedException`
    Returns:
      The ConnectionBuilder instance that was created
    Throws:
      `SQLException` - if an error occurs creating the builder
      `SQLFeatureNotSupportedException` - if the driver does not support sharding
    Since:
      9
    See Also:
      - `ConnectionBuilder`