com.hardcode.gdbms.engine.strategies
Class PDataSource

java.lang.Object
  com.hardcode.gdbms.engine.strategies.OperationDataSource
      com.hardcode.gdbms.engine.strategies.PDataSource

All Implemented Interfaces:

DataSource, ReadAccess

public class PDataSource
extends OperationDataSource

Clase que representa el producto cartesiano de dos o más tablas. El almacenamiento de dicha tabla se realiza en las propias tablas sobre las que se opera, haciendo los cálculos en cada acceso para saber en qué tabla y en qué posición de la tabla se encuentra el dato buscado

Author:

Fernando González Cortés

Field Summary

Fields inherited from interface com.hardcode.gdbms.engine.data.DataSource

COHERENT_ROW_ORDER, DIRECT_MODE, DISPATCH, IGNORE, STORE

Constructor Summary

PDataSource(DataSource[] tables)
Creates a new PDataSource object.

Method Summary

Metadata	getDataSourceMetadata() Gets the meta data about the source of this DataSource
int	getFieldCount()
Value	getFieldValue(long rowIndex, int fieldId) Obtiene el valor que se encuentra en la fila y columna indicada
Memento	getMemento() Gets a memento object with the current status of the DataSource
long	getRowCount() Obtiene el número de registros del DataSource
void	start() Opens the DataSource to access the data it contains.
void	stop() Closes the DataSource.

Methods inherited from class com.hardcode.gdbms.engine.strategies.OperationDataSource

addEditionListener, addField, addField, addMetadataEditionListener, addSelectionListener, beginTrans, canRedo, canUndo, check, commitTrans, deleteRow, getAlias, getAsString, getDataSourceFactory, getDispatchingMode, getDriver, getDriverMetadata, getFieldIndexByName, getFieldNames, getName, getRow, getSelectedRows, getSQL, getWhereFilter, insertEmptyRow, insertEmptyRowAt, insertFilledRow, insertFilledRowAt, isModified, redo, remove, removeEditionListener, removeField, removeMetadataEditionListener, removeSelectionListener, rollBackTrans, saveData, setAlias, setDataSourceFactory, setDispatchingMode, setFieldName, setFieldValue, setName, setSelectedRows, setSQL, undo

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

PDataSource

public PDataSource(DataSource[] tables)

Creates a new PDataSource object.

Parameters:

tables - Array de tablas que forman el producto

Throws:

DriverException

Method Detail

getFieldValue

public Value getFieldValue(long rowIndex,
                           int fieldId)
                    throws DriverException

Description copied from interface: ReadAccess

Obtiene el valor que se encuentra en la fila y columna indicada

Parameters:

rowIndex - fila

fieldId - columna

Returns:

subclase de Value con el valor del origen de datos. Never null (use ValueFactory.createNullValue() instead)

Throws:

DriverException - Si se produce un error accediendo al DataSource

See Also:

com.hardcode.gdbms.data.DataSource#getIntFieldValue(int, int)

getFieldCount

public int getFieldCount()
                  throws DriverException

Throws:

DriverException

See Also:

com.hardcode.gdbms.data.DataSource#getFieldCount()

getRowCount

public long getRowCount()

Description copied from interface: ReadAccess

Obtiene el número de registros del DataSource

Returns:

See Also:

com.hardcode.gdbms.data.DataSource#getRowCount()

start

public void start()
           throws DriverException

Description copied from interface: DataSource

Opens the DataSource to access the data it contains. If the data is accessed without a previous opening a ClosedDataSourceException is thrown. If this method is invoked twice then only the second call to stop will close the DataSource.
If the DataSource was obtained with an AUTOMATIC_OPENING mode, there's no need to open the DataSource. Indeed start calls are ignored. It's possible to close the DataSource by a single call to the close method

Throws:

DriverException - if the operation fails

See Also:

com.hardcode.gdbms.data.DataSource#open(java.io.File)

stop

public void stop()
          throws DriverException

Description copied from interface: DataSource

Closes the DataSource. After a DataSource is closed it's data cannot be retrieved. Any attempt to do so will result in a DataSourceClosedException

Throws:

DriverException - If the operation fails

See Also:

com.hardcode.gdbms.data.DataSource#close()

getMemento

public Memento getMemento()
                   throws MementoException

Description copied from interface: DataSource

Gets a memento object with the current status of the DataSource

Specified by:

getMemento in interface DataSource

Overrides:

getMemento in class OperationDataSource

Returns:

DataSourceMemento

Throws:

MementoException - If the state cannot be obtained

See Also:

DataSource.getMemento()

getDataSourceMetadata

public Metadata getDataSourceMetadata()
                               throws DriverException

Description copied from interface: DataSource

Gets the meta data about the source of this DataSource

Returns:

DataSourceMetadata

Throws:

DriverException - If cannot get the DataSource metadata