com.hardcode.gdbms.engine.strategies
Class ProjectionDataSource

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

All Implemented Interfaces:

DataSource, ReadAccess

public class ProjectionDataSource
extends OperationDataSource

DataSource que añade características de proyección sobre campos al DataSource subyacente.

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

ProjectionDataSource(DataSource source, Expression[] fields, java.lang.String[] aliases)
Creates a new ProjectionDataSource object.

Method Summary

Metadata	getDataSourceMetadata() Gets the meta data about the source of this DataSource
int	getFieldCount()
int	getFieldIndexByName(java.lang.String fieldName) Obtiene el indice de un campo a partir de su nombre o -1 si no existe un campo con ese nombre
int	getFieldType(int i)
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, 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

ProjectionDataSource

public ProjectionDataSource(DataSource source,
                            Expression[] fields,
                            java.lang.String[] aliases)

Creates a new ProjectionDataSource object.

Parameters:

source - DataSource origen de la información

fields - Con los índices de los campos proyectados

aliases - Nombres asignados en la instrucción a los campos

Method Detail

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#

getFieldCount

public int getFieldCount()
                  throws DriverException

Throws:

DriverException

See Also:

com.hardcode.gdbms.data.DataSource#

getFieldIndexByName

public int getFieldIndexByName(java.lang.String fieldName)
                        throws DriverException

Description copied from interface: DataSource

Obtiene el indice de un campo a partir de su nombre o -1 si no existe un campo con ese nombre

Specified by:

getFieldIndexByName in interface DataSource

Overrides:

getFieldIndexByName in class OperationDataSource

Parameters:

fieldName - Nombre del campo

Returns:

Indice del campo con el nombre dado o -1 si el campo no existe

Throws:

DriverException - Si se produce un error accediendo a los datos

See Also:

com.hardcode.gdbms.data.DataSource#

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#

getRowCount

public long getRowCount()
                 throws DriverException

Description copied from interface: ReadAccess

Obtiene el número de registros del DataSource

Returns:

Throws:

DriverException - Si se produce algún error accediendo al DataSource

See Also:

com.hardcode.gdbms.data.DataSource#

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#

getFieldType

public int getFieldType(int i)
                 throws DriverException

Throws:

DriverException

See Also:

com.hardcode.gdbms.engine.data.driver.ObjectDriver#getFieldType(int)

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