org.tentackle.persist

Class ResultSetCursor<T extends PersistentDomainObject<T>>

java.lang.Object

org.tentackle.persist.ResultSetCursor<T>

Type Parameters:

T - the retrieved type

All Implemented Interfaces:

AutoCloseable, org.tentackle.misc.ScrollableResource<T>

public class ResultSetCursor<T extends PersistentDomainObject<T>>
extends Object
implements org.tentackle.misc.ScrollableResource<T>

A cursor for a ResultSetWrapper.

Author:

harald

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	ResultSetCursor.FetchList<T> Adds a closed flag to saveObject a roundtrip in remote sessions.

Constructor Summary

Constructors

Constructor and Description
ResultSetCursor(DomainContext context, RemoteResultSetCursor<T> remoteCursor) Creates a cursor for a remote session. Constructor for pdo objects.
ResultSetCursor(T pdo, ResultSetWrapper rs) Creates a cursor for a local session.
ResultSetCursor(T pdo, ResultSetWrapper rs, JoinedSelect<T> js) Creates a cursor for a local session.

Method Summary

Modifier and Type	Method and Description
void	afterLast() Positions the cursor after the last row. Works even for empty cursors.
protected void	assertNoJoins() Asserts that there are no joins in the query.
protected void	assertSessionIsLocal() Asserts that session is local.
protected void	assertSessionIsRemote() Asserts that session is remote.
void	beforeFirst() Positions the cursor before the first row. Works even for empty cursors.
void	close() Closes the cursor. The cursor is opened in its constructor.
protected void	configureRemoteObject(T pdo) Configures the remotely retrieved PDO.
ResultSetCursor.FetchList<T>	fetch() Fetches the next objects up to the fetchsize. This method is provided to minimize the number of roundtrips especially for remote cursors.
protected void	finalize()
boolean	first() Rewinds the cursor to the first row.
T	get() Gets the data object of the current row.
DomainContext	getDomainContext() Gets the domain context.
int	getFetchDirection() Gets the fetch direction.
int	getFetchSize() Gets the fetchsize.
JoinedSelect<T>	getJoinedSelect() Gets the join configuration.
RemoteResultSetCursor<T>	getRemoteCursor() Gets the remote cursor.
ResultSetWrapper	getResultSet() Gets the result set.
int	getRow() Gets the current row. Row numbers start at 1.
org.tentackle.session.Session	getSession() Gets the session.
boolean	isAfterLast() Checks whether the cursor is after the last row.
boolean	isBeforeFirst() Checks whether the cursor is before the first row.
boolean	isClosed() Returns whether the cursor is closed.
boolean	last() Positions the cursor on the last row.
boolean	next() Moves the cursor to the next row. If there are no more rows the current row remains unchanged.
boolean	previous() Moves the cursor to the previous row. If we are already at the beginning, the cursor remains unchanged.
boolean	scroll(int rows) Moves the cursor a given number of rows.
void	setFetchDirection(int direction) Sets the fetch direction.
void	setFetchSize(int rows) Sets the fetchsize. This is the number of rows the cursor will fetch from the server in one batch.
boolean	setRow(int row) Sets the cursor to a given row. Row numbers start at 1.
List<T>	toList() Returns the objects of this cursor as a list.
protected void	toList(List<T> list) Adds the rest of the cursor to a list.
List<T>	toListAndClose() Returns the objects of this cursor as a list and closes this cursor.

Methods inherited from class java.lang.Object

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

Constructor Detail

ResultSetCursor

public ResultSetCursor(T pdo,
                       ResultSetWrapper rs,
                       JoinedSelect<T> js)

Creates a cursor for a local session.

Parameters:

pdo - the PDO proxy

rs - the result set

js - the join configuration, null if no joins

ResultSetCursor

public ResultSetCursor(T pdo,
                       ResultSetWrapper rs)

Creates a cursor for a local session.

Parameters:

pdo - the PDO proxy

rs - the result set

ResultSetCursor

public ResultSetCursor(DomainContext context,
                       RemoteResultSetCursor<T> remoteCursor)

Creates a cursor for a remote session.
Constructor for pdo objects.

Parameters:

context - the domain context

remoteCursor - the remote cursor

Method Detail

getResultSet

public ResultSetWrapper getResultSet()

Gets the result set.

Returns:

the result set

getJoinedSelect

public JoinedSelect<T> getJoinedSelect()

Gets the join configuration.

Returns:

the join configuration, null if no joins

Throws:

org.tentackle.session.PersistenceException - if session is remote

getRemoteCursor

public RemoteResultSetCursor<T> getRemoteCursor()

Gets the remote cursor.

Returns:

the remote cursor

Throws:

org.tentackle.session.PersistenceException - if session is local

getSession

public org.tentackle.session.Session getSession()

Gets the session.

Returns:

the session

getDomainContext

public DomainContext getDomainContext()

Gets the domain context.

Returns:

the context

close

public void close()

Closes the cursor.
The cursor is opened in its constructor. Closing an already closed cursor is allowed.

Specified by:

close in interface AutoCloseable

Specified by:

close in interface org.tentackle.misc.ScrollableResource<T extends PersistentDomainObject<T>>

isClosed

public boolean isClosed()

Returns whether the cursor is closed.

Specified by:

isClosed in interface org.tentackle.misc.ScrollableResource<T extends PersistentDomainObject<T>>

Returns:

true if closed

getRow

public int getRow()

Gets the current row.
Row numbers start at 1.

Specified by:

getRow in interface org.tentackle.misc.ScrollableResource<T extends PersistentDomainObject<T>>

Returns:

the current row, 0 if before first row

setRow

public boolean setRow(int row)

Sets the cursor to a given row.
Row numbers start at 1.

Specified by:

setRow in interface org.tentackle.misc.ScrollableResource<T extends PersistentDomainObject<T>>

Parameters:

row - the row number (must be ≥ 0)

Returns:

true if done, false if no such row and the cursor is now before the first row or after the last row

first

public boolean first()

Rewinds the cursor to the first row.

Specified by:

first in interface org.tentackle.misc.ScrollableResource<T extends PersistentDomainObject<T>>

Returns:

true if rewound, false if cursor is empty

last

public boolean last()

Positions the cursor on the last row.

Specified by:

last in interface org.tentackle.misc.ScrollableResource<T extends PersistentDomainObject<T>>

Returns:

true if positioned, false if cursor is empty

next

public boolean next()

Moves the cursor to the next row.
If there are no more rows the current row remains unchanged.

Specified by:

next in interface org.tentackle.misc.ScrollableResource<T extends PersistentDomainObject<T>>

Returns:

true if moved, false if no more rows

previous

public boolean previous()

Moves the cursor to the previous row.
If we are already at the beginning, the cursor remains unchanged.

Specified by:

previous in interface org.tentackle.misc.ScrollableResource<T extends PersistentDomainObject<T>>

Returns:

true if advanced, false if already at the beginning

scroll

public boolean scroll(int rows)

Moves the cursor a given number of rows.

Specified by:

scroll in interface org.tentackle.misc.ScrollableResource<T extends PersistentDomainObject<T>>

Parameters:

rows - the number of rows to move, negative to move backwards

Returns:

true if moved, false if no such row and the cursor is now positioned before the first row or after the last row

beforeFirst

public void beforeFirst()

Positions the cursor before the first row.
Works even for empty cursors.

Specified by:

beforeFirst in interface org.tentackle.misc.ScrollableResource<T extends PersistentDomainObject<T>>

afterLast

public void afterLast()

Positions the cursor after the last row.
Works even for empty cursors.

Specified by:

afterLast in interface org.tentackle.misc.ScrollableResource<T extends PersistentDomainObject<T>>

isBeforeFirst

public boolean isBeforeFirst()

Checks whether the cursor is before the first row.

Specified by:

isBeforeFirst in interface org.tentackle.misc.ScrollableResource<T extends PersistentDomainObject<T>>

Returns:

true if before first

isAfterLast

public boolean isAfterLast()

Checks whether the cursor is after the last row.

Specified by:

isAfterLast in interface org.tentackle.misc.ScrollableResource<T extends PersistentDomainObject<T>>

Returns:

true if after last

get

public T get()

Gets the data object of the current row.

Specified by:

get in interface org.tentackle.misc.ScrollableResource<T extends PersistentDomainObject<T>>

Returns:

the object, null if invalid row or no such object

toList

public List<T> toList()

Returns the objects of this cursor as a list.

Specified by:

toList in interface org.tentackle.misc.ScrollableResource<T extends PersistentDomainObject<T>>

Returns:

the list

toListAndClose

public List<T> toListAndClose()

Returns the objects of this cursor as a list and closes this cursor.

Specified by:

toListAndClose in interface org.tentackle.misc.ScrollableResource<T extends PersistentDomainObject<T>>

Returns:

the list

setFetchSize

public void setFetchSize(int rows)

Sets the fetchsize.
This is the number of rows the cursor will fetch from the server in one batch. A fetchsize of 0 means server default.

Specified by:

setFetchSize in interface org.tentackle.misc.ScrollableResource<T extends PersistentDomainObject<T>>

Parameters:

rows - the fetchsize

getFetchSize

public int getFetchSize()

Gets the fetchsize.

Specified by:

getFetchSize in interface org.tentackle.misc.ScrollableResource<T extends PersistentDomainObject<T>>

Returns:

the fetchsize

setFetchDirection

public void setFetchDirection(int direction)

Sets the fetch direction.

Parameters:

direction - the direction, see ResultSet.setFetchDirection(int).

getFetchDirection

public int getFetchDirection()

Gets the fetch direction.

Returns:

the direction

fetch

public ResultSetCursor.FetchList<T> fetch()

Fetches the next objects up to the fetchsize.
This method is provided to minimize the number of roundtrips especially for remote cursors. The cursor is closed at the end of the cursor.

Specified by:

fetch in interface org.tentackle.misc.ScrollableResource<T extends PersistentDomainObject<T>>

Returns:

the list of objects, null if no more objects found

finalize

protected void finalize()
                 throws Throwable

Overrides:

finalize in class Object

Throws:

Throwable

toList

protected void toList(List<T> list)

Adds the rest of the cursor to a list.

Parameters:

list - the list

configureRemoteObject

protected void configureRemoteObject(T pdo)

Configures the remotely retrieved PDO.

Parameters:

pdo - the PDO

assertSessionIsRemote

protected void assertSessionIsRemote()

Asserts that session is remote.

assertSessionIsLocal

protected void assertSessionIsLocal()

Asserts that session is local.

assertNoJoins

protected void assertNoJoins()

Asserts that there are no joins in the query.