EclipseLink 2.2.0, build 'v20110202-r8913' API Reference

org.eclipse.persistence.queries
Class Cursor

java.lang.Object
  extended by org.eclipse.persistence.queries.Cursor
All Implemented Interfaces:
java.io.Serializable, java.util.Enumeration, java.util.Iterator
Direct Known Subclasses:
CursoredStream, ScrollableCursor

public abstract class Cursor
extends java.lang.Object
implements java.util.Enumeration, java.util.Iterator, java.io.Serializable

Purpose: Abstract class for CursoredStream and ScrolableCursor

See Also:
Serialized Form

Field Summary
protected  org.eclipse.persistence.internal.sessions.AbstractSession executionSession
          The root session that executed the call for the query.
protected  java.util.Vector<org.eclipse.persistence.internal.helper.DatabaseField> fields
          The fields expected in the result set.
protected  java.util.Map<java.lang.Object,java.lang.Object> initiallyConformingIndex
          Conforming instances found in memory when building the result.
protected  org.eclipse.persistence.internal.sessions.AbstractRecord nextRow
          Store the next row, for 1-m joining.
protected  java.util.List<java.lang.Object> objectCollection
          Internal collection of objects.
 CursorPolicy policy
          Query policy that initialize the stream.
protected  int position
          Current position in the objectCollection of the stream.
 ReadQuery query
          Read query that initialize the stream.
protected  java.sql.ResultSet resultSet
          The result set (cursor) that holds the handle to the database that the results are read from.
protected  Expression selectionCriteriaClone
          SelectionCriteria & translation row ready for incremental conforming.
protected  org.eclipse.persistence.internal.sessions.AbstractSession session
          The session that executed the query for the stream.
protected  int size
          Cached size of the stream.
protected  java.sql.Statement statement
          The preparedStatement that holds the handle to the database that the results are read from.
protected  org.eclipse.persistence.internal.sessions.AbstractRecord translationRow
           
 
Constructor Summary
Cursor()
          INTERNAL: Default constructor.
Cursor(org.eclipse.persistence.internal.databaseaccess.DatabaseCall call, CursorPolicy policy)
          INTERNAL:
 
Method Summary
protected  java.lang.Object buildAndRegisterObject(org.eclipse.persistence.internal.sessions.AbstractRecord row)
          INTERNAL: builds and registers an object from a row for cursors.
 void clear()
          PUBLIC: Release all objects read in so far.
 void close()
          PUBLIC: Closes the stream.
protected  void finalize()
          Close in case not closed.
 org.eclipse.persistence.internal.databaseaccess.DatabaseAccessor getAccessor()
          INTERNAL: Return the accessor associated with the cursor.
protected abstract  int getCursorSize()
          INTERNAL: Retrieve the size of the open cursor by executing a count on the same query as the cursor.
 org.eclipse.persistence.internal.sessions.AbstractSession getExecutionSession()
          INTERNAL: Returns the session the underlying call was executed on.
 java.util.Vector<org.eclipse.persistence.internal.helper.DatabaseField> getFields()
          INTERNAL: Return the fields for the stream.
 java.util.Map<java.lang.Object,java.lang.Object> getInitiallyConformingIndex()
          INTERNAL: Conforming instances found in memory when building the result.
 java.util.List<java.lang.Object> getObjectCollection()
          INTERNAL: Return the internal object collection that stores the objects.
 int getPageSize()
          INTERNAL: Return the number of items to be faulted in for the stream.
 CursorPolicy getPolicy()
          INTERNAL: Return the cursor policy.
abstract  int getPosition()
          INTERNAL: Return the position of the stream inside the object collection.
 ReadQuery getQuery()
          INTERNAL: Return the query associated with the stream.
 java.sql.ResultSet getResultSet()
          INTERNAL: Return the result set (cursor).
 Expression getSelectionCriteriaClone()
          INTERNAL: The clone of the selection criteria is needed for in-memory conforming each object read from the Cursor.
 org.eclipse.persistence.internal.sessions.AbstractSession getSession()
          INTERNAL: Return the handle to the session
protected  java.sql.Statement getStatement()
          INTERNAL: Return the Statement.
protected  org.eclipse.persistence.internal.sessions.AbstractRecord getTranslationRow()
          INTERNAL: Gets the translation row the query was executed with, used for incremental conforming.
 boolean isClosed()
          PUBLIC: Return if the stream is closed.
 void remove()
          PUBLIC: Remove is not support with cursors.
protected abstract  java.lang.Object retrieveNextObject()
          INTERNAL: Read the next row from the result set.
protected  void setExecutionSession(org.eclipse.persistence.internal.sessions.AbstractSession executionSession)
          INTERNAL: Sets the session the underlying call was executed on.
protected  void setFields(java.util.Vector<org.eclipse.persistence.internal.helper.DatabaseField> fields)
          INTERNAL: Set the fields for the stream.
 void setInitiallyConformingIndex(java.util.Map<java.lang.Object,java.lang.Object> index)
          INTERNAL: Conforming instances found in memory when building the result.
 void setObjectCollection(java.util.List<java.lang.Object> collection)
          INTERNAL: Set the internal object collection
 void setPolicy(CursorPolicy policy)
          INTERNAL: Set the cursor policy.
protected  void setPosition(int value)
          INTERNAL: Set the current position of the stream
protected  void setResultSet(java.sql.ResultSet result)
          INTERNAL: Set the result set (cursor)
 void setSelectionCriteriaClone(Expression expression)
          INTERNAL: The clone of the selection criteria is needed for in-memory conforming each object read from the Cursor.
 void setSession(org.eclipse.persistence.internal.sessions.AbstractSession databaseSession)
          INTERNAL: Set the session handle
 void setSize(int size)
          INTERNAL: Set the cache size
 void setTranslationRow(org.eclipse.persistence.internal.sessions.AbstractRecord row)
          INTERNAL: Sets the translation row this query was executed with.
 int size()
          PUBLIC: Retrieve the size of the open cursor by executing a count on the same query as the cursor.
 
Methods inherited from class java.lang.Object
clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 
Methods inherited from interface java.util.Enumeration
hasMoreElements, nextElement
 
Methods inherited from interface java.util.Iterator
hasNext, next
 

Field Detail

statement

protected transient java.sql.Statement statement
The preparedStatement that holds the handle to the database that the results are read from.


resultSet

protected transient java.sql.ResultSet resultSet
The result set (cursor) that holds the handle to the database that the results are read from.


session

protected transient org.eclipse.persistence.internal.sessions.AbstractSession session
The session that executed the query for the stream.


executionSession

protected transient org.eclipse.persistence.internal.sessions.AbstractSession executionSession
The root session that executed the call for the query. Knows the database platform.


fields

protected transient java.util.Vector<org.eclipse.persistence.internal.helper.DatabaseField> fields
The fields expected in the result set.


size

protected int size
Cached size of the stream.


query

public transient ReadQuery query
Read query that initialize the stream.


policy

public transient CursorPolicy policy
Query policy that initialize the stream.


objectCollection

protected java.util.List<java.lang.Object> objectCollection
Internal collection of objects.


initiallyConformingIndex

protected java.util.Map<java.lang.Object,java.lang.Object> initiallyConformingIndex
Conforming instances found in memory when building the result.


selectionCriteriaClone

protected Expression selectionCriteriaClone
SelectionCriteria & translation row ready for incremental conforming.


translationRow

protected org.eclipse.persistence.internal.sessions.AbstractRecord translationRow

nextRow

protected org.eclipse.persistence.internal.sessions.AbstractRecord nextRow
Store the next row, for 1-m joining.


position

protected int position
Current position in the objectCollection of the stream.

Constructor Detail

Cursor

public Cursor()
INTERNAL: Default constructor.


Cursor

public Cursor(org.eclipse.persistence.internal.databaseaccess.DatabaseCall call,
              CursorPolicy policy)
INTERNAL:

Method Detail

close

public void close()
           throws DatabaseException
PUBLIC: Closes the stream. This should be performed whenever the user has finished with the stream.

Throws:
DatabaseException

finalize

protected void finalize()
                 throws DatabaseException
Close in case not closed.

Overrides:
finalize in class java.lang.Object
Throws:
DatabaseException

getAccessor

public org.eclipse.persistence.internal.databaseaccess.DatabaseAccessor getAccessor()
INTERNAL: Return the accessor associated with the cursor.


getCursorSize

protected abstract int getCursorSize()
                              throws DatabaseException,
                                     QueryException
INTERNAL: Retrieve the size of the open cursor by executing a count on the same query as the cursor.

Throws:
DatabaseException
QueryException

getFields

public java.util.Vector<org.eclipse.persistence.internal.helper.DatabaseField> getFields()
INTERNAL: Return the fields for the stream.


getInitiallyConformingIndex

public java.util.Map<java.lang.Object,java.lang.Object> getInitiallyConformingIndex()
INTERNAL: Conforming instances found in memory when building the result. These objects are returned first by the cursor, and a fast lookup is needed to make sure the same objects appearing in the cursor are filtered out.


getObjectCollection

public java.util.List<java.lang.Object> getObjectCollection()
INTERNAL: Return the internal object collection that stores the objects.


getPageSize

public int getPageSize()
INTERNAL: Return the number of items to be faulted in for the stream.


getPolicy

public CursorPolicy getPolicy()
INTERNAL: Return the cursor policy.


getPosition

public abstract int getPosition()
INTERNAL: Return the position of the stream inside the object collection.


getQuery

public ReadQuery getQuery()
INTERNAL: Return the query associated with the stream.


getResultSet

public java.sql.ResultSet getResultSet()
INTERNAL: Return the result set (cursor).


getSelectionCriteriaClone

public Expression getSelectionCriteriaClone()
INTERNAL: The clone of the selection criteria is needed for in-memory conforming each object read from the Cursor.


getSession

public org.eclipse.persistence.internal.sessions.AbstractSession getSession()
INTERNAL: Return the handle to the session


getExecutionSession

public org.eclipse.persistence.internal.sessions.AbstractSession getExecutionSession()
INTERNAL: Returns the session the underlying call was executed on. This root session knows the database platform.


getStatement

protected java.sql.Statement getStatement()
INTERNAL: Return the Statement.


getTranslationRow

protected org.eclipse.persistence.internal.sessions.AbstractRecord getTranslationRow()
INTERNAL: Gets the translation row the query was executed with, used for incremental conforming.


isClosed

public boolean isClosed()
PUBLIC: Return if the stream is closed.


buildAndRegisterObject

protected java.lang.Object buildAndRegisterObject(org.eclipse.persistence.internal.sessions.AbstractRecord row)
INTERNAL: builds and registers an object from a row for cursors. Behavior is different from the query version in that refreshing is not supported.


retrieveNextObject

protected abstract java.lang.Object retrieveNextObject()
                                                throws DatabaseException
INTERNAL: Read the next row from the result set.

Throws:
DatabaseException

setFields

protected void setFields(java.util.Vector<org.eclipse.persistence.internal.helper.DatabaseField> fields)
INTERNAL: Set the fields for the stream.


setInitiallyConformingIndex

public void setInitiallyConformingIndex(java.util.Map<java.lang.Object,java.lang.Object> index)
INTERNAL: Conforming instances found in memory when building the result. These objects are returned first by the cursor, and a fast lookup is needed to make sure the same objects appearing in the cursor are filtered out.


setObjectCollection

public void setObjectCollection(java.util.List<java.lang.Object> collection)
INTERNAL: Set the internal object collection


setPolicy

public void setPolicy(CursorPolicy policy)
INTERNAL: Set the cursor policy.


setPosition

protected void setPosition(int value)
INTERNAL: Set the current position of the stream


setResultSet

protected void setResultSet(java.sql.ResultSet result)
INTERNAL: Set the result set (cursor)


setSelectionCriteriaClone

public void setSelectionCriteriaClone(Expression expression)
INTERNAL: The clone of the selection criteria is needed for in-memory conforming each object read from the Cursor.


setSession

public void setSession(org.eclipse.persistence.internal.sessions.AbstractSession databaseSession)
INTERNAL: Set the session handle


setExecutionSession

protected void setExecutionSession(org.eclipse.persistence.internal.sessions.AbstractSession executionSession)
INTERNAL: Sets the session the underlying call was executed on. This root session knows the database platform.


setSize

public void setSize(int size)
INTERNAL: Set the cache size


setTranslationRow

public void setTranslationRow(org.eclipse.persistence.internal.sessions.AbstractRecord row)
INTERNAL: Sets the translation row this query was executed with. Used for incremental conforming.


size

public int size()
         throws DatabaseException
PUBLIC: Retrieve the size of the open cursor by executing a count on the same query as the cursor. If this cursor is conforming size() can only be an estimate. cursor size plus number of conforming instances found in memory will be returned. The union (actual result) may be smaller than this.

Throws:
DatabaseException

remove

public void remove()
            throws QueryException
PUBLIC: Remove is not support with cursors.

Specified by:
remove in interface java.util.Iterator
Throws:
QueryException

clear

public void clear()
PUBLIC: Release all objects read in so far. This should be performed when reading in a large collection of objects in order to preserve memory.


EclipseLink 2.2.0, build 'v20110202-r8913' API Reference