Package org.eclipse.persistence.queries

Class Cursor

java.lang.Object
org.eclipse.persistence.queries.Cursor
All Implemented Interfaces:
Serializable, Enumeration, Iterator
Direct Known Subclasses:
CursoredStream, ScrollableCursor
public abstract class Cursor extends Object implements Enumeration, Iterator, Serializable

Purpose: Abstract class for CursoredStream and ScrolableCursor

See Also:

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    protected org.eclipse.persistence.internal.sessions.AbstractSession
    executionSession
    The root session that executed the call for the query.
    protected Vector<org.eclipse.persistence.internal.helper.DatabaseField>
    fields
    The fields expected in the result set.
    protected Map<Object,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 List<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 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 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

    Constructors
    Constructor
    Description
    Cursor()
    INTERNAL: Default constructor.
    Cursor(org.eclipse.persistence.internal.databaseaccess.DatabaseCall call, CursorPolicy policy)
    INTERNAL:

  • Method Summary

    Modifier and Type
    Method
    Description
    protected 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.
    Vector<org.eclipse.persistence.internal.helper.DatabaseField>
    getFields()
    INTERNAL: Return the fields for the stream.
    Map<Object,Object>
    getInitiallyConformingIndex()
    INTERNAL: Conforming instances found in memory when building the result.
    List<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.
    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 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 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(Vector<org.eclipse.persistence.internal.helper.DatabaseField> fields)
    INTERNAL: Set the fields for the stream.
    void
    setInitiallyConformingIndex(Map<Object,Object> index)
    INTERNAL: Conforming instances found in memory when building the result.
    void
    setObjectCollection(List<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(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

    forEachRemaining, hasNext, next

  • Field Details

    • statement

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

    • resultSet

      protected transient 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 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 List<Object> objectCollection
      Internal collection of objects.

    • initiallyConformingIndex

      protected Map<Object,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 Details

    • Cursor

      public Cursor()
      INTERNAL: Default constructor.

    • Cursor

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

  • Method Details

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

    • getInitiallyConformingIndex

      public Map<Object,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 List<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 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 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 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 Object retrieveNextObject() throws DatabaseException
      INTERNAL: Read the next row from the result set.
      Throws:
      DatabaseException

    • setFields

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

    • setInitiallyConformingIndex

      public void setInitiallyConformingIndex(Map<Object,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(List<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(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 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.