SQL92StatementIterator

Overview

Package

Class

Use

Deprecated

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nl.aidministrator.rdf.sail.sql92.iterators
Class SQL92StatementIterator

java.lang.Object
  nl.aidministrator.rdf.sail.sql92.iterators.SQL92StatementIterator

All Implemented Interfaces:: nl.aidministrator.rdf.sail.StatementIterator

public class SQL92StatementIterator
extends java.lang.Object
implements nl.aidministrator.rdf.sail.StatementIterator

A StatementIterator that executes an SQL query. The ResultSet should contain 6 columns: namespace(String) and localname(String) of subject, namespace(String) and localname(String) of predicate and namespace(String), localname(String) if object is instance of rdfs:Resource or language(String) and value(String) if object is instance of rdfs:Literal. With getObject() a StatementIterator returns the object of the statement it is pointing at. An object can be of type rdfs:Resource or rdfs:Literal, therefore it should know whether to construct a Resource or a Literal out of the ResultSet. A way to establish this is to execute 2 queries, one where object of table triples is joined with id of table resources and one where it is joined with id of table literals. Boolean _literalsHasBeenQueried identifies which query is executed, so whether to construct a Resource or a Literal out of the ResultSet.

Version:: 1.1, 01/17/02

Field Summary

protected java.sql.Connection _databaseCon
          Connection to the database.

protected boolean _hasNext
          Flag indicating whether there are any more results.

protected boolean _literalsHasBeenQueried
          Indicates which query is executed.

protected nl.aidministrator.rdf.sail.model.Value _nextObject
          Object of statement iterator is currently pointing at.

protected nl.aidministrator.rdf.sail.model.Resource _nextPredicate
          Predicate of statement iterator is currently pointing at.

protected nl.aidministrator.rdf.sail.model.Resource _nextSubject
          Subject of statement iterator is currently pointing at.

protected boolean _objectFixed
          Is object fixed.

protected boolean _predicateFixed
          Is predicate fixed.

protected java.lang.String _queryLiterals
          The query to execute.

protected java.lang.String _queryResources
          The query to execute.

protected java.sql.ResultSet _resultSet
          ResultSet for the query.

protected java.sql.Statement _statement
          SQL statement that was used to generate the ResultSet.

protected boolean _subjectFixed
          Is subject fixed.

Constructor Summary

SQL92StatementIterator(java.sql.Connection databaseCon, java.lang.String queryResources, java.lang.String queryLiterals, nl.aidministrator.rdf.sail.model.Resource subject, nl.aidministrator.rdf.sail.model.Resource predicate, nl.aidministrator.rdf.sail.model.Value object)
          Constructor.

Method Summary

private void _execQuery(java.lang.String query)


private void _proceed()


void close()
          Closes the iterator and frees any resources that it uses (e.g.

protected void finalize()
          Called by the garbage collector on SQL92ValueIterator when garbage collection determines that there are no more references to the SQL92ValueIterator.

nl.aidministrator.rdf.sail.model.Value getObject()
          Gets the object of the current statement.

nl.aidministrator.rdf.sail.model.Resource getPredicate()
          Gets the predicate of the current statement.

nl.aidministrator.rdf.sail.model.Resource getSubject()
          Gets the subject of the current statement.

boolean hasNext()
          Checks whether there are any more statements available.

void next()
          Go to the next statement.

Methods inherited from class java.lang.Object

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

Field Detail

_resultSet

protected java.sql.ResultSet _resultSet

ResultSet for the query.

_statement

protected java.sql.Statement _statement

SQL statement that was used to generate the ResultSet. It cannot be closed until all results have been read from the ResultSet.

_databaseCon

protected java.sql.Connection _databaseCon

Connection to the database.

_queryResources

protected java.lang.String _queryResources

The query to execute.

_queryLiterals

protected java.lang.String _queryLiterals

The query to execute.

_hasNext

protected boolean _hasNext

Flag indicating whether there are any more results.

_nextSubject

protected nl.aidministrator.rdf.sail.model.Resource _nextSubject

Subject of statement iterator is currently pointing at.

_nextPredicate

protected nl.aidministrator.rdf.sail.model.Resource _nextPredicate

Predicate of statement iterator is currently pointing at.

_nextObject

protected nl.aidministrator.rdf.sail.model.Value _nextObject

Object of statement iterator is currently pointing at.

_subjectFixed

protected boolean _subjectFixed

Is subject fixed.

_predicateFixed

protected boolean _predicateFixed

Is predicate fixed.

_objectFixed

protected boolean _objectFixed

Is object fixed.

_literalsHasBeenQueried

protected boolean _literalsHasBeenQueried

Indicates which query is executed.

Constructor Detail

SQL92StatementIterator

public SQL92StatementIterator(java.sql.Connection databaseCon,
                              java.lang.String queryResources,
                              java.lang.String queryLiterals,
                              nl.aidministrator.rdf.sail.model.Resource subject,
                              nl.aidministrator.rdf.sail.model.Resource predicate,
                              nl.aidministrator.rdf.sail.model.Value object)

Constructor.

Method Detail

_proceed

private void _proceed()