Package com.feedzai.commons.sql.abstraction.dml.result

Class ResultIterator

java.lang.Object

com.feedzai.commons.sql.abstraction.dml.result.ResultIterator

All Implemented Interfaces:

AutoCloseable

Direct Known Subclasses:

DB2ResultIterator, H2ResultIterator, MySqlResultIterator, OracleResultIterator, PostgreSqlResultIterator, SqlServerResultIterator

public abstract class ResultIterator
extends Object
implements AutoCloseable

The abstract result iterator. Extending classes will create the specific ResultColumn implementation given the engine in place.

Since:

2.0.0

Author:

Rui Vilao (rui.vilao@feedzai.com)

Constructor Summary

Constructors

Constructor	Description
ResultIterator(PreparedStatement statement)	Creates a new instance of ResultIterator for PreparedStatement.
ResultIterator(Statement statement, String sql)	Creates a new instance of ResultIterator for regular Statement.

Method Summary

Modifier and Type	Method	Description
boolean	cancel()	Attempts to cancel the current query.
void	close()	Closes the ResultSet and the Statement if applicable.
abstract ResultColumn	createResultColumn(String name, Object value)	Creates a ResultColumn for the given engine in place.
List<String>	getColumnNames()	Retrieves the column names of the iterator.
int	getCurrentRowCount()	Retrieves the number of rows processed by the iterator so far.
protected QueryExceptionHandler	getQueryExceptionHandler()	Gets the instance of QueryExceptionHandler to be used in disambiguating SQL exceptions.
boolean	isClosed()	Checks if this result iterator is closed.
Map<String,ResultColumn>	next()	Retrieves the next row in the result set.
ResultColumn[]	nextResult()	Retrieves the values of the next row in the result set as an array of objects.

Methods inherited from class java.lang.Object

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

Constructor Detail

ResultIterator

public ResultIterator(Statement statement,
                      String sql)
               throws DatabaseEngineException

Creates a new instance of ResultIterator for regular Statement.

Parameters:

statement - The statement.

sql - The SQL sentence.

Throws:

DatabaseEngineException - If a database access error occurs.

ResultIterator

public ResultIterator(PreparedStatement statement)
               throws DatabaseEngineException

Creates a new instance of ResultIterator for PreparedStatement.

Parameters:

statement - The prepared statement.

Throws:

DatabaseEngineException - If a database access error occurs.

Method Detail

getCurrentRowCount

public int getCurrentRowCount()

Retrieves the number of rows processed by the iterator so far. If the iteration hasn't started, this method returns 0.

Returns:

The number of rows processed by the iterator so far or 0 if the iteration hasn't started.

next

public Map<String,ResultColumn> next()
                                    throws DatabaseEngineException

Retrieves the next row in the result set.

This method also closes the result set upon the last call on the result set.

If the statement in place is not a PreparedStatement it also closes the statement.

If an exception is thrown the calling thread is responsible for repeating the action in place.

Returns:

The result row.

Throws:

DatabaseEngineException - If a database access error occurs.

nextResult

public ResultColumn[] nextResult()
                          throws DatabaseEngineException

Retrieves the values of the next row in the result set as an array of objects.

This method provides an optimized version of the next() method with less overhead.

This method also closes the result set upon the last call on the result set.

If the statement in place is not a PreparedStatement it also closes the statement.

If an exception is thrown the calling thread is responsible for repeating the action in place.

Returns:

The result row.

Throws:

DatabaseEngineException - If a database access error occurs.

See Also:

for the names of the columns of this method return.

isClosed

public boolean isClosed()

Checks if this result iterator is closed.

Returns:

true if the result set is closed, false otherwise.

getColumnNames

public List<String> getColumnNames()

Retrieves the column names of the iterator.

Returns:

the column names of the iterator.

cancel

public boolean cancel()

Attempts to cancel the current query. This relies on the JDBC driver supporting Statement.cancel(), which is not guaranteed on all drivers. A possible use case for this method is to implement a timeout; If that's the case, see also AbstractDatabaseEngine.iterator(String, int, int) for an alternative way to accomplish this. This method is expected to be invoked from a thread distinct of the one that is reading from the result set.

Returns:

true if the query was cancelled, false otherwise.

close

public void close()

Closes the ResultSet and the Statement if applicable.

Specified by:

close in interface AutoCloseable

createResultColumn

public abstract ResultColumn createResultColumn(String name,
                                                Object value)

Creates a ResultColumn for the given engine in place.

Parameters:

name - The name of the column.

value - The value on the column.

Returns:

A specific result column given the implementation.

getQueryExceptionHandler

protected QueryExceptionHandler getQueryExceptionHandler()

Gets the instance of QueryExceptionHandler to be used in disambiguating SQL exceptions.

Returns:

the QueryExceptionHandler.

Since:

2.5.1