org.springframework.jdbc.core.support

Class AbstractLobStreamingResultSetExtractor<T>

java.lang.Object

org.springframework.jdbc.core.support.AbstractLobStreamingResultSetExtractor<T>

Type Parameters:

T - the result type

All Implemented Interfaces:

ResultSetExtractor<T>

public abstract class AbstractLobStreamingResultSetExtractor<T>
extends Object
implements ResultSetExtractor<T>

Abstract ResultSetExtractor implementation that assumes streaming of LOB data. Typically used as inner class, with access to surrounding method arguments.

Delegates to the streamData template method for streaming LOB content to some OutputStream, typically using a LobHandler. Converts an IOException thrown during streaming to a LobRetrievalFailureException.

A usage example with JdbcTemplate:

JdbcTemplate jdbcTemplate = new JdbcTemplate(dataSource);  // reusable object
 final LobHandler lobHandler = new DefaultLobHandler();  // reusable object

 jdbcTemplate.query(
                 "SELECT content FROM imagedb WHERE image_name=?", new Object[] {name},
                 new AbstractLobStreamingResultSetExtractor() {
                         public void streamData(ResultSet rs) throws SQLException, IOException {
                                 FileCopyUtils.copy(lobHandler.getBlobAsBinaryStream(rs, 1), contentStream);
             }
         }
 );

Since:

1.0.2

Author:

Juergen Hoeller

See Also:

LobHandler, LobRetrievalFailureException

Constructor Summary

Constructors

Constructor and Description
AbstractLobStreamingResultSetExtractor()

Method Summary

Modifier and Type	Method and Description
T	extractData(ResultSet rs) Delegates to handleNoRowFound, handleMultipleRowsFound and streamData, according to the ResultSet state.
protected void	handleMultipleRowsFound() Handle the case where the ResultSet contains multiple rows.
protected void	handleNoRowFound() Handle the case where the ResultSet does not contain a row.
protected abstract void	streamData(ResultSet rs) Stream LOB content from the given ResultSet to some OutputStream.

Methods inherited from class java.lang.Object

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

Constructor Detail

AbstractLobStreamingResultSetExtractor

public AbstractLobStreamingResultSetExtractor()

Method Detail

extractData

@Nullable
public final T extractData(ResultSet rs)
                              throws SQLException,
                                     DataAccessException

Delegates to handleNoRowFound, handleMultipleRowsFound and streamData, according to the ResultSet state. Converts an IOException thrown by streamData to a LobRetrievalFailureException.

Specified by:

extractData in interface ResultSetExtractor<T>

Parameters:

rs - the ResultSet to extract data from. Implementations should not close this: it will be closed by the calling JdbcTemplate.

Returns:

an arbitrary result object, or null if none (the extractor will typically be stateful in the latter case).

Throws:

SQLException - if an SQLException is encountered getting column values or navigating (that is, there's no need to catch SQLException)

DataAccessException - in case of custom exceptions

See Also:

handleNoRowFound(), handleMultipleRowsFound(), streamData(java.sql.ResultSet), LobRetrievalFailureException

handleNoRowFound

protected void handleNoRowFound()
                         throws DataAccessException

Handle the case where the ResultSet does not contain a row.

Throws:

DataAccessException - a corresponding exception, by default an EmptyResultDataAccessException

See Also:

EmptyResultDataAccessException

handleMultipleRowsFound

protected void handleMultipleRowsFound()
                                throws DataAccessException

Handle the case where the ResultSet contains multiple rows.

Throws:

DataAccessException - a corresponding exception, by default an IncorrectResultSizeDataAccessException

See Also:

IncorrectResultSizeDataAccessException

streamData

protected abstract void streamData(ResultSet rs)
                            throws SQLException,
                                   IOException,
                                   DataAccessException

Stream LOB content from the given ResultSet to some OutputStream.

Typically used as inner class, with access to surrounding method arguments and to a LobHandler instance variable of the surrounding class.

Parameters:

rs - the ResultSet to take the LOB content from

Throws:

SQLException - if thrown by JDBC methods

IOException - if thrown by stream access methods

DataAccessException - in case of custom exceptions

See Also:

LobHandler.getBlobAsBinaryStream(java.sql.ResultSet, java.lang.String), FileCopyUtils