Spring Framework

org.springframework.jdbc.core.support
Class AbstractLobStreamingResultSetExtractor

java.lang.Object
  extended by org.springframework.jdbc.core.support.AbstractLobStreamingResultSetExtractor
All Implemented Interfaces:
ResultSetExtractor

public abstract class AbstractLobStreamingResultSetExtractor
extends java.lang.Object
implements ResultSetExtractor

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
AbstractLobStreamingResultSetExtractor()
           
 
Method Summary
 java.lang.Object extractData(java.sql.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(java.sql.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

public final java.lang.Object extractData(java.sql.ResultSet rs)
                                   throws java.sql.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
Parameters:
rs - 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:
java.sql.SQLException - if a 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(java.sql.ResultSet rs)
                            throws java.sql.SQLException,
                                   java.io.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:
java.sql.SQLException - if thrown by JDBC methods
java.io.IOException - if thrown by stream access methods
DataAccessException - in case of custom exceptions
See Also:
LobHandler.getBlobAsBinaryStream(java.sql.ResultSet, java.lang.String), FileCopyUtils

Spring Framework