Package 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:

  • Constructor Details

    • AbstractLobStreamingResultSetExtractor

      public AbstractLobStreamingResultSetExtractor()

  • Method Details

    • extractData

      @Nullable public final T extractData(ResultSet rs) throws SQLException, org.springframework.dao.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)
      org.springframework.dao.DataAccessException - in case of custom exceptions
      See Also:

    • handleNoRowFound

      protected void handleNoRowFound() throws org.springframework.dao.DataAccessException
      Handle the case where the ResultSet does not contain a row.
      Throws:
      org.springframework.dao.DataAccessException - a corresponding exception, by default an EmptyResultDataAccessException
      See Also:
      • EmptyResultDataAccessException

    • handleMultipleRowsFound

      protected void handleMultipleRowsFound() throws org.springframework.dao.DataAccessException
      Handle the case where the ResultSet contains multiple rows.
      Throws:
      org.springframework.dao.DataAccessException - a corresponding exception, by default an IncorrectResultSizeDataAccessException
      See Also:
      • IncorrectResultSizeDataAccessException

    • streamData

      protected abstract void streamData(ResultSet rs) throws SQLException, IOException, org.springframework.dao.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
      org.springframework.dao.DataAccessException - in case of custom exceptions
      See Also: