org.springframework.jdbc.support.lob
Class OracleLobHandler

java.lang.Object
  org.springframework.jdbc.support.lob.AbstractLobHandler
      org.springframework.jdbc.support.lob.OracleLobHandler

All Implemented Interfaces:

LobHandler

public class OracleLobHandler
extends AbstractLobHandler

LobHandler implementation for Oracle databases. Uses proprietary API to create oracle.sql.BLOB and oracle.sql.CLOB instances, as necessary when working with Oracle's JDBC driver. Note that this LobHandler requires Oracle JDBC driver 9i or higher!

While most databases are able to work with DefaultLobHandler, Oracle just accepts Blob/Clob instances created via its own proprietary BLOB/CLOB API, and additionally doesn't accept large streams for PreparedStatement's corresponding setter methods. Therefore, you need to use a strategy like this LobHandler implementation.

Needs to work on a native JDBC Connection, to be able to cast it to oracle.jdbc.OracleConnection. If you pass in Connections from a connection pool (the usual case in a J2EE environment), you need to set an appropriate NativeJdbcExtractor to allow for automatical retrieval of the underlying native JDBC Connection. LobHandler and NativeJdbcExtractor are separate concerns, therefore they are represented by separate strategy interfaces.

Coded via reflection to avoid dependencies on Oracle classes. Even reads in Oracle constants via reflection because of different Oracle drivers (classes12, ojdbc14, ojdbc5, ojdbc6) having different constant values! As this LobHandler initializes Oracle classes on instantiation, do not define this as eager-initializing singleton if you do not want to depend on the Oracle JAR being in the class path: use "lazy-init=true" to avoid this issue.

Since:

04.12.2003

Author:

Juergen Hoeller, Thomas Risberg

See Also:

setNativeJdbcExtractor(org.springframework.jdbc.support.nativejdbc.NativeJdbcExtractor), oracle.sql.BLOB, oracle.sql.CLOB

Nested Class Summary

protected static interface	OracleLobHandler.LobCallback Internal callback interface for use with createLob.
protected class	OracleLobHandler.OracleLobCreator LobCreator implementation for Oracle databases.

Field Summary

protected Log

logger

Constructor Summary

OracleLobHandler()

Method Summary

InputStream	getBlobAsBinaryStream(ResultSet rs, int columnIndex) Retrieve the given column as binary stream from the given ResultSet.
byte[]	getBlobAsBytes(ResultSet rs, int columnIndex) Retrieve the given column as bytes from the given ResultSet.
InputStream	getClobAsAsciiStream(ResultSet rs, int columnIndex) Retrieve the given column as ASCII stream from the given ResultSet.
Reader	getClobAsCharacterStream(ResultSet rs, int columnIndex) Retrieve the given column as character stream from the given ResultSet.
String	getClobAsString(ResultSet rs, int columnIndex) Retrieve the given column as String from the given ResultSet.
LobCreator	getLobCreator() Create a new LobCreator instance, i.e.
protected void	initializeResourcesBeforeRead(Connection con, Object lob) Initialize any LOB resources before a read is done.
protected void	initOracleDriverClasses(Connection con) Retrieve the oracle.sql.BLOB and oracle.sql.CLOB classes via reflection, and initialize the values for the DURATION_SESSION, MODE_READWRITE and MODE_READONLY constants defined there.
protected void	releaseResourcesAfterRead(Connection con, Object lob) Release any LOB resources after read is complete.
void	setCache(boolean cache) Set whether to cache the temporary LOB in the buffer cache.
void	setNativeJdbcExtractor(NativeJdbcExtractor nativeJdbcExtractor) Set an appropriate NativeJdbcExtractor to be able to retrieve the underlying native oracle.jdbc.OracleConnection.
void	setReleaseResourcesAfterRead(boolean releaseResources) Set whether to agressively release any resources used by the LOB.

Methods inherited from class org.springframework.jdbc.support.lob.AbstractLobHandler

getBlobAsBinaryStream, getBlobAsBytes, getClobAsAsciiStream, getClobAsCharacterStream, getClobAsString

Methods inherited from class java.lang.Object

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

Field Detail

logger

protected final Log logger

Constructor Detail

OracleLobHandler

public OracleLobHandler()

Method Detail

setNativeJdbcExtractor

public void setNativeJdbcExtractor(NativeJdbcExtractor nativeJdbcExtractor)

Set an appropriate NativeJdbcExtractor to be able to retrieve the underlying native oracle.jdbc.OracleConnection. This is necessary for DataSource-based connection pools, as those need to return wrapped JDBC Connection handles that cannot be cast to a native Connection implementation.

Effectively, this LobHandler just invokes a single NativeJdbcExtractor method, namely getNativeConnectionFromStatement with a PreparedStatement argument (falling back to a PreparedStatement.getConnection() call if no extractor is set).

A common choice is SimpleNativeJdbcExtractor, whose Connection unwrapping (which is what OracleLobHandler needs) will work with many connection pools. See SimpleNativeJdbcExtractor's javadoc for details.

See Also:

NativeJdbcExtractor.getNativeConnectionFromStatement(java.sql.Statement), SimpleNativeJdbcExtractor, oracle.jdbc.OracleConnection

setCache

public void setCache(boolean cache)

Set whether to cache the temporary LOB in the buffer cache. This value will be passed into BLOB/CLOB.createTemporary.

Default is true.

See Also:

oracle.sql.BLOB#createTemporary, oracle.sql.CLOB#createTemporary

setReleaseResourcesAfterRead

public void setReleaseResourcesAfterRead(boolean releaseResources)

Set whether to agressively release any resources used by the LOB. If set to true then you can only read the LOB values once. Any subsequent reads will fail since the resources have been closed.

Setting this property to true can be useful when your queries generates large temporary LOBs that occupy space in the TEMPORARY tablespace or when you want to free up any memory allocated by the driver for the LOB reading.

Default is false.

Since:

3.0

See Also:

oracle.sql.BLOB#freeTemporary, oracle.sql.CLOB#freeTemporary, oracle.sql.BLOB#open, oracle.sql.CLOB#open, oracle.sql.BLOB#close, oracle.sql.CLOB#close

initOracleDriverClasses

protected void initOracleDriverClasses(Connection con)

Retrieve the oracle.sql.BLOB and oracle.sql.CLOB classes via reflection, and initialize the values for the DURATION_SESSION, MODE_READWRITE and MODE_READONLY constants defined there.

Parameters:

con - the Oracle Connection, for using the exact same class loader that the Oracle driver was loaded with

See Also:

oracle.sql.BLOB#DURATION_SESSION, oracle.sql.BLOB#MODE_READWRITE, oracle.sql.BLOB#MODE_READONLY, oracle.sql.CLOB#DURATION_SESSION, oracle.sql.CLOB#MODE_READWRITE, oracle.sql.CLOB#MODE_READONLY

getBlobAsBytes

public byte[] getBlobAsBytes(ResultSet rs,
                             int columnIndex)
                      throws SQLException

Description copied from interface: LobHandler

Retrieve the given column as bytes from the given ResultSet. Might simply invoke ResultSet.getBytes or work with ResultSet.getBlob, depending on the database and driver.

Parameters:

rs - the ResultSet to retrieve the content from

columnIndex - the column index to use

Returns:

the content as byte array, or null in case of SQL NULL

Throws:

SQLException - if thrown by JDBC methods

See Also:

ResultSet.getBytes(int)

getBlobAsBinaryStream

public InputStream getBlobAsBinaryStream(ResultSet rs,
                                         int columnIndex)
                                  throws SQLException

Description copied from interface: LobHandler

Retrieve the given column as binary stream from the given ResultSet. Might simply invoke ResultSet.getBinaryStream or work with ResultSet.getBlob, depending on the database and driver.

Parameters:

rs - the ResultSet to retrieve the content from

columnIndex - the column index to use

Returns:

the content as binary stream, or null in case of SQL NULL

Throws:

SQLException - if thrown by JDBC methods

See Also:

ResultSet.getBinaryStream(int)

getClobAsString

public String getClobAsString(ResultSet rs,
                              int columnIndex)
                       throws SQLException

Description copied from interface: LobHandler

Retrieve the given column as String from the given ResultSet. Might simply invoke ResultSet.getString or work with ResultSet.getClob, depending on the database and driver.

Parameters:

rs - the ResultSet to retrieve the content from

columnIndex - the column index to use

Returns:

the content as String, or null in case of SQL NULL

Throws:

SQLException - if thrown by JDBC methods

See Also:

ResultSet.getString(int)

getClobAsAsciiStream

public InputStream getClobAsAsciiStream(ResultSet rs,
                                        int columnIndex)
                                 throws SQLException

Description copied from interface: LobHandler

Retrieve the given column as ASCII stream from the given ResultSet. Might simply invoke ResultSet.getAsciiStream or work with ResultSet.getClob, depending on the database and driver.

Parameters:

rs - the ResultSet to retrieve the content from

columnIndex - the column index to use

Returns:

the content as ASCII stream, or null in case of SQL NULL

Throws:

SQLException - if thrown by JDBC methods

See Also:

ResultSet.getAsciiStream(int)

getClobAsCharacterStream

public Reader getClobAsCharacterStream(ResultSet rs,
                                       int columnIndex)
                                throws SQLException

Description copied from interface: LobHandler

Retrieve the given column as character stream from the given ResultSet. Might simply invoke ResultSet.getCharacterStream or work with ResultSet.getClob, depending on the database and driver.

Parameters:

rs - the ResultSet to retrieve the content from

columnIndex - the column index to use

Returns:

the content as character stream

Throws:

SQLException - if thrown by JDBC methods

See Also:

ResultSet.getCharacterStream(int)

getLobCreator

public LobCreator getLobCreator()

Description copied from interface: LobHandler

Create a new LobCreator instance, i.e. a session for creating BLOBs and CLOBs. Needs to be closed after the created LOBs are not needed anymore - typically after statement execution or transaction completion.

Returns:

the new LobCreator instance

See Also:

LobCreator.close()

initializeResourcesBeforeRead

protected void initializeResourcesBeforeRead(Connection con,
                                             Object lob)

Initialize any LOB resources before a read is done.

This implementation calls BLOB.open(BLOB.MODE_READONLY) or CLOB.open(CLOB.MODE_READONLY) on any non-temporary LOBs if releaseResourcesAfterRead property is set to true.

This method can be overridden by sublcasses if different behavior is desired.

Parameters:

con - the connection to be usde for initilization

lob - the LOB to initialize

releaseResourcesAfterRead

protected void releaseResourcesAfterRead(Connection con,
                                         Object lob)

Release any LOB resources after read is complete.

If releaseResourcesAfterRead property is set to true then this implementation calls BLOB.close() or CLOB.close() on any non-temporary LOBs that are open or BLOB.freeTemporary() or CLOB.freeTemporary() on any temporary LOBs.

This method can be overridden by sublcasses if different behavior is desired.

Parameters:

con - the connection to be usde for initilization

lob - the LOB to initialize