OracleLobHandler (Spring Framework)

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org.springframework.jdbc.support.lob
Class OracleLobHandler

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

All Implemented Interfaces:: LobHandler

public class OracleLobHandler
extends java.lang.Object
implements LobHandler

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. Developed and tested on Oracle 9i.

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) having different constant values! As it initializes the 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
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 org.apache.commons.logging.Log`	`logger`

Constructor Summary
`OracleLobHandler()` This constructor retrieves the oracle.sql.BLOB and oracle.sql.CLOB classes via reflection, and initializes the values for the DURATION_SESSION and MODE_READWRITE constants defined there.

Method Summary
`java.io.InputStream`	`getBlobAsBinaryStream(java.sql.ResultSet rs, int columnIndex)` Retrieve the given column as binary stream from the given ResultSet.
`byte[]`	`getBlobAsBytes(java.sql.ResultSet rs, int columnIndex)` Retrieve the given column as bytes from the given ResultSet.
`java.io.InputStream`	`getClobAsAsciiStream(java.sql.ResultSet rs, int columnIndex)` Retrieve the given column as ASCII stream from the given ResultSet.
`java.io.Reader`	`getClobAsCharacterStream(java.sql.ResultSet rs, int columnIndex)` Retrieve the given column as character stream from the given ResultSet.
`java.lang.String`	`getClobAsString(java.sql.ResultSet rs, int columnIndex)` Retrieve the given column as String from the given ResultSet.
`LobCreator`	`getLobCreator()` Create a new LobCreator instance, i.e. a session for creating BLOBs and CLOBs.
`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.

Methods inherited from class java.lang.Object

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

Field Detail

logger

protected final org.apache.commons.logging.Log logger

Constructor Detail

OracleLobHandler

public OracleLobHandler()
                 throws java.lang.ClassNotFoundException,
                        java.lang.NoSuchFieldException,
                        java.lang.IllegalAccessException

This constructor retrieves the oracle.sql.BLOB and oracle.sql.CLOB classes via reflection, and initializes the values for the DURATION_SESSION and MODE_READWRITE constants defined there.
See Also:: oracle.sql.BLOB#DURATION_SESSION, oracle.sql.BLOB#MODE_READWRITE, oracle.sql.CLOB#DURATION_SESSION, oracle.sql.CLOB#MODE_READWRITE

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 such pools need to return wrapped JDBC object handles.

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. So if PreparedStatement.getConnection() returns a native JDBC Connection with your pool, you don't need to specify an extractor.

See Also:: NativeJdbcExtractor.getNativeConnectionFromStatement(java.sql.Statement), 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