OracleLobHandler (Spring Framework API 2.1) - Spring Framework 2.1.0 API 文档英文版

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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
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) 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
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. a session for creating BLOBs and CLOBs.

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 and MODE_READWRITE constants defined there.

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 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

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. a session for creating BLOBs and CLOBs.
`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 and MODE_READWRITE constants defined there.
`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 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

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 and MODE_READWRITE 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.CLOB#DURATION_SESSION, oracle.sql.CLOB#MODE_READWRITE