org.afcs.warts.handlers
Class OracleBlobHandler

java.lang.Object
  org.afcs.warts.handlers.DataHandlerSupport
      org.afcs.warts.handlers.LobDataHandlerSupport
          org.afcs.warts.handlers.OracleBlobHandler

All Implemented Interfaces:

DataHandler

public final class OracleBlobHandler

extends LobDataHandlerSupport

implements DataHandler

The OracleBlobHandler class extends LobDataHandlerSupport and handles the reading and writing of BLOB data. The compilation and use of this code requires the availability of Oracle's proprietary JDBC drivers -- as of release 9.2.0.3 of their drivers, there is no way to write to BLOB columns without resorting to their non-standard API.

The object returned by loadValue(java.sql.ResultSet, int), and expected by bindValue() and printValue() is a stored in BinaryDataHolder instance.

LICENSE: This code is released to the public domain and may be used for any purpose whatsoever without permission or acknowledgment.

Version:

Last Modified 20 August 2003

Author:

Warren Hedley ( whedley at sdsc dot edu )

Constructor Summary

OracleBlobHandler(TableDescription tableDescription, ColumnDescription columnDescription)
Contructs a new instance for the specified table and column.

Method Summary

void	bindNonNullValue(java.sql.PreparedStatement statement, int variableIndex, java.lang.Object value) This method binds the specified non-null value (which should be a java.sql.Timestamp instance) to the specified index in the specified statement.
int	getNullType() Oracle returns the constant java.sql.Types.OTHER for BLOB columns, and bizarrely, this can not be used when binding null values in prepared statements.
java.lang.Object	loadValue(java.sql.ResultSet resultSet, int columnIndex) Returns a BinaryDataHolder instance with the bytes loaded from the specified column from the specified result set, if non-null.
java.lang.String	printNonNullValue(java.lang.Object value) Returns a representation of the specified value (which should be a BinaryDataHolder instance) that is appropriate for inclusion in a SQL script.
protected void	writeLobValue(java.sql.ResultSet results, java.lang.Object newLobValue) This method is responsible for writing the specified LOB value (which should be a BinaryDataHolder) to the first column in the specified result set, which should contain a newly initialized BLOB locator.

Methods inherited from class org.afcs.warts.handlers.LobDataHandlerSupport

postProcessBind, requiresBindPostProcessing, requiresStreamedLoading

Methods inherited from class org.afcs.warts.handlers.DataHandlerSupport

getColumnDescription, getTableDescription, isCharacterData, isNullHandler, loadBytesFromStream, logWrongValueTypeWarning, toString, verifyObjectIsString

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.afcs.warts.handlers.DataHandler

isCharacterData, isNullHandler, postProcessBind, requiresBindPostProcessing, requiresStreamedLoading

Constructor Detail

OracleBlobHandler

public OracleBlobHandler(TableDescription tableDescription,
                         ColumnDescription columnDescription)

Contructs a new instance for the specified table and column. The full table description is needed so that SQL statements can be generated for writing CLOB data.

Parameters:

tableDescription - The table that the handler will be handling data for.

columnDescription - The column that this class will be processing data for.

Method Detail

bindNonNullValue

public void bindNonNullValue(java.sql.PreparedStatement statement,
                             int variableIndex,
                             java.lang.Object value)
                      throws java.sql.SQLException

This method binds the specified non-null value (which should be a java.sql.Timestamp instance) to the specified index in the specified statement. A warning message is logged if the value is not a Timestamp.

Specified by:

bindNonNullValue in interface DataHandler

Parameters:

statement - The statement to bind the value in.

variableIndex - The index of the variable to bind.

value - The value to bind to the statement.

Throws:

java.sql.SQLException - If a SQL error occurs during binding.

getNullType

public int getNullType()

Oracle returns the constant java.sql.Types.OTHER for BLOB columns, and bizarrely, this can not be used when binding null values in prepared statements. This method overrides the default behaviour always returning java.sql.Types.BLOB. See my post to Oracle's JDBC forum for more information.

Specified by:

getNullType in interface DataHandler

Overrides:

getNullType in class DataHandlerSupport

Returns:

Always java.sql.Types.BLOB.

loadValue

public java.lang.Object loadValue(java.sql.ResultSet resultSet,
                                  int columnIndex)
                           throws java.sql.SQLException

Returns a BinaryDataHolder instance with the bytes loaded from the specified column from the specified result set, if non-null.

Specified by:

loadValue in interface DataHandler

Parameters:

resultSet - The result set to load data from.

columnIndex - The index of the column to load data from.

Returns:

A BinaryDataHolder object or null.

Throws:

java.sql.SQLException - If a SQL exception occurs while loading data.

printNonNullValue

public java.lang.String printNonNullValue(java.lang.Object value)

Returns a representation of the specified value (which should be a BinaryDataHolder instance) that is appropriate for inclusion in a SQL script.

Specified by:

printNonNullValue in interface DataHandler

Parameters:

value - The object value to print.

Returns:

A string containing a representation of the specified value appropriate for use in a SQL script.

writeLobValue

protected void writeLobValue(java.sql.ResultSet results,
                             java.lang.Object newLobValue)
                      throws java.sql.SQLException

This method is responsible for writing the specified LOB value (which should be a BinaryDataHolder) to the first column in the specified result set, which should contain a newly initialized BLOB locator.

Specified by:

writeLobValue in class LobDataHandlerSupport

Parameters:

results - The result set containing the BLOB locator.

newLobValue - The new LOB value.

Throws:

java.sql.SQLException - If a SQL error occurs during update.