/*
Copyright (C) 2002 MySQL AB
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
package com.mysql.jdbc;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.sql.SQLException;
/**
* The representation (mapping) in the JavaTM programming language of an SQL
* BLOB value. An SQL BLOB is a built-in type that stores a Binary Large
* Object as a column value in a row of a database table. The driver
* implements Blob using an SQL locator(BLOB), which means that a Blob object
* contains a logical pointer to the SQL BLOB data rather than the data
* itself. A Blob object is valid for the duration of the transaction in
* which is was created. Methods in the interfaces ResultSet,
* CallableStatement, and PreparedStatement, such as getBlob and setBlob
* allow a programmer to access an SQL BLOB value. The Blob interface
* provides methods for getting the length of an SQL BLOB (Binary Large
* Object) value, for materializing a BLOB value on the client, and for
* determining the position of a pattern of bytes within a BLOB value. This
* class is new in the JDBC 2.0 API.
*
* @author Mark Matthews
*
* @version $Id: Blob.java,v 1.9.2.6 2003/12/24 05:16:26 mmatthew Exp $
*/
public class Blob implements java.sql.Blob, OutputStreamWatcher {
//~ Instance fields --------------------------------------------------------
/** The ResultSet that created this BLOB */
private ResultSet creatorResultSet;
//
// This is a real brain-dead implementation of BLOB. Once I add
// streamability to the I/O for MySQL this will be more efficiently
// implemented (except for the position() method, ugh).
//
/** The binary data that makes up this BLOB */
private byte[] binaryData = null;
/** The column that this BLOB came from */
private int columnIndex;
//~ Constructors -----------------------------------------------------------
/**
* Creates a BLOB encapsulating the given binary data
*/
Blob(byte[] data) {
setBinaryData(data);
this.creatorResultSet = null;
this.columnIndex = 0;
}
/**
* Creates an updatable BLOB that can update in-place
* (not implemented yet).
*/
Blob(byte[] data, ResultSet creatorResultSet, int columnIndex) {
setBinaryData(data);
this.creatorResultSet = creatorResultSet;
this.columnIndex = columnIndex;
}
//~ Methods ----------------------------------------------------------------
/**
* @see Blob#setBinaryStream(long)
*/
public OutputStream setBinaryStream(long indexToWriteAt)
throws SQLException {
if (indexToWriteAt < 1) {
throw new SQLException("indexToWriteAt must be >= 1", SQLError.SQL_STATE_ILLEGAL_ARGUMENT);
}
WatchableOutputStream bytesOut = new WatchableOutputStream();
bytesOut.setWatcher(this);
if (indexToWriteAt > 0) {
bytesOut.write(this.binaryData, 0, (int) (indexToWriteAt - 1));
}
return bytesOut;
}
/**
* Retrieves the BLOB designated by this Blob instance as a stream.
*
* @return this BLOB represented as a binary stream of bytes.
*
* @throws SQLException if a database error occurs
*/
public java.io.InputStream getBinaryStream() throws SQLException {
return new ByteArrayInputStream(getBinaryData());
}
/**
* @see Blob#setBytes(long, byte[], int, int)
*/
public int setBytes(long writeAt, byte[] bytes, int offset, int length)
throws SQLException {
OutputStream bytesOut = setBinaryStream(writeAt);
try {
bytesOut.write(bytes, offset, length);
} catch (IOException ioEx) {
throw new SQLException("IO Error while writing bytes to blob",
SQLError.SQL_STATE_GENERAL_ERROR);
} finally {
try {
bytesOut.close();
} catch (IOException doNothing) {
; // do nothing
}
}
return length;
}
/**
* @see Blob#setBytes(long, byte[])
*/
public int setBytes(long writeAt, byte[] bytes) throws SQLException {
return setBytes(writeAt, bytes, 0, bytes.length);
}
/**
* Returns as an array of bytes, part or all of the BLOB value that this
* Blob object designates.
*
* @param pos where to start the part of the BLOB
* @param length the length of the part of the BLOB you want returned.
*
* @return the bytes stored in the blob starting at position
* <code>pos</code> and having a length of <code>length</code>.
*
* @throws SQLException if a database error occurs
*/
public byte[] getBytes(long pos, int length) throws SQLException {
if (pos < 1) {
throw new SQLException("Position 'pos' can not be < 1", SQLError.SQL_STATE_ILLEGAL_ARGUMENT);
}
byte[] newData = new byte[length];
System.arraycopy(getBinaryData(), (int) (pos - 1), newData, 0, length);
return newData;
}
/**
* Returns the number of bytes in the BLOB value designated by this Blob
* object.
*
* @return the length of this blob
*
* @throws SQLException if a database error occurs
*/
public long length() throws SQLException {
return getBinaryData().length;
}
/**
* Finds the position of the given pattern in this BLOB.
*
* @param pattern the pattern to find
* @param start where to start finding the pattern
*
* @return the position where the pattern is found in the BLOB, -1 if not
* found
*
* @throws SQLException if a database error occurs
*/
public long position(java.sql.Blob pattern, long start)
throws SQLException {
return position(pattern.getBytes(0, (int) pattern.length()), start);
}
/**
* @see java.sql.Blob#position(byte[], long)
*/
public long position(byte[] pattern, long start) throws SQLException {
throw new SQLException("Not implemented");
}
/**
* @see com.mysql.jdbc.OutputStreamWatcher#streamClosed(byte[])
*/
public void streamClosed(byte[] byteData) {
this.binaryData = byteData;
}
/**
* @see Blob#truncate(long)
*/
public void truncate(long arg0) throws SQLException {
throw new NotImplemented();
}
private void setBinaryData(byte[] binaryData) {
this.binaryData = binaryData;
}
private byte[] getBinaryData() {
return binaryData;
}
}