/*-------------------------------------------------------------------------
*
* Copyright (c) 2005-2008, PostgreSQL Global Development Group
*
* IDENTIFICATION
* $PostgreSQL: pgjdbc/org/postgresql/jdbc2/AbstractJdbc2BlobClob.java,v 1.9 2008/01/08 06:56:28 jurka Exp $
*
*-------------------------------------------------------------------------
*/
package org.postgresql.jdbc2;
import java.io.InputStream;
import java.io.OutputStream;
import java.sql.Blob;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.Iterator;
import org.postgresql.core.BaseConnection;
import org.postgresql.largeobject.LargeObject;
import org.postgresql.largeobject.LargeObjectManager;
import org.postgresql.util.GT;
import org.postgresql.util.PSQLState;
import org.postgresql.util.PSQLException;
/**
* This class holds all of the methods common to both Blobs and Clobs.
*
* @author Michael Barker <mailto:mike@middlesoft.co.uk>
*
*/
public abstract class AbstractJdbc2BlobClob
{
protected BaseConnection conn;
protected LargeObject lo;
/**
* We create separate LargeObjects for methods that use streams
* so they won't interfere with each other.
*/
private ArrayList subLOs;
public AbstractJdbc2BlobClob(BaseConnection conn, long oid) throws SQLException
{
this.conn = conn;
LargeObjectManager lom = conn.getLargeObjectAPI();
this.lo = lom.open(oid);
subLOs = new ArrayList();
}
public synchronized void free() throws SQLException
{
if (lo != null) {
lo.close();
lo = null;
}
Iterator i = subLOs.iterator();
while (i.hasNext()) {
LargeObject subLO = (LargeObject)i.next();
subLO.close();
}
subLOs = null;
}
/**
* For Blobs this should be in bytes while for Clobs it should be
* in characters. Since we really haven't figured out how to handle
* character sets for Clobs the current implementation uses bytes for
* both Blobs and Clobs.
*/
public synchronized void truncate(long len) throws SQLException
{
checkFreed();
if (!conn.haveMinimumServerVersion("8.3"))
throw new PSQLException(GT.tr("Truncation of large objects is only implemented in 8.3 and later servers."), PSQLState.NOT_IMPLEMENTED);
assertPosition(len);
lo.truncate((int)len);
}
public synchronized long length() throws SQLException
{
checkFreed();
return lo.size();
}
public synchronized byte[] getBytes(long pos, int length) throws SQLException
{
assertPosition(pos);
lo.seek((int)(pos-1), LargeObject.SEEK_SET);
return lo.read(length);
}
public synchronized InputStream getBinaryStream() throws SQLException
{
checkFreed();
LargeObject subLO = lo.copy();
subLOs.add(subLO);
subLO.seek(0, LargeObject.SEEK_SET);
return subLO.getInputStream();
}
public synchronized OutputStream setBinaryStream(long pos) throws SQLException
{
assertPosition(pos);
LargeObject subLO = lo.copy();
subLOs.add(subLO);
subLO.seek((int)(pos-1));
return subLO.getOutputStream();
}
/**
* Iterate over the buffer looking for the specified pattern
*
* @param pattern A pattern of bytes to search the blob for.
* @param start The position to start reading from.
*/
public synchronized long position(byte[] pattern, long start) throws SQLException
{
assertPosition(start, pattern.length);
int position = 1;
int patternIdx = 0;
long result = -1;
int tmpPosition = 1;
for (LOIterator i = new LOIterator(start-1); i.hasNext(); position++)
{
byte b = i.next();
if (b == pattern[patternIdx])
{
if (patternIdx == 0)
{
tmpPosition = position;
}
patternIdx++;
if (patternIdx == pattern.length)
{
result = tmpPosition;
break;
}
}
else
{
patternIdx = 0;
}
}
return result;
}
/**
* Iterates over a large object returning byte values. Will buffer
* the data from the large object.
*
*
*/
private class LOIterator
{
private static final int BUFFER_SIZE = 8096;
private byte buffer[] = new byte[BUFFER_SIZE];
private int idx = BUFFER_SIZE;
private int numBytes = BUFFER_SIZE;
public LOIterator(long start) throws SQLException
{
lo.seek((int) start);
}
public boolean hasNext() throws SQLException
{
boolean result = false;
if (idx < numBytes)
{
result = true;
}
else
{
numBytes = lo.read(buffer, 0, BUFFER_SIZE);
idx = 0;
result = (numBytes > 0);
}
return result;
}
private byte next()
{
return buffer[idx++];
}
}
/**
* This is simply passing the byte value of the pattern Blob
*/
public synchronized long position(Blob pattern, long start) throws SQLException
{
return position(pattern.getBytes(1, (int)pattern.length()), start);
}
/**
* Throws an exception if the pos value exceeds the max value by
* which the large object API can index.
*
* @param pos Position to write at.
*/
protected void assertPosition(long pos) throws SQLException
{
assertPosition(pos, 0);
}
/**
* Throws an exception if the pos value exceeds the max value by
* which the large object API can index.
*
* @param pos Position to write at.
* @param len number of bytes to write.
*/
protected void assertPosition(long pos, long len) throws SQLException
{
checkFreed();
if (pos < 1)
{
throw new PSQLException(GT.tr("LOB positioning offsets start at 1."), PSQLState.INVALID_PARAMETER_VALUE);
}
if (pos + len - 1 > Integer.MAX_VALUE)
{
throw new PSQLException(GT.tr("PostgreSQL LOBs can only index to: {0}", new Integer(Integer.MAX_VALUE)), PSQLState.INVALID_PARAMETER_VALUE);
}
}
/**
* Checks that this LOB hasn't been free()d already.
* @throws SQLException if LOB has been freed.
*/
protected void checkFreed() throws SQLException
{
if (lo == null)
throw new PSQLException(GT.tr("free() was called on this LOB previously"), PSQLState.OBJECT_NOT_IN_STATE);
}
}