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/*-------------------------------------------------------------------------
*
* Copyright (c) 2003-2011, PostgreSQL Global Development Group
*
*
*-------------------------------------------------------------------------
*/
package com.foundationdb.sql.jdbc.largeobject;

import java.io.InputStream;
import java.io.IOException;
import java.sql.SQLException;

/**
 *     This is an implementation of an InputStream from a large object.
 */
public class BlobInputStream extends InputStream
{
    /**
     * The parent LargeObject
     */
    private LargeObject lo;

    /**
     * Buffer used to improve performance
     */
    private byte[] buffer;

    /**
     * Position within buffer
     */
    private int bpos;

    /**
     * The buffer size
     */
    private int bsize;

    /**
     * The mark position
     */
    private int mpos = 0;

    /**
     * @param lo LargeObject to read from
     */
    public BlobInputStream(LargeObject lo)
    {
        this(lo, 1024);
    }

    /**
     * @param lo LargeObject to read from
     * @param bsize buffer size
     */
    public BlobInputStream(LargeObject lo, int bsize)
    {
        this.lo = lo;
        buffer = null;
        bpos = 0;
        this.bsize = bsize;
    }

    /**
     * The minimum required to implement input stream
     */
    public int read() throws java.io.IOException
    {
        checkClosed();
        try
        {
            if (buffer == null || bpos >= buffer.length)
            {
                buffer = lo.read(bsize);
                bpos = 0;
            }

            // Handle EOF
            if (bpos >= buffer.length)
            {
                return -1;
            }

            int ret = (buffer[bpos] & 0x7F);
            if ((buffer[bpos] &0x80) == 0x80)
            {
                ret |= 0x80;
            }

            bpos++;

            return ret;
        }
        catch (SQLException se)
        {
            throw new IOException(se.toString());
        }
    }


    /**
     * Closes this input stream and releases any system resources associated
     * with the stream.
     *
     * 

The close method of InputStream does * nothing. * * @exception IOException if an I/O error occurs. */ public void close() throws IOException { if (lo != null) { try { lo.close(); lo = null; } catch (SQLException se) { throw new IOException(se.toString()); } } } /** * Marks the current position in this input stream. A subsequent call to * the reset method repositions this stream at the last marked * position so that subsequent reads re-read the same bytes. * *

The readlimit arguments tells this input stream to * allow that many bytes to be read before the mark position gets * invalidated. * *

The general contract of mark is that, if the method * markSupported returns true, the stream somehow * remembers all the bytes read after the call to mark and * stands ready to supply those same bytes again if and whenever the method * reset is called. However, the stream is not required to * remember any data at all if more than readlimit bytes are * read from the stream before reset is called. * *

Marking a closed stream should not have any effect on the stream. * * @param readlimit the maximum limit of bytes that can be read before * the mark position becomes invalid. * @see java.io.InputStream#reset() */ public synchronized void mark(int readlimit) { try { mpos = lo.tell(); } catch (SQLException se) { // Can't throw this because mark API doesn't allow it. // throw new IOException(se.toString()); } } /** * Repositions this stream to the position at the time the * mark method was last called on this input stream. * NB: If mark is not called we move to the begining. * @see java.io.InputStream#mark(int) * @see java.io.IOException */ public synchronized void reset() throws IOException { checkClosed(); try { lo.seek(mpos); } catch (SQLException se) { throw new IOException(se.toString()); } } /** * Tests if this input stream supports the mark and * reset methods. The markSupported method of * InputStream returns false. * * @return true if this true type supports the mark and reset * method; false otherwise. * @see java.io.InputStream#mark(int) * @see java.io.InputStream#reset() */ public boolean markSupported() { return true; } private void checkClosed() throws IOException { if (lo == null) throw new IOException("BlobOutputStream is closed"); } }





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