blobimpl.java

第三方的SQL Server and Sybase的jdbc dirver,速度更快

// jTDS JDBC Driver for Microsoft SQL Server and Sybase
// Copyright (C) 2004 The jTDS Project
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library 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
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
//
package net.sourceforge.jtds.jdbc;

import java.io.InputStream;
import java.io.OutputStream;
import java.sql.Blob;
import java.sql.SQLException;

import net.sourceforge.jtds.util.BlobBuffer;

/**
 * An in-memory or disk based representation of binary data.
 *
 * @author Brian Heineman
 * @author Mike Hutchinson
 * @version $Id: BlobImpl.java,v 1.30 2005/04/28 14:29:25 alin_sinpalean Exp $
 */
public class BlobImpl implements Blob {
    /**
     * 0 length <code>byte[]</code> as initial value for empty
     * <code>Blob</code>s.
     */
    private static final byte[] EMPTY_BLOB = new byte[0];

    /** The underlying <code>BlobBuffer</code>. */
    private final BlobBuffer blobBuffer;

    /**
     * Constructs a new empty <code>Blob</code> instance.
     *
     * @param connection a reference to the parent connection object
     */
    BlobImpl(ConnectionJDBC2 connection) {
        this(connection, EMPTY_BLOB);
    }

    /**
     * Constructs a new <code>Blob</code> instance initialized with data.
     *
     * @param connection a reference to the parent connection object
     * @param bytes      the blob object to encapsulate
     */
    BlobImpl(ConnectionJDBC2 connection, byte[] bytes) {
        if (bytes == null) {
            throw new IllegalArgumentException("bytes cannot be null");
        }

        blobBuffer = new BlobBuffer(connection.getLobBuffer());
        blobBuffer.setBuffer(bytes, false);
    }

    //
    // ------ java.sql.Blob interface methods from here -------
    //

    public InputStream getBinaryStream() throws SQLException {
        return blobBuffer.getBinaryStream(false);
    }

    public byte[] getBytes(long pos, int length) throws SQLException {
        return blobBuffer.getBytes(pos, length);
    }

    public long length() throws SQLException {
        return blobBuffer.getLength();
    }

    public long position(byte[] pattern, long start) throws SQLException {
        return blobBuffer.position(pattern, start);
    }

    public long position(Blob pattern, long start) throws SQLException {
        if (pattern == null) {
            throw new SQLException(Messages.get("error.blob.badpattern"), "HY009");
        }
        return blobBuffer.position(pattern.getBytes(1, (int) pattern.length()), start);
    }

    public OutputStream setBinaryStream(final long pos) throws SQLException {
        return blobBuffer.setBinaryStream(pos, false);
    }

    public int setBytes(long pos, byte[] bytes) throws SQLException {
        if (bytes == null) {
            throw new SQLException(Messages.get("error.blob.bytesnull"), "HY009");
        }
        return setBytes(pos, bytes, 0, bytes.length);
    }

    public int setBytes(long pos, byte[] bytes, int offset, int len)
            throws SQLException {
        if (bytes == null) {
            throw new SQLException(Messages.get("error.blob.bytesnull"), "HY009");
        }
        // Force BlobBuffer to take a copy of the byte array
        // In many cases this is wasteful but the user may
        // reuse the byte buffer corrupting the original set
        return blobBuffer.setBytes(pos, bytes, offset, len, true);
    }

    public void truncate(long len) throws SQLException {
        blobBuffer.truncate(len);
    }
}