FastByteArrayOutputStream.java

/**
 * See the NOTICE file distributed with this work for additional
 * information regarding copyright ownership.
 *
 * This 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 software 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 software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */
package org.ut.biolab.medsavant.shared.util;

import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.ByteArrayInputStream;

/**
 * ByteArrayOutputStream implementation that doesn't synchronize methods
 * and doesn't copy the data on toByteArray().
 */
public class FastByteArrayOutputStream extends OutputStream {
    /**
     * Buffer and size
     */
    protected byte[] buf = null;
    protected int size = 0;

    /**
     * Constructs a stream with buffer capacity size 5K
     */
    public FastByteArrayOutputStream() {
        this(5 * 1024);
    }

    /**
     * Constructs a stream with the given initial size
     */
    public FastByteArrayOutputStream(int initSize) {
        this.size = 0;
        this.buf = new byte[initSize];
    }

    /**
     * Ensures that we have a large enough buffer for the given size.
     */
    private void verifyBufferSize(int sz) {
        if (sz > buf.length) {
            byte[] old = buf;
            buf = new byte[Math.max(sz, 2 * buf.length )];
            System.arraycopy(old, 0, buf, 0, old.length);
            old = null;
        }
    }

    public int getSize() {
        return size;
    }

    /**
     * Returns the byte array containing the written data. Note that this
     * array will almost always be larger than the amount of data actually
     * written.
     */
    public byte[] getByteArray() {
        return buf;
    }

    public final void write(byte b[]) {
        verifyBufferSize(size + b.length);
        System.arraycopy(b, 0, buf, size, b.length);
        size += b.length;
    }

    public final void write(byte b[], int off, int len) {
        verifyBufferSize(size + len);
        System.arraycopy(b, off, buf, size, len);
        size += len;
    }

    public final void write(int b) {
        verifyBufferSize(size + 1);
        buf[size++] = (byte) b;
    }

    public void reset() {
        size = 0;
    }

    /**
     * Returns a ByteArrayInputStream for reading back the written data
     */
    public InputStream getInputStream() {
        return new FastByteArrayInputStream(buf, size);
    }

}