bytefield.java

Office格式转换代码

/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2003 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Apache" and "Apache Software Foundation" and
 *    "Apache POI" must not be used to endorse or promote products
 *    derived from this software without prior written permission. For
 *    written permission, please contact [e-mail].
 *
 * 5. Products derived from this software may not be called "Apache",
 *    "Apache POI", nor may "Apache" appear in their name, without
 *    prior written permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */

package org.apache.poi.util;

import org.apache.poi.util.LittleEndian.BufferUnderrunException;

import java.io.*;

/**
 * representation of a byte (8-bit) field at a fixed location within a
 * byte array
 *
 * @author Marc Johnson (mjohnson at apache dot org
 */

public class ByteField
    implements FixedField
{
    private static final byte _default_value = 0;
    private byte              _value;
    private final int         _offset;

    /**
     * construct the ByteField with its offset into its containing
     * byte array and a default value of 0
     *
     * @param offset of the field within its byte array
     *
     * @exception ArrayIndexOutOfBoundsException if offset is negative
     */

    public ByteField(final int offset)
        throws ArrayIndexOutOfBoundsException
    {
        this(offset, _default_value);
    }

    /**
     * construct the ByteField with its offset into its containing
     * byte array and initialize its value
     *
     * @param offset of the field within its byte array
     * @param value the initial value
     *
     * @exception ArrayIndexOutOfBoundsException if offset is negative
     */

    public ByteField(final int offset, final byte value)
        throws ArrayIndexOutOfBoundsException
    {
        if (offset < 0)
        {
            throw new ArrayIndexOutOfBoundsException(
                "offset cannot be negative");
        }
        _offset = offset;
        set(value);
    }

    /**
     * Construct the ByteField with its offset into its containing
     * byte array and initialize its value from its byte array
     *
     * @param offset of the field within its byte array
     * @param data the byte array to read the value from
     *
     * @exception ArrayIndexOutOfBoundsException if the offset is not
     *            within the range of 0..(data.length - 1)
     */

    public ByteField(final int offset, final byte [] data)
        throws ArrayIndexOutOfBoundsException
    {
        this(offset);
        readFromBytes(data);
    }

    /**
     * construct the ByteField with its offset into its containing
     * byte array, initialize its value, and write its value to its
     * byte array
     *
     * @param offset of the field within its byte array
     * @param value the initial value
     * @param data the byte array to write the value to
     *
     * @exception ArrayIndexOutOfBoundsException if the offset is not
     *            within the range of 0..(data.length - 1)
     */

    public ByteField(final int offset, final byte value, final byte [] data)
        throws ArrayIndexOutOfBoundsException
    {
        this(offset, value);
        writeToBytes(data);
    }

    /**
     * get the ByteField's current value
     *
     * @return current value
     */

    public byte get()
    {
        return _value;
    }

    /**
     * set the ByteField's current value
     *
     * @param value to be set
     */

    public void set(final byte value)
    {
        _value = value;
    }

    /**
     * set the ByteField's current value and write it to a byte array
     *
     * @param value to be set
     * @param data the byte array to write the value to
     *
     * @exception ArrayIndexOutOfBoundsException if the offset is out
     *            of the byte array's range
     */

    public void set(final byte value, final byte [] data)
        throws ArrayIndexOutOfBoundsException
    {
        set(value);
        writeToBytes(data);
    }

    /* ********** START implementation of FixedField ********** */

    /**
     * set the value from its offset into an array of bytes
     *
     * @param data the byte array from which the value is to be read
     *
     * @exception ArrayIndexOutOfBoundsException if the offset is out
     *            of range of the bte array
     */

    public void readFromBytes(final byte [] data)
        throws ArrayIndexOutOfBoundsException
    {
        _value = data[ _offset ];
    }

    /**
     * set the value from an InputStream
     *
     * @param stream the InputStream from which the value is to be
     *               read
     *
     * @exception BufferUnderrunException if there is not enough data
     *            available from the InputStream
     * @exception IOException if an IOException is thrown from reading
     *            the InputStream
     */

    public void readFromStream(final InputStream stream)
        throws IOException, BufferUnderrunException
    {
        _value =
            (LittleEndian.readFromStream(stream,
                                         LittleEndianConsts.BYTE_SIZE))[ 0 ];
    }

    /**
     * write the value out to an array of bytes at the appropriate
     * offset
     *
     * @param data the array of bytes to which the value is to be
     *             written
     *
     * @exception ArrayIndexOutOfBoundsException if the offset is out
     *            of the byte array's range
     */

    public void writeToBytes(final byte [] data)
        throws ArrayIndexOutOfBoundsException
    {
        data[ _offset ] = _value;
    }

    /**
     * return the value as a String
     *
     * @return the value as a String
     */

    public String toString()
    {
        return String.valueOf(_value);
    }

    /* **********  END  implementation of FixedField ********** */
}   // end public class ByteField