bytesmessageimpl.java

来自「OpenJMS是一个开源的Java Message Service API 1.」· Java 代码 · 共 968 行 · 第 1/3 页

/**
 * Redistribution and use of this software and associated documentation
 * ("Software"), with or without modification, are permitted provided
 * that the following conditions are met:
 *
 * 1. Redistributions of source code must retain copyright
 *    statements and notices.  Redistributions must also contain a
 *    copy of this document.
 *
 * 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 name "Exolab" must not be used to endorse or promote
 *    products derived from this Software without prior written
 *    permission of Exoffice Technologies.  For written permission,
 *    please contact [e-mail].
 *
 * 4. Products derived from this Software may not be called "Exolab"
 *    nor may "Exolab" appear in their names without prior written
 *    permission of Exoffice Technologies. Exolab is a registered
 *    trademark of Exoffice Technologies.
 *
 * 5. Due credit should be given to the Exolab Project
 *    (http://www.exolab.org/).
 *
 * THIS SOFTWARE IS PROVIDED BY EXOFFICE TECHNOLOGIES AND CONTRIBUTORS
 * ``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
 * EXOFFICE TECHNOLOGIES OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND 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.
 *
 * Copyright 2000-2005 (C) Exoffice Technologies Inc. All Rights Reserved.
 *
 * $Id: BytesMessageImpl.java,v 1.2 2005/03/18 03:50:12 tanderson Exp $
 */
package org.exolab.jms.message;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.EOFException;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectOutput;
import java.io.UTFDataFormatException;

import javax.jms.BytesMessage;
import javax.jms.JMSException;
import javax.jms.MessageEOFException;
import javax.jms.MessageFormatException;
import javax.jms.MessageNotReadableException;
import javax.jms.MessageNotWriteableException;


/**
 * This class implements the {@link BytesMessage} interface.
 *
 * @version     $Revision: 1.2 $ $Date: 2005/03/18 03:50:12 $
 * @author      <a href="mailto:[e-mail]">Jim Mourikis</a>
 * @author      <a href="mailto:[e-mail]">Tim Anderson</a>
 * @see         BytesMessage
 */
public final class BytesMessageImpl extends MessageImpl
    implements BytesMessage {

    /**
     * Object version no. for serialization.
     */
    static final long serialVersionUID = 1;

    /**
     * Empty byte array for initialisation purposes.
     */
    private static final byte[] EMPTY = new byte[]{};

    /**
     * The byte stream to store data.
     */
    private byte[] _bytes = EMPTY;

    /**
     * The stream used for writes.
     */
    private DataOutputStream _out = null;

    /**
     * The byte stream backing the output stream.
     */
    private ByteArrayOutputStream _byteOut = null;

    /**
     * The stream used for reads.
     */
    private DataInputStream _in = null;

    /**
     * The byte stream backing the input stream.
     */
    private ByteArrayInputStream _byteIn = null;

    /**
     * The offset of the byte stream to start reading from. This defaults
     * to 0, and only applies to messages that are cloned from a
     * read-only instance where part of the stream had already been read.
     */
    private int _offset = 0;

    /**
     * Construct a new BytesMessage. When first created, the message is in
     * write-only mode.
     *
     * @throws JMSException if the message type can't be set
     */
    public BytesMessageImpl() throws JMSException {
        setJMSType("BytesMessage");
    }

    /**
     * Clone an instance of this object.
     *
     * @return a copy of this object
     * @throws CloneNotSupportedException if object or attributes aren't
     * cloneable
     */
    public final Object clone() throws CloneNotSupportedException {
        BytesMessageImpl result = (BytesMessageImpl) super.clone();
        if (_bodyReadOnly) {
            result._bytes = new byte[_bytes.length];
            System.arraycopy(_bytes, 0, result._bytes, 0, _bytes.length);
            if (_byteIn != null) {
                // if a client subsequently reads from the cloned object,
                // start reading from offset of the original stream
                _offset = _bytes.length - _byteIn.available();
            }
            result._byteIn = null;
            result._in = null;
        } else {
            if (_out != null) {
                try {
                    _out.flush();
                } catch (IOException exception) {
                    throw new CloneNotSupportedException(
                        exception.getMessage());
                }
                result._bytes = _byteOut.toByteArray();
                result._byteOut = null;
                result._out = null;
            } else {
                result._bytes = new byte[_bytes.length];
                System.arraycopy(_bytes, 0, result._bytes, 0, _bytes.length);
            }
        }

        return result;
    }

    /**
     * Serialize out this message's data.
     *
     * @param out the stream to serialize out to
     * @throws IOException if any I/O exceptions occurr
     */
    public final void writeExternal(ObjectOutput out) throws IOException {
        // If it was in write mode, extract the byte array.
        if (!_bodyReadOnly && _out != null) {
            _out.flush();
            _bytes = _byteOut.toByteArray();
        }

        super.writeExternal(out);
        out.writeLong(serialVersionUID);
        out.writeInt(_bytes.length);
        out.write(_bytes);
        out.flush();
    }

    /**
     * Serialize in this message's data.
     *
     * @param in the stream to serialize in from
     * @throws ClassNotFoundException if the class for an object being
     * restored cannot be found.
     * @throws IOException if any I/O exceptions occur
     */
    public final void readExternal(ObjectInput in)
        throws ClassNotFoundException, IOException {
        super.readExternal(in);
        long version = in.readLong();
        if (version == serialVersionUID) {
            int length = in.readInt();
            _bytes = new byte[length];
            in.readFully(_bytes);
        } else {
            throw new IOException("Incorrect version enountered: " + version +
                ". This version = " + serialVersionUID);
        }
    }

    /**
     * Gets the number of bytes of the message body when the message is in
     * read-only mode. The value returned can be used to allocate a byte array.
     * The value returned is the entire length of the message body, regardless
     * of where the pointer for reading the message is currently located.
     *
     * @return number of bytes in the message
     * @throws JMSException                if the JMS provider fails to read the
     *                                     message due to some internal error.
     * @throws MessageNotReadableException if the message is in write-only
     *                                     mode.
     */

    public long getBodyLength() throws JMSException {
        checkRead();
        return _bytes.length;
    }

    /**
     * Read a <code>boolean</code> from the bytes message stream.
     *
     * @return the <code>boolean</code> value read
     * @throws JMSException if JMS fails to read message due to some internal
     * JMS error
     * @throws MessageEOFException if end of bytes stream
     * @throws MessageNotReadableException if message is in write-only mode
     */
    public final boolean readBoolean() throws JMSException {
        boolean result = false;
        prepare();
        try {
            result = _in.readBoolean();
        } catch (IOException exception) {
            revert(exception);
        }
        return result;
    }

    /**
     * Read a signed 8-bit value from the bytes message stream.
     *
     * @return the next byte from the bytes message stream as a signed 8-bit
     * <code>byte</code>
     * @throws JMSException if JMS fails to read message due to some internal
     * JMS error
     * @throws MessageEOFException if end of message stream
     * @throws MessageNotReadableException if message is in write-only mode
     */
    public final byte readByte() throws JMSException {
        byte result = 0;
        prepare();
        try {
            result = _in.readByte();
        } catch (IOException exception) {
            revert(exception);
        }
        return result;
    }

    /**
     * Read an unsigned 8-bit number from the bytes message stream.
     *
     * @return the next byte from the bytes message stream, interpreted as an
     * unsigned 8-bit number
     * @throws JMSException if JMS fails to read message due to some internal
     * JMS error
     * @throws MessageNotReadableException if message is in write-only mode
     * @throws MessageEOFException if end of message stream
     */
    public final int readUnsignedByte() throws JMSException {
        int result = 0;
        prepare();
        try {
            result = _in.readUnsignedByte();
        } catch (IOException exception) {
            revert(exception);
        }
        return result;
    }

    /**
     * Read a signed 16-bit number from the bytes message stream.
     *
     * @return the next two bytes from the bytes message stream, interpreted
     * as a signed 16-bit number
     * @throws JMSException if JMS fails to read message due to some internal
     * JMS error
     * @throws MessageEOFException if end of message stream
     * @throws MessageNotReadableException if message is in write-only mode
     */
    public final short readShort() throws JMSException {
        short result = 0;
        prepare();
        try {
            result = _in.readShort();
        } catch (IOException exception) {
            revert(exception);
        }
        return result;
    }

    /**
     * Read an unsigned 16-bit number from the bytes message stream.
     *
     * @return the next two bytes from the bytes message stream, interpreted
     * as an unsigned 16-bit integer
     *
     * @throws JMSException if JMS fails to read message due to some internal
     * JMS error
     * @throws MessageEOFException if end of message stream
     * @throws MessageNotReadableException if message is in write-only mode
     */
    public final int readUnsignedShort() throws JMSException {
        int result = 0;
        prepare();