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

        try {
            getOutputStream().writeLong(value);
        } catch (IOException exception) {
            raise(exception);
        }
    }

    /**
     * Convert the float argument to an <code>int</code> using the
     * <code>floatToIntBits</code> method in class <code>Float</code>,
     * and then writes that <code>int</code> value to the bytes message
     * stream as a 4-byte quantity, high byte first.
     *
     * @param value the <code>float</code> value to be written.
     * @throws JMSException if JMS fails to write message due to some internal
     * JMS error
     * @throws MessageNotWriteableException if message is in read-only mode
     */
    public final void writeFloat(float value) throws JMSException {
        checkWrite();
        try {
            getOutputStream().writeFloat(value);
        } catch (IOException exception) {
            raise(exception);
        }
    }


    /**
     * Convert the double argument to a <code>long</code> using the
     * <code>doubleToLongBits</code> method in class <code>Double</code>,
     * and then writes that <code>long</code> value to the bytes message
     * stream as an 8-byte quantity, high byte first.
     *
     * @param value the <code>double</code> value to be written.
     * @throws JMSException if JMS fails to write message due to some internal
     * JMS error
     * @throws MessageNotWriteableException if message is in read-only mode
     */
    public final void writeDouble(double value) throws JMSException {
        checkWrite();
        try {
            getOutputStream().writeDouble(value);
        } catch (IOException exception) {
            raise(exception);
        }
    }

    /**
     * Write a string to the bytes message stream using UTF-8 encoding in a
     * machine-independent manner.
     *
     * <p>For more information on the UTF-8 format, see "File System Safe
     * UCS Transformation Format (FSS_UFT)", X/Open Preliminary Specification,
     * X/Open Company Ltd., Document Number: P316. This information also
     * appears in ISO/IEC 10646, Annex P.
     *
     * @param value the <code>String</code> value to be written
     * @throws MessageNotWriteableException if message is in read-only mode
     * @throws JMSException if JMS fails to write message due to some internal
     * JMS error
     */
    public final void writeUTF(String value) throws JMSException {
        checkWrite();
        try {
            getOutputStream().writeUTF(value);
        } catch (IOException exception) {
            raise(exception);
        }
    }

    /**
     * Write a byte array to the bytes message stream.
     *
     * @param value the byte array to be written.
     * @throws JMSException if JMS fails to write message due to some internal
     * JMS error
     * @throws MessageNotWriteableException if message is in read-only mode
     */
    public final void writeBytes(byte[] value) throws JMSException {
        checkWrite();
        try {
            getOutputStream().write(value);
        } catch (IOException exception) {
            raise(exception);
        }
    }

    /**
     * Write a portion of a byte array to the bytes message stream
     *
     * @param value the byte array value to be written.
     * @param offset the initial offset within the byte array.
     * @param length the number of bytes to use.
     * @throws JMSException if JMS fails to write message due to some internal
     * JMS error
     * @throws MessageNotWriteableException if message is in read-only mode
     */
    public final void writeBytes(byte[] value, int offset, int length)
        throws JMSException {
        checkWrite();
        try {
            getOutputStream().write(value, offset, length);
        } catch (IOException exception) {
            raise(exception);
        }
    }

    /**
     * Write a Java object to the bytes message stream.
     *
     * <p>Note that this method only works for the objectified primitive
     * object types (Integer, Double, Long ...), String's and byte arrays.
     *
     * @param value the Java object to be written. Must not be null.
     *
     * @throws JMSException if JMS fails to write message due to some internal
     * JMS error
     * @throws MessageFormatException if object is invalid type
     * @throws MessageNotWriteableException if message in read-only mode
     * @throws NullPointerException if parameter <code>value</code> is null
     */
    public final void writeObject(Object value) throws JMSException {
        if (value instanceof Boolean) {
            writeBoolean(((Boolean) value).booleanValue());
        } else if (value instanceof Byte) {
            writeByte(((Byte) value).byteValue());
        } else if (value instanceof Short) {
            writeShort(((Short) value).shortValue());
        } else if (value instanceof Character) {
            writeChar(((Character) value).charValue());
        } else if (value instanceof Integer) {
            writeInt(((Integer) value).intValue());
        } else if (value instanceof Long) {
            writeLong(((Long) value).longValue());
        } else if (value instanceof Float) {
            writeFloat(((Float) value).floatValue());
        } else if (value instanceof Double) {
            writeDouble(((Double) value).doubleValue());
        } else if (value instanceof String) {
            writeUTF((String) value);
        } else if (value instanceof byte[]) {
            writeBytes((byte[]) value);
        } else if (value == null) {
            throw new NullPointerException(
                "BytesMessage does not support null");
        } else {
            throw new MessageFormatException("Cannot write objects of type=" +
                value.getClass().getName());
        }
    }

    /**
     * Put the message body in read-only mode, and reposition the stream of
     * bytes to the beginning.
     *
     * @throws JMSException if JMS fails to reset the message due to some
     * internal JMS error
     */
    public final void reset() throws JMSException {
        try {
            if (!_bodyReadOnly) {
                _bodyReadOnly = true;
                if (_out != null) {
                    _out.flush();
                    _bytes = _byteOut.toByteArray();
                    _byteOut = null;
                    _out.close();
                    _out = null;
                }
            } else {
                if (_in != null) {
                    _byteIn = null;
                    _in.close();
                    _in = null;
                }
            }
        } catch (IOException exception) {
            raise(exception);
        }
    }

    /**
     * Overide the super class method to reset the streams, and put the
     * message body in write only mode.
     *
     * <p>If <code>clearBody</code> is called on a message in read-only mode,
     * the message body is cleared and the message is in write-only mode.
     * bytes to the beginning.
     *
     *	<p>If <code>clearBody</code> is called on a message already in
     * 	write-only mode, the spec does not define the outcome, so do nothing.
     * 	Client must then call <code>reset</code>, followed by
     *	<code>clearBody</code> to reset the stream at the beginning for a
     *	new write.
     * @throws JMSException if JMS fails to reset the message due to some
     * internal JMS error
     */
    public final void clearBody() throws JMSException {
        try {
            if (_bodyReadOnly) {
                // in read-only mode
                _bodyReadOnly = false;
                if (_in != null) {
                    _byteIn = null;
                    _in.close();
                    _in = null;
                    _offset = 0;
                }
            } else if (_out != null) {
                // already in write-only mode
                _byteOut = null;
                _out.close();
                _out = null;
            }
            _bytes = EMPTY;
            _byteOut = null;
            _out = null;
        } catch (IOException exception) {
            raise(exception);
        }
    }

    /**
     * Set the read-only mode of the message.
     *
     * @param readOnly if true, make the message body and properties read-only,
     * and invoke {@link #reset}
     * @throws JMSException if the read-only mode cannot be changed
     */
    public final void setReadOnly(boolean readOnly) throws JMSException {
        if (readOnly) {
            reset();
        }
        super.setReadOnly(readOnly);
    }

    /**
     * Prepare to do a read.
     *
     * @throws JMSException if the current position in the stream can't be
     * marked
     * @throws MessageNotReadableException if the message is in write-only mode
     */
    private final void prepare() throws JMSException {
        checkRead();
        getInputStream();
        try {
            _in.mark(_bytes.length - _in.available());
        } catch (IOException exception) {
            raise(exception);
        }
    }

    /**
     * Reverts the stream to its prior position if an I/O exception is
     * thrown, and propagates the exception as a JMSException.
     *
     * @param exception the exception that caused the reset
     * @throws JMSException for general IOException errors
     * @throws MessageEOFException if end-of-file was reached
     */
    private final void revert(IOException exception) throws JMSException {
        try {
            _in.reset();
        } catch (IOException ignore) {
        }
        JMSException error = null;
        if (exception instanceof EOFException) {
            error = new MessageEOFException(exception.getMessage());
        } else if (exception instanceof UTFDataFormatException) {
            error = new MessageFormatException(exception.getMessage());
        } else {
            error = new JMSException(exception.getMessage());
        }
        error.setLinkedException(exception);
        throw error;
    }

    /**
     * Initialise the input stream if it hasn't been intialised.
     *
     * @return the input stream
     */
    private DataInputStream getInputStream() {
        if (_in == null) {
            _byteIn = new ByteArrayInputStream(_bytes, _offset,
                _bytes.length - _offset);
            _in = new DataInputStream(_byteIn);
        }
        return _in;
    }

    /**
     * Initialise the output stream if it hasn't been intialised.
     *
     * @return the output stream
     * @throws IOException if the output stream can't be created
     */
    private final DataOutputStream getOutputStream() throws IOException {
        if (_out == null) {
            _byteOut = new ByteArrayOutputStream();
            _out = new DataOutputStream(_byteOut);
            _out.write(_bytes);
        }
        return _out;
    }

    /**
     * Helper to raise a JMSException when an I/O error occurs.
     *
     * @param exception the exception that caused the failure
     * @throws JMSException
     */
    private final void raise(IOException exception) throws JMSException {
        JMSException error = new JMSException(exception.getMessage());
        error.setLinkedException(exception);
        throw error;
    }

}