Package org.apache.activemq.command

Class ActiveMQStreamMessage

  • All Implemented Interfaces:
    Message, StreamMessage, MessageReference, Command, DataStructure, MarshallAware, Message, ScheduledMessage
    public class ActiveMQStreamMessage
extends ActiveMQMessage
implements StreamMessage
    A StreamMessage object is used to send a stream of primitive types in the Java programming language. It is filled and read sequentially. It inherits from the Message interface and adds a stream message body. Its methods are based largely on those found in java.io.DataInputStream and java.io.DataOutputStream.

    The primitive types can be read or written explicitly using methods for each type. They may also be read or written generically as objects. For instance, a call to StreamMessage.writeInt(6) is equivalent to StreamMessage.writeObject(new Integer(6)). Both forms are provided, because the explicit form is convenient for static programming, and the object form is needed when types are not known at compile time.

    When the message is first created, and when clearBody is called, the body of the message is in write-only mode. After the first call to reset has been made, the message body is in read-only mode. After a message has been sent, the client that sent it can retain and modify it without affecting the message that has been sent. The same message object can be sent multiple times. When a message has been received, the provider has called reset so that the message body is in read-only mode for the client.

    If clearBody is called on a message in read-only mode, the message body is cleared and the message body is in write-only mode.

    If a client attempts to read a message in write-only mode, a MessageNotReadableException is thrown.

    If a client attempts to write a message in read-only mode, a MessageNotWriteableException is thrown.

    StreamMessage objects support the following conversion table. The marked cases must be supported. The unmarked cases must throw a JMSException. The String-to-primitive conversions may throw a runtime exception if the primitive's valueOf() method does not accept it as a valid String representation of the primitive.

    A value written as the row type can be read as the column type. 

      | | boolean byte short char int long float double String byte[]
 |----------------------------------------------------------------------
 |boolean | X X |byte | X X X X X |short | X X X X |char | X X |int | X X X
 |long | X X |float | X X X |double | X X |String | X X X X X X X X |byte[] |
 X |----------------------------------------------------------------------

    Attempting to read a null value as a primitive type must be treated as calling the primitive's corresponding valueOf(String) conversion method with a null value. Since char does not support a String conversion, attempting to read a null value as a char must throw a NullPointerException.

    See Also:
    Session.createStreamMessage(), BytesMessage, MapMessage, Message, ObjectMessage, TextMessage

    • Constructor Detail

      • ActiveMQStreamMessage

        public ActiveMQStreamMessage()

    • Method Detail

      • getJMSXMimeType

        public String getJMSXMimeType()
        Description copied from interface: Message
        Returns the MIME type of this mesage. This can be used in selectors to filter on the MIME types of the different JMS messages, or in the case of BlobMessage it allows you to create a selector on the MIME type of the BLOB body
        Specified by:
        getJMSXMimeType in interface Message
        Overrides:
        getJMSXMimeType in class ActiveMQMessage

      • clearBody

        public void clearBody()
               throws JMSException
        Clears out the message body. Clearing a message's body does not clear its header values or property entries.

        If this message body was read-only, calling this method leaves the message body in the same state as an empty body in a newly created message.

        Specified by:
        clearBody in interface Message
        Overrides:
        clearBody in class ActiveMQMessage
        Throws:
        JMSException - if the JMS provider fails to clear the message body due to some internal error.

      • readBytes

        public int readBytes​(byte[] value)
              throws JMSException
        Reads a byte array field from the stream message into the specified byte[] object (the read buffer).

        To read the field value, readBytes should be successively called until it returns a value less than the length of the read buffer. The value of the bytes in the buffer following the last byte read is undefined.

        If readBytes returns a value equal to the length of the buffer, a subsequent readBytes call must be made. If there are no more bytes to be read, this call returns -1.

        If the byte array field value is null, readBytes returns -1.

        If the byte array field value is empty, readBytes returns 0.

        Once the first readBytes call on a byte[] field value has been made, the full value of the field must be read before it is valid to read the next field. An attempt to read the next field before that has been done will throw a MessageFormatException.

        To read the byte field value into a new byte[] object, use the readObject method.

        Specified by:
        readBytes in interface StreamMessage
        Parameters:
        value - the buffer into which the data is read
        Returns:
        the total number of bytes read into the buffer, or -1 if there is no more data because the end of the byte field has been reached
        Throws:
        JMSException - if the JMS provider fails to read the message due to some internal error.
        MessageEOFException - if unexpected end of message stream has been reached.
        MessageFormatException - if this type conversion is invalid.
        MessageNotReadableException - if the message is in write-only mode.
        See Also:
        readObject()

      • readObject

        public Object readObject()
                  throws JMSException
        Reads an object from the stream message.

        This method can be used to return, in objectified format, an object in the Java programming language ("Java object") that has been written to the stream with the equivalent writeObject method call, or its equivalent primitive writetype method.

        Note that byte values are returned as byte[], not Byte[].

        An attempt to call readObject to read a byte field value into a new byte[] object before the full value of the byte field has been read will throw a MessageFormatException.

        Specified by:
        readObject in interface StreamMessage
        Returns:
        a Java object from the stream message, in objectified format (for example, if the object was written as an int, an Integer is returned)
        Throws:
        JMSException - if the JMS provider fails to read the message due to some internal error.
        MessageEOFException - if unexpected end of message stream has been reached.
        MessageFormatException - if this type conversion is invalid.
        MessageNotReadableException - if the message is in write-only mode.
        See Also:
        readBytes(byte[] value)

      • writeBoolean

        public void writeBoolean​(boolean value)
                  throws JMSException
        Writes a boolean to the stream message. The value true is written as the value (byte)1; the value false is written as the value (byte)0.
        Specified by:
        writeBoolean in interface StreamMessage
        Parameters:
        value - the boolean value to be written
        Throws:
        JMSException - if the JMS provider fails to write the message due to some internal error.
        MessageNotWriteableException - if the message is in read-only mode.

      • writeByte

        public void writeByte​(byte value)
               throws JMSException
        Writes a byte to the stream message.
        Specified by:
        writeByte in interface StreamMessage
        Parameters:
        value - the byte value to be written
        Throws:
        JMSException - if the JMS provider fails to write the message due to some internal error.
        MessageNotWriteableException - if the message is in read-only mode.

      • writeShort

        public void writeShort​(short value)
                throws JMSException
        Writes a short to the stream message.
        Specified by:
        writeShort in interface StreamMessage
        Parameters:
        value - the short value to be written
        Throws:
        JMSException - if the JMS provider fails to write the message due to some internal error.
        MessageNotWriteableException - if the message is in read-only mode.

      • writeChar

        public void writeChar​(char value)
               throws JMSException
        Writes a char to the stream message.
        Specified by:
        writeChar in interface StreamMessage
        Parameters:
        value - the char value to be written
        Throws:
        JMSException - if the JMS provider fails to write the message due to some internal error.
        MessageNotWriteableException - if the message is in read-only mode.

      • writeInt

        public void writeInt​(int value)
              throws JMSException
        Writes an int to the stream message.
        Specified by:
        writeInt in interface StreamMessage
        Parameters:
        value - the int value to be written
        Throws:
        JMSException - if the JMS provider fails to write the message due to some internal error.
        MessageNotWriteableException - if the message is in read-only mode.

      • writeLong

        public void writeLong​(long value)
               throws JMSException
        Writes a long to the stream message.
        Specified by:
        writeLong in interface StreamMessage
        Parameters:
        value - the long value to be written
        Throws:
        JMSException - if the JMS provider fails to write the message due to some internal error.
        MessageNotWriteableException - if the message is in read-only mode.

      • writeFloat

        public void writeFloat​(float value)
                throws JMSException
        Writes a float to the stream message.
        Specified by:
        writeFloat in interface StreamMessage
        Parameters:
        value - the float value to be written
        Throws:
        JMSException - if the JMS provider fails to write the message due to some internal error.
        MessageNotWriteableException - if the message is in read-only mode.

      • writeDouble

        public void writeDouble​(double value)
                 throws JMSException
        Writes a double to the stream message.
        Specified by:
        writeDouble in interface StreamMessage
        Parameters:
        value - the double value to be written
        Throws:
        JMSException - if the JMS provider fails to write the message due to some internal error.
        MessageNotWriteableException - if the message is in read-only mode.

      • writeBytes

        public void writeBytes​(byte[] value)
                throws JMSException
        Writes a byte array field to the stream message.

        The byte array value is written to the message as a byte array field. Consecutively written byte array fields are treated as two distinct fields when the fields are read.

        Specified by:
        writeBytes in interface StreamMessage
        Parameters:
        value - the byte array value to be written
        Throws:
        JMSException - if the JMS provider fails to write the message due to some internal error.
        MessageNotWriteableException - if the message is in read-only mode.

      • writeBytes

        public void writeBytes​(byte[] value,
                       int offset,
                       int length)
                throws JMSException
        Writes a portion of a byte array as a byte array field to the stream message.

        The a portion of the byte array value is written to the message as a byte array field. Consecutively written byte array fields are treated as two distinct fields when the fields are read.

        Specified by:
        writeBytes in interface StreamMessage
        Parameters:
        value - the byte array value to be written
        offset - the initial offset within the byte array
        length - the number of bytes to use
        Throws:
        JMSException - if the JMS provider fails to write the message due to some internal error.
        MessageNotWriteableException - if the message is in read-only mode.

      • writeObject

        public void writeObject​(Object value)
                 throws JMSException
        Writes an object to the stream message.

        This method works only for the objectified primitive object types (Integer, Double, Long ...), String objects, and byte arrays.

        Specified by:
        writeObject in interface StreamMessage
        Parameters:
        value - the Java object to be written
        Throws:
        JMSException - if the JMS provider fails to write the message due to some internal error.
        MessageFormatException - if the object is invalid.
        MessageNotWriteableException - if the message is in read-only mode.

      • reset

        public void reset()
           throws JMSException
        Puts the message body in read-only mode and repositions the stream of bytes to the beginning.
        Specified by:
        reset in interface StreamMessage
        Throws:
        JMSException - if an internal error occurs