Java Doc for StreamMessage.java in  » 6.0-JDK-Modules » JMS » javax » jms » Java Source Code / Java DocumentationJava Source Code and Java Documentation

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.
version:
   1.0 - 6 August 1998
author:
   Mark Hapner
author:
   Rich Burridge
See Also:   javax.jms.Session.createStreamMessage
See Also:   javax.jms.BytesMessage
See Also:   javax.jms.MapMessage
See Also:   javax.jms.Message
See Also:   javax.jms.ObjectMessage
See Also:   javax.jms.TextMessage

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. a Java object from the stream message, in objectifiedformat (for example, if the object was written as an int, an Integer is returned)
exception:
  JMSException - if the JMS provider fails to read the messagedue to some internal error.
exception:
  MessageEOFException - if unexpected end of message stream hasbeen reached.

The byte array value is written to the message as a byte array field.

The a portion of the byte array value is written to the message as a byte array field.

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.
Parameters:
  value - the buffer into which the data is read 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
exception:
  JMSException - if the JMS provider fails to read the messagedue to some internal error.
exception:
  MessageEOFException - if unexpected end of message stream hasbeen reached.
exception:
  MessageFormatException - if this type conversion is invalid.
exception:
  MessageNotReadableException - if the message is in write-only mode.
See Also:   StreamMessage.readObject()

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. a Java object from the stream message, in objectifiedformat (for example, if the object was written as an int, an Integer is returned)
exception:
  JMSException - if the JMS provider fails to read the messagedue to some internal error.
exception:
  MessageEOFException - if unexpected end of message stream hasbeen reached.
exception:
  MessageFormatException - if this type conversion is invalid.
exception:
  MessageNotReadableException - if the message is in write-only mode.
See Also:   StreamMessage.readBytes(byte[] value)

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.
Parameters:
  value - the byte array value to be written
exception:
  JMSException - if the JMS provider fails to write the messagedue to some internal error.
exception:
  MessageNotWriteableException - if the message is in read-only mode.

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.
Parameters:
  value - the byte array value to be written
Parameters:
  offset - the initial offset within the byte array
Parameters:
  length - the number of bytes to use
exception:
  JMSException - if the JMS provider fails to write the messagedue to some internal error.
exception:
  MessageNotWriteableException - if the message is in read-only mode.

This method works only for the objectified primitive object types (Integer, Double, Long ...), String objects, and byte arrays.
Parameters:
  value - the Java object to be written
exception:
  JMSException - if the JMS provider fails to write the messagedue to some internal error.
exception:
  MessageFormatException - if the object is invalid.
exception:
  MessageNotWriteableException - if the message is in read-only mode.