JMSStreamMessage

 

public class JMSStreamMessage
extends JMSMessage
implements StreamMessage

java.lang.Object
   |
   +----com.ibm.jms.JMSMessage
           |
           +----com.ibm.jms.JMSStreamMessage
          

A StreamMessage is used to send a stream of Java™ primitives. It is filled and read sequentially. It inherits from JMSMessage 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 can also be read or written generically as objects. For example, 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 the reset() method has been made, the message body is in read-only mode. When a message has been sent the provider always calls the reset() method to read its content. Likewise, when a message has been received, the provider calls 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.

Stream messages support the following conversion table. The marked cases are supported and the unmarked cases throw a JMSException. The String to primitive conversions throw a runtime exception if the primitives 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 Java primitive type is treated as calling the primitive's corresponding valueOf(String) conversion method with a null value. Because char does not support a String conversion, attempting to read a null value as a char throws a NullPointerException.

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