John,
Yes, I can certainly see that isBodyAssignableTo might be useful and am not opposed to adding it if there is general
support for it (the same applies to getBody()).
Nigel
On 26/10/2012 15:06, John D. Ament wrote:
> Nigel,
>
> In my opinion, having the ability to check if your method is going to throw an exception is useful. I prefer these
> checks rather than handling exceptions. But again that's just my opinion.
>
> John
>
> On Fri, Oct 26, 2012 at 10:00 AM, Nigel Deakin <nigel.deakin_at_oracle.com <mailto:nigel.deakin_at_oracle.com>> wrote:
>
> http://java.net/jira/browse/JMS_SPEC-101
> New method Message.getBody(Class<T> c)
>
> Following preceding discussions, I have changed the name of this method to getBody and polished the javadoc
> comment slightly. The updated API doc can be seen below and also at
> http://jms-spec.java.net/2.0-SNAPSHOT/apidocs/javax/jms/Message.html#getBody%28java.lang.Class%29
>
> In addition, I have taken up John A's suggestion and drafted an API doc for a method isBodyAssignableTo which can
> be used to find out whether a subsequent call to getBody would fail because of an incompatible type. The APi docs
> can be seen below and also at
> http://jms-spec.java.net/2.0-SNAPSHOT/apidocs/javax/jms/Message.html#isBodyAssignableTo%28java.lang.Class%29
>
> I think getBody() would be a nice addition to the API and is a useful complement to the new receivePayload
> methods. It would remove the need to cast a Message to a specific subtype in other cases such as in a
> MessageListener. However I would still welcome your views on this.
>
> I am less sure about isBodyAssignableTo. It is simple enough to define, but I'm not totally convinced there's a
> good case for adding it. Is this a useful complement to getBody, or is it simply bloat?
>
> So please express your views on the following:
>
> 1. Do you support the addition of Message.getBody() as defined below?
>
> 2. Do you support the addition of Message.isBodyAssignableTo() as defined below?
>
> Thanks,
>
> Nigel
>
> Here are those javadocs:
>
>
> /**
> * Returns the message body as an object of the specified type. The message
> * body must be capable of being assigned to the specified type. This means
> * that the specified class or interface must be either the same as, or a
> * superclass or superinterface of, the class of the message body. This
> * method may be used to obtain the body of any type of message except for
> * <tt>StreamMessage</tt>. If the message has no body then null is returned.
> *
> * @param c
> * The type to which the message body should be assigned. <br/>
> * If the message is a <code>TextMessage</code> then this should
> * be set to <code>String.class</code> or another class to which
> * a String is assignable. <br/>
> * If the message is a <code>ObjectMessage</code> then this
> * should be set to <code>java.io.Serializable.class</code> or
> * another class to which the payload is assignable. <br/>
> * If the message is a <code>MapMessage</code> then this should
> * be set to <code>java.util.Map.class</code>. <br/>
> * If the message is a <code>BytesMessage</code> then this should
> * be set to <code>byte[].class</code>. The
> * <code>BytesMessage</code> must not be in write-only mode.
> *
> * @return the message body
> *
> * @exception JMSException
> * if the JMS provider fails to get the message body due to
> * some internal error.
> * @exception MessageFormatException
> * if the message is a <code>StreamMessage</code>, or the
> * message body cannot be assigned to the specified type, or
> * the message is an <code>ObjectMessage</code> and object
> * deserialization fails.
> * @exception MessageNotReadableException
> * if the message is a <code>BytesMessage</code> and the
> * message is in write-only mode.
> */
> <T> T getBody(Class<T> c) throws JMSException;
>
> /**
> * Returns whether the message body is capable of being assigned to the
> * specified type. If this method returns true then a subsequent call to the
> * method <code>getBody</code> with the same type argument would not throw a
> * MessageFormatException.
> * <p>
> * If the message is a <code>StreamMessage</code> then false is returned. If
> * the message is a <code>ObjectMessage</code> and object deserialization
> * fails then false is returned. If the message has no body then true is
> * returned.
> *
> * @param c
> * The specified type <br/>
> * If the message is a <code>TextMessage</code> then method will
> * only return true if this parameter is set to
> * <code>String.class</code> or another class to which a String
> * is assignable. <br/>
> * If the message is a <code>ObjectMessage</code> then this
> * method will only return true if this parameter is set to
> * <code>java.io.Serializable.class</code> or another class to
> * which the payload is assignable. <br/>
> * If the message is a <code>MapMessage</code> then this method
> * will only return true if this parameter is set to
> * <code>java.util.Map.class</code>. <br/>
> * If the message is a <code>BytesMessage</code> then this this
> * method will only return true if this parameter is set to
> * <code>byte[].class</code>.
> *
> * @return whether the message body is capable of being assigned to the
> * specified type
> *
> * @exception JMSException
> * if the JMS provider fails to return a value due to some
> * internal error.
> * @exception MessageNotReadableException
> * if the message is a <code>BytesMessage</code> and the
> * message is in write-only mode.
> */
> boolean isBodyAssignableTo(Class c) throws JMSException;
>
>