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>wrote:
> http://java.net/jira/browse/**JMS_SPEC-101<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<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<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;
>