I do not think this is posiible. Session attributes are stored in a hashtable.
You cannot save null value to hashtable.
If you try session.setAttribute(myValue,null);
you will get null pointer exception with error 500.
I might have missed some thing, but take a look at package
org.apache.tomcat.session.
anil
Thomas Krebs wrote:
Hope, this wasn't discussed already (I browsed through the list but didn't
find it), if it was I apologize.
What is the expected result of calling setAttribute on an instance of
ServletRequest, if the attribute to be passed is null (i.e.
request.setAttribute(someName, null))?
I would expect that for the given name null is stored which would ensure
that a getAttribute call afterwards would return null as well.
However, the Tomcat implementation will leave the value unchanged:
--- code snippet from RequestImpl ---
Class org.apache.tomcat.core.RequestImpl.java line 614
public void setAttribute(String name, Object value) {
if(name!=null value!=null)
attributes.put(name, value);
}
--- end code snippet
Since other servlet container behave differently at least JRun does, namely
setting it to null, I wonder whether this is a bug in Tomcat?
I would argue that the expected behaviour is that getAttribute(name)
returns null, if a value for name was never set. In all other cases,
it should return exactly the value set with the last setAttribute call.
Any opinions on that?
best regards,
thomas
