While porting an application from WebLogic server to 4.0.0, I've noticed a strange feature of the server's classloader. Well, it was hard to miss a NullPointerException raised deep inside an EJB method call.... ;)
In brief, the problem is this: if jar file with my.test.package classes is stored in /lib directory of the configuration, java.lang.Package.getPackage( "my.test.package" ) call returns null, but Class.forName( "my.test.package.SomeClass" ).getPackage() returns the information from the jar's manifest.mf.
I tried moving the jar into my webapp's WEB-INF/lib, and in this case both calls returned valid results.
I wonder if the server can be configured in a way that allows access to manifest information of /lib jarfiles via Package.getPackage() calls... I suspect there should be some tricks, since in the array returned by Package.getPackages() there are entries that apparently correspond to some of the /lib jarfiles.
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The effect is easily reproducable in the default server configuration: I've put test.jsp (below) into server/default/jbossweb-tomcat50.sar/ROOT.war and put the jar into server/default/lib or ....ROOT.war/WEB-INF/lib.
test.jsp:
<html>
<body>
<%
Package pack = Class.forName( "mypackage.TestClass" ).getPackage();
if( pack ==null ) { %><h3>nulllllll</h3><%}
else
{
%><h3><%= pack.getName() %></h3>
<pre>Spec.title : <%= pack.getSpecificationTitle() %>
Spec.vendor : <%= pack.getSpecificationVendor() %>
pack.toString: <%= pack.toString() %>
</pre><%
}
pack = Package.getPackage( "mypackage" );
if( pack ==null ) { %><h3>nulllllll</h3><%}
else
{
%><h3><%= pack.getName() %></h3>
<pre>Spec.title : <%= pack.getSpecificationTitle() %>
Spec.vendor : <%= pack.getSpecificationVendor() %>
pack.toString: <%= pack.toString() %>
</pre><%
}
%>
</body>
</html>
