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.
--------------------------------------
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>
|
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