sten-navie commented on issue #60:
URL: https://github.com/apache/felix-atomos/issues/60#issuecomment-1164154832
This does not seem to be related the equinox metatype implementation. I was
able to repeat the same problem, by writing a simple Activator that just tracks
javax.xml.parsers.SAXParserFactory. When receiving the reference I print out
some info about the received class vs the wanted class and then try to cast the
result, which again results in a ClassCastException:
```
g! lb
START LEVEL 1
ID|State |Level|Name
0|Active | 0|OSGi System Bundle
(3.17.200.v20220215-2237)|3.17.200.v20220215-2237
1|Active | 1|java.base (11.0.14)|11.0.14
2|Active | 1|java.compiler (11.0.14)|11.0.14
3|Active | 1|java.datatransfer (11.0.14)|11.0.14
4|Active | 1|java.desktop (11.0.14)|11.0.14
5|Active | 1|java.logging (11.0.14)|11.0.14
6|Active | 1|java.management (11.0.14)|11.0.14
7|Active | 1|java.management.rmi (11.0.14)|11.0.14
8|Active | 1|java.naming (11.0.14)|11.0.14
9|Active | 1|java.prefs (11.0.14)|11.0.14
10|Active | 1|java.rmi (11.0.14)|11.0.14
11|Active | 1|java.security.jgss (11.0.14)|11.0.14
12|Active | 1|java.security.sasl (11.0.14)|11.0.14
13|Active | 1|java.smartcardio (11.0.14)|11.0.14
14|Active | 1|java.xml (11.0.14)|11.0.14
15|Active | 1|java.xml.crypto (11.0.14)|11.0.14
16|Active | 1|jdk.charsets (11.0.14)|11.0.14
17|Active | 1|jdk.compiler (11.0.14)|11.0.14
18|Active | 1|jdk.crypto.cryptoki (11.0.14)|11.0.14
19|Active | 1|jdk.crypto.ec (11.0.14)|11.0.14
20|Active | 1|jdk.internal.opt (11.0.14)|11.0.14
21|Active | 1|jdk.jartool (11.0.14)|11.0.14
22|Active | 1|jdk.javadoc (11.0.14)|11.0.14
23|Active | 1|jdk.jdeps (11.0.14)|11.0.14
24|Active | 1|jdk.jfr (11.0.14)|11.0.14
25|Active | 1|jdk.jlink (11.0.14)|11.0.14
26|Active | 1|jdk.localedata (11.0.14)|11.0.14
27|Active | 1|jdk.management (11.0.14)|11.0.14
28|Active | 1|jdk.management.jfr (11.0.14)|11.0.14
29|Active | 1|jdk.naming.dns (11.0.14)|11.0.14
30|Active | 1|jdk.naming.rmi (11.0.14)|11.0.14
31|Active | 1|jdk.security.auth (11.0.14)|11.0.14
32|Active | 1|jdk.security.jgss (11.0.14)|11.0.14
33|Active | 1|jdk.unsupported.desktop (11.0.14)|11.0.14
34|Active | 1|jdk.zipfs (11.0.14)|11.0.14
35|Active | 1|atomos (1.0.0)|1.0.0
36|Active | 1|Apache Felix Gogo Command (1.1.0)|1.1.0
37|Active | 1|Apache Felix Gogo Runtime (1.1.2)|1.1.2
38|Active | 1|Apache Felix Gogo Shell (1.1.2)|1.1.2
39|Active | 1|osgi.core (0.0.0)|0.0.0
g! felix:install
file:///<REDACTED-PATH>/tmp/atomos-test/atomos-saxparser-test-1.0.0-SNAPSHOT.jar
Bundle ID: 40
g! felix:start 40
Starting SAX Test
Start tracking.
Wanted class : javax.xml.parsers.SAXParserFactory Module = unnamed module
@554f5786, Loader =
org.eclipse.osgi.internal.loader.EquinoxClassLoader@2097740[java.xml:11.0.14(id=14)]
Received impl class :
com.sun.org.apache.xerces.internal.jaxp.SAXParserFactoryImpl Module = module
java.xml, Loader = null
Super class : javax.xml.parsers.SAXParserFactory Module = module java.xml,
Loader = null
Super class : java.lang.Object Module = module java.base, Loader = null
Trying to cast
java.lang.ClassCastException: Cannot cast
com.sun.org.apache.xerces.internal.jaxp.SAXParserFactoryImpl to
javax.xml.parsers.SAXParserFactory
```
The relevant code (full code here
https://gist.github.com/sten-navie/278b2efa077d170fb530083c0648b2dd):
```
System.out.println("Starting SAX Test");
Class<SAXParserFactory> wantedClass = SAXParserFactory.class;
// use raw types, so that we do not immediately trigger a class-cast
exception via an implicit cast
serviceTracker = new ServiceTracker(bundleContext, wantedClass, new
ServiceTrackerCustomizer() {
@Override
public Object addingService(ServiceReference serviceReference) {
Object s = bundleContext.getService(serviceReference);
if (s == null) {
System.out.println("Got null ref!!!");
return null;
}
Class<?> implcl = s.getClass();
printClass("Wanted class", wantedClass);
printClass("Received impl class", implcl);
Class<?> supercl = implcl.getSuperclass();
while (supercl != null) {
printClass("Super class", supercl);
supercl = supercl.getSuperclass();
}
// try to cast
System.out.println("Trying to cast");
SAXParserFactory f = wantedClass.cast(s);
System.out.println("Cast successful. Done!");
return f;
}
```
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