I'm using Equinox Transforms to replace one class with a custom version of it on the classpath. The transforms mechanism seems to be working properly, and I return an InputStream of the custom class from public InputStream getInputStream(InputStream inputStream, URL transformerUrl) of my transformer class.
But the loading of that class then results in a ClassFormatError with message Truncated class file. The only thing I can imagine causing this is a mismatch between Java versions, but I've done everything I know how to do to eliminate that as a source of the problem, to no avail.
I removed all but one JDK from Eclipse in the Installed JREs preference. I made sure all the plug-ins involved have the same Java version for their execution environment and the JRE on the build path is specified with the same execution environment. Target and product execution environments are defined the same also. I did a clean all in the workspace and re-launched eclipse and my runtime workbench many times, with -clean. After all this, I still get the error.
What else could it be if not Java versions causing this error? The Equinox Transforms page says it can be used to transform class resources. Has anyone actually done that?
there is a more standardized way to replace a class in osgi, through a WeavingHook. This hook should be registered as a service, and have the possibility to dynamically enhance a class.
See the WeavingHook Javadoc or a concrete example with Aries Proxy, which dynamically create proxies with the help of asm (WovenProxyGenerator).