Getting runtime class information from the web? Something like javap but at runtime on class loaded in memory

Question

I am working with Websphere and complicated classloading issues. I want to be able to download or print information that would normally get printed by javap (the methods, etc).

I may also need to get the raw binary class data, to perform a binary diff.

How would you do this?

There are some built in classloader diagnostics, accessibly through the console. Were they any use? — djna, Sep 08 '09 at 21:42
The reflection APIs (obj.getClass().getDeclaredMethods() and friends), should be able to get you most of what you want. — jsight, Sep 08 '09 at 22:10

score 1 · Accepted Answer · answered Sep 09 '09 at 06:53

You could write a Servlet or JMX MBean that exposes the class to the your client.

Servlet:

String resourceParameter = ...;
OutputStream out = ...:
InputStream input = Thread.currentThread().getContextClassLoader()
   .getResourceAsStream(resourceParameter)
write(input, out);

Client:

GET http://host/DiagnosticServlet?resource=your/ClassName.class

The resource parameter has to be your class file your.ClassName -> your/ClassName.class. You can then save the file and use javap.

(I think the MBean has to encode your class file into a string (e.g. Base 64) as byte[] is not supported. But I'm not sure about that. The rest would be the same.)

If this will be deployed in production some form of authentication should be configured.

Getting runtime class information from the web? Something like javap but at runtime on class loaded in memory

1 Answers1