Re: Reflection: discovering the implementations of an interface

z-man wrote:


Of course, it should.

See the output of running the following agent:

import java.lang.instrument.Instrumentation;
import java.lang.reflect.Proxy;
import java.util.ArrayList;
import java.util.Arrays;

/**
  * After building agent's jar with duly manifest run it with:
  * java -javaagent:agent.jar ClassesAgent
  *
  * @author pk
  */
public class ClassesAgent {

     private static Instrumentation inst;

     public static void premain(String agentArgs, Instrumentation inst) {
         ClassesAgent.inst = inst;
     }

     public static Class[] getAllClassesAssignableFrom(Class...
interfaces) {
         ArrayList<Class> found = new ArrayList<Class>();
         loop: for (Class c : inst.getAllLoadedClasses()) {
             for (Class<?> ic : interfaces)
                 if (!ic.isAssignableFrom(c))
                     continue loop;
             found.add(c);
         }
         return found.toArray(new Class[found.size()]);
     }

     interface Test {}

     public static void main(String[] args) throws Exception {
         System.out.println("lookup of classes implementing " +
Test.class + "...");
         Class[] classes;
         classes = getAllClassesAssignableFrom(Test.class);
         System.out.println("classes found: " + Arrays.toString(classes));
         Class tic = Proxy.getProxyClass(
                 Test.class.getClassLoader(), Test.class);
         System.out.println("just generated: " + tic);
         classes = getAllClassesAssignableFrom(Test.class);
         System.out.println("classes found: " + Arrays.toString(classes));
     }

}

piotr