public interface Subject {

 void test();
}

public class SubjectImpl implements Subject {

 @Override
 public void test() {
 System.out.println("This is test method");
 }
}

public class SubjectInvocationHandler implements InvocationHandler {

 private Subject target;

 public SubjectInvocationHandler(Subject subject) {
 this.target = subject;
 }

 @Override
 public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {

 System.out.println("before method!");

 Object result = method.invoke(target, args);

 System.out.println("after method!");

 return result;
 }
}

public class DynamicProxy {


 public static void main(String args[]) {

 Subject subject = new SubjectImpl();

 Subject proxy = (Subject) Proxy.newProxyInstance(SubjectImpl.class.getClassLoader(), SubjectImpl.class.getInterfaces(), new SubjectInvocationHandler(subject));
 proxy.test();

 System.out.println(proxy);
 }
}

before method! 
This is test method 
after method!