output.txt

Hello
intercept call to: public abstract java.lang.String de.tutorials.training.ReflectiveDefaultMethodCallExample$Hello.greet(java.lang.String)
Hello bubu

ReflectiveDefaultMethodCallExample.java

package de.tutorials.training;
 
import org.springframework.core.env.SystemEnvironmentPropertySource;

import java.lang.invoke.MethodHandles;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
 
/**
* [USER=136855]@author[/USER] Thomas Darimont
*/
public class ReflectiveDefaultMethodCallExample {
 
    static interface Hello {

        String greet(String arg);

        default String hello(String arg) {
            System.out.println("Hello");
            return greet(arg);
        }
    }
 
    public static void main(String[] args) throws Throwable{

        final Hello target = new Hello(){

            @Override
            public String greet(String arg) {
                return "Hello " + arg;
            }
        };

        Hello hello =
                (Hello)Proxy.newProxyInstance(Thread.currentThread().getContextClassLoader(),new Class[]{Hello.class},
                        (Object proxy, Method method, Object[] arguments) -> {
                            System.out.println("intercept call to: " + method);
                            return method.invoke(target,arguments);
                        });
        Method method = Hello.class.getMethod("hello", String.class);
 
        Object result = MethodHandles.lookup()
                                    .in(method.getDeclaringClass())
                                    .unreflectSpecial(method,method.getDeclaringClass())
                                    .bindTo(hello)
                                    .invokeWithArguments("bubu");
     
        System.out.println(result); //Hello bubu
    }
}