public static void main(String[] args) throws Exception {Set<Class<?>> serviceClasses = new HashSet<>();serviceClasses.add(ServiceAImpl.class);serviceClasses.add(ServiceBImpl.class);ServiceA serviceA = createServiceA(serviceClasses);// call business logicSystem.out.println(serviceA.jobA());}

    private static ServiceA createServiceA(Set<Class<?>> serviceClasses) throws Exception{// step 1: create an instance of each service classSet<Object> serviceInstances = new HashSet<>();for(Class<?> serviceClass : serviceClasses){Constructor<?> constructor = serviceClass.getConstructor();constructor.setAccessible(true);serviceInstances.add(constructor.newInstance());}// step 2: wire them togetherfor(Object serviceInstance : serviceInstances){for(Field field : serviceInstance.getClass().getDeclaredFields()){Class<?> fieldType = field.getType();field.setAccessible(true);// find a suitable matching service instancefor(Object matchPartner : serviceInstances){if(fieldType.isInstance(matchPartner)){field.set(serviceInstance, matchPartner);}}}}// step 3: from all our service instances, find ServiceAfor(Object serviceInstance : serviceInstances){if(serviceInstance instanceof ServiceA){return (ServiceA)serviceInstance;}}// we didn't find the requested service instancereturn null;}

public class DIContext {private final Set<Object> serviceInstances = new HashSet<>();public DIContext(Collection<Class<?>> serviceClasses) throws Exception {// create an instance of each service classfor(Class<?> serviceClass : serviceClasses){Constructor<?> constructor = serviceClass.getConstructor();constructor.setAccessible(true);Object serviceInstance = constructor.newInstance();this.serviceInstances.add(serviceInstance);}// wire them togetherfor(Object serviceInstance : this.serviceInstances){for(Field field : serviceInstance.getClass().getDeclaredFields()){Class<?> fieldType = field.getType();field.setAccessible(true);// find a suitable matching service instancefor(Object matchPartner : this.serviceInstances){if(fieldType.isInstance(matchPartner)){field.set(serviceInstance, matchPartner);}}}}}@SuppressWarnings("unchecked")public <T> T getServiceInstance(Class<T> serviceClass){for(Object serviceInstance : this.serviceInstances){if(serviceClass.isInstance(serviceInstance)){return (T)serviceInstance;}}return null;}}

    public static void main(String[] args) throws Exception {DIContext context = createContext();doBusinessLogic(context);}private static DIContext createContext() throws Exception {Set<Class<?>> serviceClasses = new HashSet<>();serviceClasses.add(ServiceAImpl.class);serviceClasses.add(ServiceBImpl.class);return new DIContext(serviceClasses);}private static void doBusinessLogic(DIContext context){ServiceA serviceA = context.getServiceInstance(ServiceA.class);ServiceB serviceB = context.getServiceInstance(ServiceB.class);System.out.println(serviceA.jobA());System.out.println(serviceB.jobB());}

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;@Target(ElementType.FIELD)
@Retention(RetentionPolicy.RUNTIME)
public @interface Inject {}

public class ServiceAImpl implements ServiceA {@Injectprivate ServiceB serviceB;// rest is the same as before}

public class ServiceBImpl implements ServiceB {@Injectprivate ServiceA serviceA;// rest is the same as before}

       // wire them togetherfor(Object serviceInstance : this.serviceInstances){for(Field field : serviceInstance.getClass().getDeclaredFields()){// check that the field is annotatedif(!field.isAnnotationPresent(Inject.class)){// this field is none of our businesscontinue;}// rest is the same as before