struts2 원본 분석 - IOC 용기의 실현 메커니즘 (다음 편)

/**
   * Field and method injectors.
   */
  final Map<Class<?>, List<Injector>> injectors =
      new ReferenceCache<Class<?>, List<Injector>>() {
        @Override
        protected List<Injector> create(Class<?> key) {
          List<Injector> injectors = new ArrayList<Injector>();
          addInjectors(key, injectors);
          return injectors;
        }
      };

/**
   * {@inheritDoc}
   *
   * If this map does not contain an entry for the given key and {@link
   * #create(Object)} has been overridden, this method will create a new
   * value, put it in the map, and return it.
   *
   * @throws NullPointerException if {@link #create(Object)} returns null.
   * @throws java.util.concurrent.CancellationException if the creation is
   *  cancelled. See {@link #cancel()}.
   */
  @SuppressWarnings("unchecked")
  @Override public V get(final Object key) {
    V value = super.get(key);
    return (value == null)
      ? internalCreate((K) key)
      : value;
  }

FutureTask<V> futureTask = new FutureTask<V>(
          new CallableCreate(key));
// ...

futureTask.run();

/**
   * Recursively adds injectors for fields and methods from the given class to
   * the given list. Injects parent classes before sub classes.
   */
  void addInjectors(Class clazz, List<Injector> injectors) {
    if (clazz == Object.class) {
      return;
    }

    // Add injectors for superclass first.
    addInjectors(clazz.getSuperclass(), injectors);

    // TODO (crazybob): Filter out overridden members.
    addInjectorsForFields(clazz.getDeclaredFields(), false, injectors);
    addInjectorsForMethods(clazz.getDeclaredMethods(), false, injectors);
  }

<M extends Member & AnnotatedElement> void addInjectorsForMembers(
      List<M> members, boolean statics, List<Injector> injectors,
      InjectorFactory<M> injectorFactory) {
    for (M member : members) {
      if (isStatic(member) == statics) {
        Inject inject = member.getAnnotation(Inject.class);
        if (inject != null) {
          try {
            injectors.add(injectorFactory.create(this, member, inject.value()));
          } catch (MissingDependencyException e) {
            if (inject.required()) {
              throw new DependencyException(e);
            }
          }
        }
      }
    }
  }

void addInjectorsForFields(Field[] fields, boolean statics,
      List<Injector> injectors) {
    addInjectorsForMembers(Arrays.asList(fields), statics, injectors,
        new InjectorFactory<Field>() {
          public Injector create(ContainerImpl container, Field field,
              String name) throws MissingDependencyException {
            return new FieldInjector(container, field, name);
          }
        });
  }

public void inject(InternalContext context, Object o) {
      ExternalContext<?> previous = context.getExternalContext();
      context.setExternalContext(externalContext);
      try {
        field.set(o, factory.create(context));
      } catch (IllegalAccessException e) {
        throw new AssertionError(e);
      } finally {
        context.setExternalContext(previous);
      }
    }

/**
   * Gets an instance of the given dependency which was declared in
   * {@link com.opensymphony.xwork2.inject.ContainerBuilder}.
   */
  <T> T getInstance(Class<T> type, String name);

  /**
   * Convenience method. Equivalent to {@code getInstance(type,
   * DEFAULT_NAME)}.
   */
  <T> T getInstance(Class<T> type);

public <T> T getInstance(final Class<T> type, final String name) {
    return callInContext(new ContextualCallable<T>() {
      public T call(InternalContext context) {
        return getInstance(type, name, context);
      }
    });
  }

@SuppressWarnings("unchecked")
  <T> T getInstance(Class<T> type, String name, InternalContext context) {
    ExternalContext<?> previous = context.getExternalContext();
    Key<T> key = Key.newInstance(type, name);
    context.setExternalContext(ExternalContext.newInstance(null, key, this));
    try {
      InternalFactory o = getFactory(key);
      if (o != null) {
          return getFactory(key).create(context);
      } else {
          return null;
      }
    } finally {
      context.setExternalContext(previous);
    }
  }