Java 类com.google.inject.internal.InternalInjectorCreator 实例源码

/**
 * Creates an injector for the given set of modules, in a given development
 * stage.
 *
 * @throws CreationException if one or more errors occur during injector
 *     construction
 */
public static Injector createInjector(Stage stage,
    Iterable<? extends Module> modules) {
  return new InternalInjectorCreator()
      .stage(stage)
      .addModules(modules)
      .build();
}

/**
 * Creates an injector for the given set of modules, in a given development
 * stage.
 *
 * @throws CreationException if one or more errors occur during injector
 *     construction
 */
public static Injector createInjector(Stage stage,
    Iterable<? extends Module> modules) {
  return new InternalInjectorCreator()
      .stage(stage)
      .addModules(modules)
      .build();
}

public <T> Provider<T> scope(final Key<T> key, final Provider<T> creator) {
  return new Provider<T>() {
    /*
     * The lazily initialized singleton instance. Once set, this will either have type T or will
     * be equal to NULL.
     */
    private volatile Object instance;

    // DCL on a volatile is safe as of Java 5, which we obviously require.
    @SuppressWarnings("DoubleCheckedLocking")
    public T get() {
      if (instance == null) {
        /*
         * Use a pretty coarse lock. We don't want to run into deadlocks
         * when two threads try to load circularly-dependent objects.
         * Maybe one of these days we will identify independent graphs of
         * objects and offer to load them in parallel.
         *
         * This block is re-entrant for circular dependencies.
         */
        synchronized (InternalInjectorCreator.class) {
          if (instance == null) {
            T provided = creator.get();

            // don't remember proxies; these exist only to serve circular dependencies
            if (isCircularProxy(provided)) {
              return provided;
            }

            Object providedOrSentinel = (provided == null) ? NULL : provided;
            if (instance != null && instance != providedOrSentinel) {
              throw new ProvisionException(
                  "Provider was reentrant while creating a singleton");
            }

            instance = providedOrSentinel;
          }
        }
      }

      Object localInstance = instance;
      // This is safe because instance has type T or is equal to NULL
      @SuppressWarnings("unchecked")
      T returnedInstance = (localInstance != NULL) ? (T) localInstance : null;
      return returnedInstance;
    }

    @Override
    public String toString() {
      return String.format("%s[%s]", creator, SINGLETON);
    }
  };
}

public <T> Provider<T> scope(final Key<T> key, final Provider<T> creator) {
  return new Provider<T>() {
    /*
     * The lazily initialized singleton instance. Once set, this will either have type T or will
     * be equal to NULL.
     */
    private volatile Object instance;

    // DCL on a volatile is safe as of Java 5, which we obviously require.
    @SuppressWarnings("DoubleCheckedLocking")
    public T get() {
      if (instance == null) {
        /*
         * Use a pretty coarse lock. We don't want to run into deadlocks
         * when two threads try to load circularly-dependent objects.
         * Maybe one of these days we will identify independent graphs of
         * objects and offer to load them in parallel.
         *
         * This block is re-entrant for circular dependencies.
         */
        synchronized (InternalInjectorCreator.class) {
          if (instance == null) {
            T provided = creator.get();

            // don't remember proxies; these exist only to serve circular dependencies
            if (isCircularProxy(provided)) {
              return provided;
            }

            Object providedOrSentinel = (provided == null) ? NULL : provided;
            if (instance != null && instance != providedOrSentinel) {
              throw new ProvisionException(
                  "Provider was reentrant while creating a singleton");
            }

            instance = providedOrSentinel;
          }
        }
      }

      Object localInstance = instance;
      // This is safe because instance has type T or is equal to NULL
      @SuppressWarnings("unchecked")
      T returnedInstance = (localInstance != NULL) ? (T) localInstance : null;
      return returnedInstance;
    }

    @Override
    public String toString() {
      return String.format("%s[%s]", creator, SINGLETON);
    }
  };
}

/**
 * Creates an injector for the given set of modules, in a given development stage.
 *
 * @throws CreationException if one or more errors occur during injector construction
 */
public static Injector createInjector(Stage stage, Iterable<? extends Module> modules) {
  return new InternalInjectorCreator().stage(stage).addModules(modules).build();
}