temp

ContainerBuilder中的public Container create(boolean loadSingletons)
  ①   final ContainerImpl container = new ContainerImpl(
        new HashMap<Key<?>, InternalFactory<?>>(factories));
     this.factories = factories;
   ContainerImpl的构造方法中，用factories的Key部分构件一个新Map
      for (Key<?> key : factories.keySet()) {
      Set<String> names = map.get(key.getType());
      if (names == null) {
        names = new HashSet<String>();
        map.put(key.getType(), names);
      }
      names.add(key.getName());
    }

for (Entry<Class<?>,Set<String>> entry : map.entrySet()) {
      entry.setValue(Collections.unmodifiableSet(entry.getValue()));
    }
使Map的Value只读，即一些default、struts之类的值
Returns an unmodifiable view of the specified set. This method allows modules to provide users with "read-only" access to internal sets. Query operations on the returned set "read through" to the specified set, and attempts to modify the returned set, whether direct or via its iterator, result in an UnsupportedOperationException.

this.factoryNamesByType = Collections.unmodifiableMap(map)  不可修改

{type=class com.opensymphony.xwork2.ObjectFactory, name=default, implementation=class com.opensymphony.xwork2.ObjectFactory, scope=SINGLETON}

② container.callInContext(new ContainerImpl.ContextualCallable<Void>() {
        public Void call(InternalContext context) {
          for (InternalFactory<?> factory : singletonFactories) {
            factory.create(context);
          }
          return null;
        }
      })

callInContext    创建了一个InternalContext

匿名ContextualCallable的实例调用call（创建的InternalContext）
对单例工厂中的每个工厂，factory.create(context)