AttributeAccessor 

顶层接口，用于向任意对象附加元数据或从任意对象访问元数据

 

void setAttribute(String name, @Nullable Object value);

@Nullable

Object getAttribute(String name);

default <T> T computeAttribute(String name, Function<String, T> computeFunction); 默认实现：若name没有设置value，则触发computeFunction来得到value并setAttribute

@Nullable

Object removeAttribute(String name);

boolean hasAttribute(String name);

String[] attributeNames();