top-level class

基本解释

AopRemovals, which prevents calls to specified methods from being executed, is the new top-level class.
它阻止指定方法的调用被执行，是一个新的顶级类。
A key annotation is @XmlRootElement, which maps a top-level class to a global element in the XML schema that is used by the WSDL of the Web service.
关键的注解是 @XmlRootElement，它把顶级类映射到 Web 服务的 WSDL 使用的 XML 模式中的全局元素。
Discovering the entire inheritance tree structure from an existing system is particularly useful, because it helps you uncover what the top-level class is and what subclasses are in the tree.
从一个已存在系统中发现整个的继承树结构是相当有用的，因为它能向您揭露在树中什么是顶级类以及什么是子类。