EventObject
↑
AWT Event
↑
Component Event | Action Event | Adjustment Event | Item Event
↑
Input Event | Focus Event | Paint Event | Window Event
↑
Mouse Event | Key Event
↑
MouseWheel Event

EventObject类有一个子类AWTEvent,它是所有AWT事件类的父类.
有些Swing组件将生成其他事件类型的事件对象;它们都真接扩展于EventObject,而不是AWTEvent.
事件对象封装了事件源与监听器彼此通信的事件信息.在必要的时候,可以对传给监听器对象的事件对象过行分析.