说到activity本身的性命周期
要区分几个概念
1 Activity 官方说明为 “An Activity is an application component that provides a screen with which users can interact in order to do something, such as dial the phone, take a photo, send an email, or view a map. Each activity is given a window in which to draw its
user interface. ”也就是用户用来交互的每一个窗口，用户当前正在进行的一个操作。
1 Activity 官方说明为 “An
