android 生命周期程序设计
设计程序运行过程，通过点击模拟器上的“返回键”、“呼出/接听键”、“挂断键”等，解释出三种不同生命周期中事件回调函数的执行顺序及作用。(Android lifecycle program design
By clicking on the "return key", "exhale / answer key" and "hang off key" on the simulator, the sequence and function of the execution of the event callback functions in three different life cycles are explained.)