Activity的生命周期

第一次进入Activity界面

D/MainActivity: onCreateD/MainActivity: onStart: D/MainActivity: onResume: 

跳转到下一个Activity界面

D/MainActivity: onPause: D/SecondActivity: OnCreate: D/SecondActivity: onStart: D/SecondActivity: onResume: D/MainActivity: onStop: 

返回上一个Activity界面

//注：此时是将第二个界面给finish了D/SecondActivity: onPause: D/MainActivity: onStart: D/MainActivity: onResume: D/SecondActivity: onStop: D/SecondActivity: onDestroy: 

手机睡眠时

D/MainActivity: onPause: D/MainActivity: onStop: 

睡眠状态消失时

D/MainActivity: onStart: D/MainActivity: onResume: 

按返回键退出app时

D/MainActivity: onPause: D/MainActivity: onStop: D/MainActivity: onDestroy: