Activity生命周期之横竖屏切换

基础知识

下面讨论 API 12 以上的情况
（之前是不需要设置screenSize，并且可能与下面不一样）

关键在于 Activity中的一个属性configChanges（可以不写）

    <activity
        android:name=".activities.FirstActivity"
        android:configChanges="orientation"             
         />

1. 未设置configChanges，一般情况

1. 启动Activity，竖屏

   09-07 12:44:45.545 28409-28409/com.zero.androidtranningdemo D/FirstActivity﹕ onCreate First
   09-07 12:44:45.555 28409-28409/com.zero.androidtranningdemo D/FirstActivity﹕ onStart First
   09-07 12:44:45.555 28409-28409/com.zero.androidtranningdemo D/FirstActivity﹕ onResume First

2. 竖屏切换至横屏

   09-07 12:45:59.235 28409-28409/com.zero.androidtranningdemo D/FirstActivity﹕ onPause First
   09-07 12:45:59.235 28409-28409/com.zero.androidtranningdemo D/FirstActivity﹕ onSaveInstanceState First
   09-07 12:45:59.235 28409-28409/com.zero.androidtranningdemo D/FirstActivity﹕ onStop First
   09-07 12:45:59.235 28409-28409/com.zero.androidtranningdemo D/FirstActivity﹕ onDestroy First
   09-07 12:45:59.375 28409-28409/com.zero.androidtranningdemo D/FirstActivity﹕ onCreate First
   09-07 12:45:59.385 28409-28409/com.zero.androidtranningdemo D/FirstActivity﹕ onStart First
   09-07 12:45:59.385 28409-28409/com.zero.androidtranningdemo D/FirstActivity﹕ onRestoreInstanceState First
   09-07 12:45:59.385 28409-28409/com.zero.androidtranningdemo D/FirstActivity﹕ onResume First

3. 由横屏切换竖屏

   09-07 12:48:00.815 28409-28409/com.zero.androidtranningdemo D/FirstActivity﹕ onPause First
   09-07 12:48:00.815 28409-28409/com.zero.androidtranningdemo D/FirstActivity﹕ onSaveInstanceState First
   09-07 12:48:00.815 28409-28409/com.zero.androidtranningdemo D/FirstActivity﹕ onStop First
   09-07 12:48:00.815 28409-28409/com.zero.androidtranningdemo D/FirstActivity﹕ onDestroy First
   09-07 12:48:00.925 28409-28409/com.zero.androidtranningdemo D/FirstActivity﹕ onCreate First
   09-07 12:48:00.925 28409-28409/com.zero.androidtranningdemo D/FirstActivity﹕ onStart First
   09-07 12:48:00.925 28409-28409/com.zero.androidtranningdemo D/FirstActivity﹕ onRestoreInstanceState First
   09-07 12:48:00.925 28409-28409/com.zero.androidtranningdemo D/FirstActivity﹕ onResume First

2. 修改configChanges为

（一般广告SDK中使用）

android:configChanges="orientation|screenSize"

只会调用一个方法

09-07 12:57:41.295 9776-9776/com.zero.androidtranningdemo D/FirstActivity﹕ onConfigurationChanged

    @Override
    public void onConfigurationChanged(Configuration newConfig) {
        super.onConfigurationChanged(newConfig); //必须写上
        Log.d(TAG, "onConfigurationChanged");
    }