Fragment和Activity生命周期以及横竖屏切换对生命周期的影响_onactivitycreated 横屏调用两次问题-优快云博客

本文链接：https://blog.youkuaiyun.com/robertcpp/article/details/51628794

本文详细探讨了Fragment和Activity的生命周期，特别关注横竖屏切换时对它们生命周期的影响。在不同AndroidManifest.xml配置下，Activity的生命周期方法调用次数和顺序有所不同。未设置`android:configChanges`时，横竖屏切换会导致生命周期方法多次调用；设置为`orientation`则只会调用一次；而设置为`orientation|keyboardHidden`则只会触发`onConfigurationChanged`方法。

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Fragment生命周期图解，fragment和activity生命周期对比

生命周期变化 : 切换到该Fragment

06-10 14:26:35.095: D/FragmentDemo(7649): onAttach
06-10 14:26:35.095: D/FragmentDemo(7649): onCreate
06-10 14:26:35.095: D/FragmentDemo(7649): onCreateView
06-10 14:26:35.100: D/FragmentDemo(7649): onActivityCreated
06-10 14:26:35.120: D/FragmentDemo(7649): onStart
06-10 14:26:35.120: D/FragmentDemo(7649): onResume

屏幕灭掉：
06-10 14:27:35.185: D/FragmentDemo(7649): onPause
06-10 14:27:35.205: D/FragmentDemo(7649): onSaveInstanceState
06-10 14:27:35.205: D/FragmentDemo(7649): onStop

屏幕解锁
06-10 14:33:13.240: D/FragmentDemo(7649): onStart
06-10 14:33:13.275: D/FragmentDemo(7649): onResume

切换到其他Fragment:
06-10 14:33:33.655: D/FragmentDemo(7649): onPause
06-10 14:33:33.655: D/FragmentDemo(7649): onStop
06-10 14:33:33.660: D/FragmentDemo(7649): onDestroyView

切换回本身的Fragment:
06-10 14:33:55.820: D/FragmentDemo(7649): onCreateView
06-10 14:33:55.825: D/FragmentDemo(7649): onActivityCreated
06-10 14:33:55.825: D/FragmentDemo(7649): onStart
06-10 14:33:55.825: D/FragmentDemo(7649): onResume

回到桌面
06-10 14:34:26.590: D/FragmentDemo(7649): onPause
06-10 14:34:26.880: D/FragmentDemo(7649): onSaveInstanceState
06-10 14:34:26.880: D/FragmentDemo(7649): onStop

回到应用
06-10 14:36:51.940: D/FragmentDemo(7649): onStart
06-10 14:36:51.940: D/FragmentDemo(7649): onResume

退出应用
06-10 14:37:03.020: D/FragmentDemo(7649): onPause
06-10 14:37:03.155: D/FragmentDemo(7649): onStop
06-10 14:37:03.155: D/FragmentDemo(7649): onDestroyView
06-10 14:37:03.165: D/FragmentDemo(7649): onDestroy

06-10 14:37:03.165: D/FragmentDemo(7649): onDetach

新建一个Activity，在各个生命周期中输出log
1、按crtl+f12切换成横屏时
onSaveInstanceState-->
onPause-->
onStop-->
onDestroy-->
onCreate-->
onStart-->
onRestoreInstanceState-->
onResume-->

2、再按crtl+f12切换成竖屏时，发现打印了两次相同的log
onSaveInstanceState-->
onPause-->
onStop-->
onDestroy-->
onCreate-->
onStart-->
onRestoreInstanceState-->
onResume-->
onSaveInstanceState-->
onPause-->
onStop-->
onDestroy-->
onCreate-->
onStart-->
onRestoreInstanceState-->
onResume-->

3、修改AndroidManifest.xml，把该Activity添加 Android:configChanges="orientation"，执行步骤2，横屏切换为竖屏
onSaveInstanceState-->
onPause-->
onStop-->
onDestroy-->
onCreate-->
onStart-->
onRestoreInstanceState-->
onResume-->

4、再执行步骤2，竖屏切换为横屏，发现不会再打印相同信息，但多打印了一行onConfigChanged
onSaveInstanceState-->
onPause-->
onStop-->
onDestroy-->
onCreate-->
onStart-->
onRestoreInstanceState-->
onResume-->
onConfigurationChanged-->

5、把步骤3的android:configChanges="orientation" 改成 android:configChanges="orientation|keyboardHidden"，执行步骤2，竖屏切换横屏，就只打印onConfigChanged
onConfigurationChanged-->

8、再次执行步骤2，横屏切换回竖屏
onConfigurationChanged-->

总结：
1、不设置Activity的android:configChanges时，切屏会重新调用各个生命周期，切横屏时会执行一次，切竖屏时会执行两次

2、设置Activity的android:configChanges="orientation"时，切屏还是会重新调用各个生命周期，切横、竖屏时只会执行一次