android 横竖屏切换生命周期调用

1、先来看看android:configChanges属性android:configChanges=["mcc", "mnc", "locale","touchscreen", "keyboard", "keyboardHidden","navigation", "screenLayout", "fontScale", "uiMode","orientation", "screenSize", "smallestScreenSize"]mcc:The IMSI mobile country code (MCC) has changed — a SIM has been detected and updated the MCC.IMSI(国际移动用户识别码)发生改变，检测到SIM卡，或者更新MCCmnc:The IMSI mobile network code (MNC) has changed — a SIM has been detected and updated the MNC.IMSI网络发生改变,检测到SIM卡，或者更新MCC其中mcc和mnc理论上不可能发生变化locale:The locale has changed — the user has selected a new language that text should be displayed in.语言发生改变，用户选择了一个新的语言，文字应该重新显示touchscreen:The touchscreen has changed. (This should never normally happen.)触摸屏发生改变，这通常是不应该发生的keyboard:The keyboard type has changed — for example, the user has plugged in an external keyboard.键盘类型发生改变，例如，用户使用了外部键盘keyboardHidden:The keyboard accessibility has changed — for example, the user has revealed the hardware keyboard.键盘发生改变，例如，用户使用了硬件键盘navigation:The navigation type (trackball/dpad) has changed. (This should never normally happen.)导航发生改变，（这通常不应该发生） 举例：连接蓝牙键盘，连接后确实导致了navigation的类型发生变化。因为连接蓝牙键盘后，我可以使用方向键来navigate了screenLayout：The screen layout has changed — this might be caused by a different display being activated.屏幕的布局发生改变，这可能导致激活不同的显示fontScale：The font scaling factor has changed — the user has selected a new global font size.全局字体大小缩放发生改变orientation：The screen orientation has changed — that is, the user has rotated the device.设备旋转，横向显示和竖向显示模式切换。screenSize: 屏幕大小改变了smallestScreenSize: 屏幕的物理大小改变了，如：连接到一个外部的屏幕上4.2增加了一个layoutDirection属性，当改变语言设置后，该属性也会成newConfig中的一个mask位。所以ActivityManagerService(实际在ActivityStack)在决定是否重启Activity的时候总是判断为重启。需要在android:configChanges 中同时添加locale和layoutDirection。在不退出应用的情况下切换到Settings里切换语言，发现该Activity还是重启了。

2、再来看看切屏生命周期状况Android 系统在Activity 生命周期中加入一些钩子，我们可以在这些系统预留的钩子中做一些事情。例举了 7 个常用的钩子：protected void onCreate(Bundle savedInstanceState)protected void onStart()protected void onResume()protected void onPause()protected void onStop()protected void onRestart()protected void onDestroy()简要说明：onCreate(Bundle savedInstanceState)：创建activity时调用。设置在该方法中，还以Bundle中可以提出用于创建该 Activity 所需的信息。onStart()：activity变为在屏幕上对用户可见时，即获得焦点时，会调用。onResume()：activity开始与用户交互时调用（无论是启动还是重新启动一个活动，该方法总是被调用的）。onPause()：activity被暂停或收回cpu和其他资源时调用，该方法用于保存活动状态的。。onStop()：activity被停止并转为不可见阶段及后续的生命周期事件时，即失去焦点时调用。onRestart()：重新启动activity时调用。该活动仍在栈中，而不是启动新的活动。onDestroy()：activity被完全从系统内存中移除时调用，该方法被调用可能是因为有人直接调用 finish()方法 或者系统决定停止该活动以释放资源。横竖屏切换1 切换到横屏onSaveInstanceStateonPauseonStoponDestroyonCreateonStartonRestoreInstanceStateonResume2 切换到竖屏，销毁了两次onSaveInstanceStateonPauseonStoponDestroyonCreateonStartonRestoreInstanceStateonResumeonSaveInstanceStateonPauseonStoponDestroyonCreateonStartonRestoreInstanceStateonResume3 修改AndroidManifest.xml，把该Activity添加 android:configChanges="orientation"，切横屏，只销毁一次。onSaveInstanceStateonPauseonStoponDestroyonCreateonStartonRestoreInstanceStateonResume4再切回竖屏，发现不会再打印相同信息，但多打印了一行onConfigChangedonSaveInstanceStateonPauseonStoponDestroyonCreateonStartonRestoreInstanceStateonResumeonConfigurationChanged5 更改 android:configChanges="orientation" 改成 android:configChanges="orientation|screenSize"，切横屏，就只打印onConfigChangedonConfigurationChanged6 切回竖屏onConfigurationChangedonConfigurationChanged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3、设置Activity的android:configChanges="orientation|screenSize"时，切屏不会重新调用各个生命周期，只会执行onConfigurationChanged方法。（执行这个方法，必须设置sdk version 大于等于13.0）