android 横竖屏切换生命周期调用

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(国际移动客户识别码)发生改变，检测到SIM卡，或者升级MCCmnc:The IMSI mobile network code (MNC) has changed — a SIM has been detected and updated the MNC.IMSI网络出现改变,检测到SIM卡，或者升级MCC其中mcc和mnc理论上不可能出现变化locale:The locale has changed — the user has selected a new language that text should be displayed in.语言出现改变，用户选择了一个新的语言，文字需要重新显示touchscreen:The touchscreen has changed. (This should never normally happen.)触摸屏发生改变，这一般是不需要出现的keyboard:The keyboard type has changed — for example, the user has plugged in an external keyboard.键盘类型出现改变，例如，用户使用了内部鼠标keyboardHidden:The keyboard accessibility has changed — for example, the user has revealed the hardware keyboard.键盘发生改变，例如，用户使用了软件鼠标navigation:The navigation type (trackball/dpad) has changed. (This should never normally happen.)导航发生改变，（这一般不需要出现） 举例：连接蓝牙按键，连接后确实造成了navigation的类型出现差异。

因为连接蓝牙鼠标后，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.屏幕的布局出现改变，这可能引起激活不同的显示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.设备翻转，横向显示和纵向显示机制切换。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提高了一个layoutDirection属性，当改变语言设定后，该属性也会成newConfig中的一个mask位。所以ActivityManagerService(实际在ActivityStack)在决定能否重启Activity的之后总是判断为重启。需要在android:configChanges 中同时添加locale和layoutDirection。在不退出应用的状况下切换到Settings里切换语言，发现该Activity还是重启了。

再来说说切屏生命周期状况Android 系统在Activity 生命周期中加入一些钩子，我们可以在很多平台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时读取。设置在该办法中，还以Bundle中可以强调用于建立该 Activity 所需的信息。onStart()：activity变为在屏幕上对用户可见时，即获取焦点时，会调用。onResume()：activity开始与用户交互时读取（无论是开启还是重新启动一个活动onresume 调用2次，该办法总是被调用的）。onPause()：activity被暂停或收回cpu和其他资源时读取，该办法用于储存活动状况的。。onStop()：activity被中止并转为不可见阶段及后续的生命周期事件时onresume 调用2次，即丧失焦点时读取。onRestart()：重新启动activity时读入。该活动仍在栈中，而不是启动新的活动。onDestroy()：activity被完全从平台存储中移除时读取，该办法被调用可能是因为有人直接调用 finish()方法 或者平台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onSaveInstanceStateonPauseonStoponDestroyonCreateonStartonRestoreInstanceStateonResumeonSaveInstanceStateonPauseonStoponDestroyonCreateonStartonRestoreInstanceStateonResume

3 修改AndroidManifest.xml，把该Activity添加 android:configChanges="orientation"，切横屏，只销毁一次。

onSaveInstanceStateonPauseonStoponDestroyonCreateonStartonRestoreInstanceStateonResume

4再切回竖屏，发现不会再打印相同信息，但多打印了一行onConfigChanged

onSaveInstanceStateonPauseonStoponDestroyonCreateonStartonRestoreInstanceStateonResumeonConfigurationChanged

5 更改 android:configChanges="orientation" 改成 android:configChanges="orientation|screenSize"，切横屏，就只打印onConfigChanged

onConfigurationChanged

6 切回竖屏

onConfigurationChangedonConfigurationChanged

总结：

1、不设定Activity的android:configChanges时，切屏会从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，切屏不会重新读取各个生命周期，只会执行onConfigurationChanged方法。（执行这个方式，必须设定sdk version 大于等于13.0）

本文来自电脑杂谈，转载请注明本文网址：
http://www.pc-fly.com/a/jisuanjixue/article-120007-1.html