android:configChanges="orientation|keyboardHidden"的使用

1. 了解android:configChanges 的属性

     通过设置这个属性可以使Activity捕捉设备状态变化，以下是可以被识别的内容：  

     CONFIG_FONT_SCALE
     CONFIG_MCC
     CONFIG_MNC
     CONFIG_LOCALE
     CONFIG_TOUCHSCREEN
     CONFIG_KEYBOARD
     CONFIG_NAVIGATION
     CONFIG_ORIENTATION
设置方法：将下列字段用 “|” 符号分隔开，例如：“locale|navigation|orientation

Value	Description
“mcc“	The IMSI mobile country code (MCC) has changed — that is, a SIM hasbeen detected and updated the MCC.移动国家号码，由三位数字组成，每个国家都有自己独立的MCC，可以识别手机用户所属国家。
“mnc“	The IMSI mobile network code (MNC) has changed — that is, a SIM hasbeen detected and updated the MNC.移动网号，在一个国家或者地区中，用于区分手机用户的服务商。
“locale“	The locale has changed — for example, the user has selected a new language that text should be displayed in.用户所在地区发生变化。
“touchscreen“	The touchscreen has changed. (This should never normally happen.)
“keyboard“	The keyboard type has changed — for example, the user has plugged in an external keyboard.键盘模式发生变化，例如：用户接入外部键盘输入。
“keyboardHidden“	The keyboard accessibility has changed — for example, the user has slid the keyboard out to expose it.用户打开手机硬件键盘
“navigation“	The navigation type has changed. (This should never normally happen.)
“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。
“fontScale“	The font scaling factor has changed — that is, the user has selected a new global font size.全局字体大小缩放发生改变

        在Activity中添加了 android:configChanges属性，目的是当所指定属性(Configuration Changes)发生改变时，通知程序调用 onConfigurationChanged()函数。

2. android:configChanges="orientation|keyboardHidden"的使用 

   当在activity加上android:configChanges="keyboardHidden|orientation"属性,就不会重启activity.而只是调用onConfigurationChanged(Configuration newConfig).这样就可以在这个方法里调整显示方式.

在xml文件里面可以进行配置configChanges也可以在代码中动态配置 

注意：

   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|keyboardHidden"时，切屏不会重新调用各个生命周期，只会执行onConfigurationChanged方法