一般在AndroidManifest.xml文件中都没有使用到android:configChanges="keyboardHidden|orientation"配置，当然还是很有用的。

就是如果配置了这个属性，当我们横竖屏切换的时候会直接调用onCreate方法中的onConfigurationChanged方法，而不会重新执行onCreate方法，那当然如果不配置这个属性的话就会重新调用onCreate方法了

 

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MCC

mnc: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。