android:configChanges="orientation|keyboard|keyboardHidden"
在AndroidManifest.xml中添加上述代码的含义是表示在改变屏幕方向、弹出软件盘和隐藏软键盘时，不再去执行onCreate()方法，而是直接执行onConfigurationChanged()
如果不申明此段代码，按照Activity的生命周期，都会去执行一次onCreate()方法，而onCreate()方法通常会在显示之前做一些初始化工作。所以如果改变屏幕方向这样的操作都去执行onCreate()方法，就有可能造成重复的初始化，降低程序效率是必然的了，而且更有可能因为重复的初始化而导致数据的丢失。这是需要千万避免的
重写的onConfigurationChanged()如下：
@Override
public void onConfigurationChanged(Configuration newConfig) {
//获取屏幕方向
int orientation = newConfig.orientation;
Log.d("Debug","orientation:"+orientation);
super.onConfigurationChanged(newConfig);
}
AndroidManifest中声明Android:configChanges属性，该属性规定了我们可以在程序中捕获到的事件类型
可选属性如下：
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 |
