这是源码，通俗易懂，就贴出来了。

package android.app; import android.content.Context; import android.content.res.Configuration; import android.os.RemoteException; import android.os.ServiceManager; import android.util.Log; /** * 这个类提供系统UI模式服务的途径.这个服务允许应用控制设备的UI模式. * 提供设置行车模式和夜间模式的功能. * * 这个功能是构建在广播的基础上：当用户把设备放进一个地方或从中取出 * {@link android.content.Intent#ACTION_DOCK_EVENT} .这个时候, * the UiModeManager 会切换系统 {@link android.content.res.Configuration} * 进入设置 UI 模式, 发送进入此模式的广播, 并且开始在适应此时的模式. * 参看广播 {@link #ACTION_ENTER_CAR_MODE} 和 * {@link #ACTION_ENTER_DESK_MODE} 获取更多信息. * * 另外, 用户也可以手动切换模式.While in car mode -- whether by manual action * from the user or being physically placed in a dock -- a notification is * displayed allowing the user to exit dock mode.Thus the dock mode * represented here may be different than the current state of the underlying * dock event broadcast. * * 不可以直接实例化这个类; 通过 * {@link android.content.Context#getSystemService * Context.getSystemService(Context.UI_MODE_SERVICE)}获取这个服务. */ public class UiModeManager { private static final String TAG = "UiModeManager"; /** * 当设备UI进入行车模式，发送广播, either * by being placed in a car dock or explicit action of the user.After * sending the broadcast, the system will start the intent * {@link android.content.Intent#ACTION_MAIN} with category * {@link android.content.Intent#CATEGORY_CAR_DOCK} * to display the car UI, which typically what an application would * implement to provide their own interface.However, applications can * also monitor this Intent in order to be informed of mode changes or * prevent the normal car UI from being displayed by setting the result * of the broadcast to {@link Activity#RESULT_CANCELED}. */ public static String ACTION_ENTER_CAR_MODE = "android.app.action.ENTER_CAR_MODE"; /** * 当设备UI离开行车模式回到正常模式，发送广播.Typically used by a car mode app, to dismiss itself * when the user exits car mode. */ public static String ACTION_EXIT_CAR_MODE = "android.app.action.EXIT_CAR_MODE"; /** * Broadcast sent when the device's UI has switched to 夜间模式, * by being placed in a desk dock.After * sending the broadcast, the system will start the intent * {@link android.content.Intent#ACTION_MAIN} with category * {@link android.content.Intent#CATEGORY_DESK_DOCK} * to display the desk UI, which typically what an application would * implement to provide their own interface.However, applications can * also monitor this Intent in order to be informed of mode changes or * prevent the normal desk UI from being displayed by setting the result * of the broadcast to {@link Activity#RESULT_CANCELED}. */ public static String ACTION_ENTER_DESK_MODE = "android.app.action.ENTER_DESK_MODE"; /** * Broadcast sent when the device's UI has switched 离开夜间模式回到正常模式.Typically used by a desk mode app, to dismiss itself * when the user exits desk mode. */ public static String ACTION_EXIT_DESK_MODE = "android.app.action.EXIT_DESK_MODE"; /** Constant for {@link #setNightMode(int)} and {@link #getNightMode()}: * automatically switch night mode on and off based on the time. */ public static final int MODE_NIGHT_AUTO = Configuration.UI_MODE_NIGHT_UNDEFINED >> 4; /** Constant for {@link #setNightMode(int)} and {@link #getNightMode()}: * never run in night mode. */ public static final int MODE_NIGHT_NO = Configuration.UI_MODE_NIGHT_NO >> 4; /** Constant for {@link #setNightMode(int)} and {@link #getNightMode()}: * always run in night mode. */ public static final int MODE_NIGHT_YES = Configuration.UI_MODE_NIGHT_YES >> 4; private IUiModeManager mService; /*package*/ UiModeManager() { mService = IUiModeManager.Stub.asInterface( ServiceManager.getService(Context.UI_MODE_SERVICE)); }/** * Flag for use with {@link #enableCarMode(int)}: go to the car * home activity as part of the enable.Enabling this way ensures * a clean transition between the current activity (in non-car-mode) and * the car home activity that will serve as home while in car mode.This * will switch to the car home activity even if we are already in car mode. */ public static final int ENABLE_CAR_MODE_GO_CAR_HOME = 0x0001; /** * Flag for use with {@link #enableCarMode(int)}: allow sleep mode while in car mode. * By default, when this flag is not set, the system may hold a full wake lock to keep the * screen turned on and prevent the system from entering sleep mode while in car mode. * Setting this flag disables such behavior and the system may enter sleep mode * if there is no other user activity and no other wake lock held. * Setting this flag can be relevant for a car dock application that does not require the * screen kept on. */ public static final int ENABLE_CAR_MODE_ALLOW_SLEEP = 0x0002; /** * 使设备进入行车模式, like it had been placed in the car dock. * This will cause the device to switch to the car home UI as part of * the mode switch. * @param flags 必须为 0. */ public void enableCarMode(int flags) { if (mService != null) { try { mService.enableCarMode(flags); } catch (RemoteException e) { Log.e(TAG, "disableCarMode: RemoteException", e); } } }/** * Flag for use with {@link #disableCarMode(int)}: go to the normal * home activity as part of the disable.Disabling this way ensures * a clean transition between the current activity (in car mode) and * the original home activity (which was typically last running without * being in car mode). */ public static final int DISABLE_CAR_MODE_GO_HOME = 0x0001; /** * 如果当前在行车模式，关闭这个模式.参数可以为0：退出此模式；DISABLE_CAR_MODE_GO_HOME：退出此模式并返回桌面 * @param flags May be 0 or {@link #DISABLE_CAR_MODE_GO_HOME}. */ public void disableCarMode(int flags) { if (mService != null) { try { mService.disableCarMode(flags); } catch (RemoteException e) { Log.e(TAG, "disableCarMode: RemoteException", e); } } }/** * 返回当前运行的模式.可以为： * {@link Configuration#UI_MODE_TYPE_NORMAL Configuration.UI_MODE_TYPE_NORMAL}, * {@link Configuration#UI_MODE_TYPE_DESK Configuration.UI_MODE_TYPE_DESK}, * {@link Configuration#UI_MODE_TYPE_CAR Configuration.UI_MODE_TYPE_CAR}, * {@link Configuration#UI_MODE_TYPE_TELEVISION Configuration.UI_MODE_TYPE_TELEVISION}, * {@link Configuration#UI_MODE_TYPE_APPLIANCE Configuration.UI_MODE_TYPE_APPLIANCE}, or * {@link Configuration#UI_MODE_TYPE_WATCH Configuration.UI_MODE_TYPE_WATCH}. */ public int getCurrentModeType() { if (mService != null) { try { return mService.getCurrentModeType(); } catch (RemoteException e) { Log.e(TAG, "getCurrentModeType: RemoteException", e); } } return Configuration.UI_MODE_TYPE_NORMAL; }/**设置夜间模式。在API22及以下当在设备上同时也设置了行车模式或桌面模式，夜间模式才会生效。在API23及以上则没有这个限制 * * 模式可以为: *

*
• {@link #MODE_NIGHT_NO} - 日间模式 *mode.
*
• {@link #MODE_NIGHT_YES} - 夜间模式. *
*
• {@link #MODE_NIGHT_AUTO} - 自动切换，根据设备位置及相关传感器.
*

*/ public void setNightMode(int mode) { if (mService != null) { try { mService.setNightMode(mode); } catch (RemoteException e) { Log.e(TAG, "setNightMode: RemoteException", e); } } }/** * @return 返回当前配置的夜间模式. May be one of *{@link #MODE_NIGHT_NO}, {@link #MODE_NIGHT_YES}, *{@link #MODE_NIGHT_AUTO}, or -1 on error. */ public int getNightMode() { if (mService != null) { try { return mService.getNightMode(); } catch (RemoteException e) { Log.e(TAG, "getNightMode: RemoteException", e); } } return -1; } }