夜间模式 values-night

import android.app.Activity;
import android.content.SharedPreferences;
import android.content.res.Configuration;
import android.preference.PreferenceManager;

import java.lang.ref.WeakReference;

/**
 * Night Mode Helper
 * 

 * Helps use utilise the night and notnight resource qualifiers without being in car or dock mode.
 * 

 * Implementation is simple. Add the follow line at the top of your activity's onCreate just after
 * the super.onCreate(); The idea here is to do it before we create any views. So the new views will
 * use the correct Configuration.
 * 
 * 
 * mNightModeHelper = new NightModeHelper(this, R.style.AppTheme);
 * 
 * 
 * You can now use your instance of NightModeHelper to control which mode you are in. You can choose
 * to persist the current setting and hand it back to this class as the defaultUiMode, otherwise
 * this is done for you automatically.
 * 

 * I'd suggest you setup your Theme as follows:
 * 

 * 
res\values\styles.xml
 * 
 * 
 * <style name="AppTheme" parent="AppBaseTheme"></style>
 * 
 * 
 * 
 * 
res\values-night\styles.xml
 * 
 * 
 * <style name="AppBaseTheme" parent="@android:style/Theme.Holo"></style>
 * 
 * 
 * 
 * 
res\values-notnight\styles.xml
 * 
 * 
 * <style name="AppBaseTheme" parent="@android:style/Theme.Holo.Light"></style>
 * 
 * 
 * 
 * 
 * 
 * @author Simon Lightfoot 
 */
public class NightModeHelper {
    private static final String PREF_KEY = "nightModeState";

    private static int sUiNightMode = Configuration.UI_MODE_NIGHT_UNDEFINED;

    private WeakReference mActivity;
    private SharedPreferences mPrefs;

    /**
     * Default behaviour is to automatically save the setting and restore it.
     */
    public NightModeHelper(Activity activity, int theme) {
        int currentMode = (activity.getResources().getConfiguration().uiMode
                & Configuration.UI_MODE_NIGHT_MASK);
        mPrefs = PreferenceManager.getDefaultSharedPreferences(activity);
        init(activity, theme, mPrefs.getInt(PREF_KEY, currentMode));
    }

    /**
     * If you don't want the autoSave feature and instead want to provide your own persisted storage
     * for the mode, use the defaultUiMode for it.
     */
    public NightModeHelper(Activity activity, int theme, int defaultUiMode) {
        init(activity, theme, defaultUiMode);
    }

    public static int getUiNightMode() {
        return sUiNightMode;
    }

    private void init(Activity activity, int theme, int defaultUiMode) {
        mActivity = new WeakReference(activity);
        if (sUiNightMode == Configuration.UI_MODE_NIGHT_UNDEFINED) {
            sUiNightMode = defaultUiMode;
        }
        updateConfig(sUiNightMode);

        // This may seem pointless but it forces the Theme to be reloaded
        // with new styles that would change due to new Configuration.
        activity.setTheme(theme);
    }

    private void updateConfig(int uiNightMode) {
        Activity activity = mActivity.get();
        if (activity == null) {
            throw new IllegalStateException("Activity went away?");
        }
        Configuration newConfig = new Configuration(activity.getResources().getConfiguration());
        newConfig.uiMode &= ~Configuration.UI_MODE_NIGHT_MASK;
        newConfig.uiMode |= uiNightMode;
        activity.getResources().updateConfiguration(newConfig, null);
        sUiNightMode = uiNightMode;
        if (mPrefs != null) {
            mPrefs.edit()
                    .putInt(PREF_KEY, sUiNightMode)
                    .apply();
        }
    }

    public void toggle() {
        if (sUiNightMode == Configuration.UI_MODE_NIGHT_YES) {
            notNight();
        } else {
            night();
        }
    }

    public void notNight() {
        updateConfig(Configuration.UI_MODE_NIGHT_NO);
        mActivity.get().recreate();
    }

    public void night() {
        updateConfig(Configuration.UI_MODE_NIGHT_YES);
        mActivity.get().recreate();
    }
}

转自https://gist.github.com/slightfoot/c508cdc8828a478572e0