Android如何动态调整应用字体大小详解

public class MainApplication extends Application implements Application.ActivityLifecycleCallbacks {
 private List<Activity> activityList;
 private float fontScale;
 private SharedPreferences preferences;
 private static MainApplication mainApplication;

 @Override
 public void onCreate() {
  super.onCreate();
  init();
 }

 private void init() {
  mainApplication = this;
  preferences = PreferenceManager.getDefaultSharedPreferences(this);
  fontScale = getFontScale();
  registerActivityLifecycleCallbacks(this);
 }

 public static float getFontScale() {
  float fontScale = 1.0f;
  if (mainApplication != null) {
   fontScale = mainApplication.preferences.getFloat("fontScale", 1.0f);
  }
  return fontScale;
 }

 @Override
 public void onActivityCreated(Activity activity, Bundle savedInstanceState) {
  if (activityList == null) {
   activityList = new ArrayList<>();
  }
  // 禁止字体大小随系统设置变化
  Resources resources = activity.getResources();
  if (resources != null && resources.getConfiguration().fontScale != fontScale) {
   android.content.res.Configuration configuration = resources.getConfiguration();
   configuration.fontScale = fontScale;
   resources.updateConfiguration(configuration, resources.getDisplayMetrics());
  }
  activityList.add(activity);
 }

 @Override
 public void onActivityStarted(Activity activity) {

 }

 @Override
 public void onActivityResumed(Activity activity) {

 }

 @Override
 public void onActivityPaused(Activity activity) {

 }

 @Override
 public void onActivityStopped(Activity activity) {

 }

 @Override
 public void onActivitySaveInstanceState(Activity activity, Bundle outState) {

 }

 @Override
 public void onActivityDestroyed(Activity activity) {
  if (activityList != null) {
   activityList.remove(activity);
  }
 }

 public static void setAppFontSize(float fontScale) {
  if (mainApplication != null) {
   List<Activity> activityList = mainApplication.activityList;
   if (activityList != null) {
    for (Activity activity : activityList) {
     if (activity instanceof SettingActivity) {
      continue;
     }
     Resources resources = activity.getResources();
     if (resources != null) {
      android.content.res.Configuration configuration = resources.getConfiguration();
      configuration.fontScale = fontScale;
      resources.updateConfiguration(configuration, resources.getDisplayMetrics());
      activity.recreate();
      if (fontScale != mainApplication.fontScale) {
       mainApplication.fontScale = fontScale;
       mainApplication.preferences.edit().putFloat("fontScale", fontScale).apply();
      }
     }
    }
   }
  }
 }
}