Android 多语言切换的一些bug与解决

参考：

1. http://www.lai18.com/content/6602031.html
2. https://jaeger.itscoder.com/android/2016/05/14/switch-language-on-android-app.html
3. http://gunhansancar.com/change-language-programmatically-in-android/

具体设置可参考：
https://jaeger.itscoder.com/android/2016/05/14/switch-language-on-android-app.html

具体bug的产生，可参考：
http://www.lai18.com/content/6602031.html

解决方案

如果代码中，没有基类，或者，不喜欢使用基类，可使用 activity生命周期callback来解决：

工具类代码:

public final class LocaleUtils {

    private static final String FILE_NAME = "better_language_info";
    private static final String KEY_LANGUAGE = "key_language";
    private static final String KEY_COUNTRY = "key_country";

    /**
     * 获取手机系统的Locale
     *
     * @return
     */
    public static Locale getSystemLocale() {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
            return LocaleList.getDefault().get(0);
        }
        return Locale.getDefault();
    }

    /**
     * 设置 App 的Locale
     *
     * @param context
     * @param loc
     * @return
     */
    public static void setAppLocale(Context context, Locale loc) {
        if (loc != null) {
            setUserSetLocale(context, loc);

            Resources rs = context.getResources();
            Configuration config = rs.getConfiguration();
            DisplayMetrics dm = rs.getDisplayMetrics();
            if (Build.VERSION.SDK_INT >= 17) {
                config.setLocale(loc);
            } else {
                config.locale = loc;
            }
            context.getResources().updateConfiguration(config, dm);
        }
    }

    /**
     * 在activity 的  onResume or onConfigChange中调用此方法
     * http://www.jianshu.com/p/47bbd34d2af8
     *
     * @param context
     * @param loc
     */
    public static void setLocaleWhenConfigChange(Context context, Locale loc) {
        if (loc != null) {
            Resources rs = context.getResources();
            Configuration config = rs.getConfiguration();
            DisplayMetrics dm = rs.getDisplayMetrics();
            if (Build.VERSION.SDK_INT >= 17) {
                config.setLocale(loc);
            } else {
                config.locale = loc;
            }
            context.getResources().updateConfiguration(config, dm);
        }
    }

    /**
     * 获取App Locale
     *
     * @param context
     * @return
     */
    public static Locale getAppLocale(Context context) {
        Configuration config = context.getResources().getConfiguration();
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N)
            return config.getLocales().get(0);
        else
            return config.locale;
    }

    /**
     * 获取用户设置的Locale
     *
     * @param context
     * @return
     */
    public static Locale getUserSetLocale(Context context) {
        SharedPreferences sp = context.getSharedPreferences(FILE_NAME, Context.MODE_PRIVATE);
        String lang = sp.getString(KEY_LANGUAGE, "");
        String country = sp.getString(KEY_COUNTRY, "");
        if (!TextUtils.isEmpty(lang) && !TextUtils.isEmpty(country)) {
            return new Locale(lang, country);
        }
        return null;
    }

    /**
     * 返回 en_US 格式
     *
     * @param context
     * @return
     */
    public static String getUserSetLocaleStr(Context context) {
        SharedPreferences sp = context.getSharedPreferences(FILE_NAME, Context.MODE_PRIVATE);
        String lang = sp.getString(KEY_LANGUAGE, "");
        String country = sp.getString(KEY_COUNTRY, "");
        if (!TextUtils.isEmpty(lang) && !TextUtils.isEmpty(country)) {
            return String.format("%s_%s", lang, country);
        }
        return "";
    }

    /**
     * 清空设置，跟随系统
     *
     * @param context
     */
    public static void removeLocaleSet(Context context) {
        SharedPreferences sp = context.getSharedPreferences(FILE_NAME, Context.MODE_PRIVATE);
        final SharedPreferences.Editor edit = sp.edit();
        edit.putString(KEY_LANGUAGE, "");
        edit.putString(KEY_COUNTRY, "");
        edit.apply();
    }

    /**
     * 用户设置的Locale
     */
    private static void setUserSetLocale(Context context, Locale locale) {
        if (locale != null) {
            try {
                SharedPreferences sp = context.getSharedPreferences(FILE_NAME, Context.MODE_PRIVATE);
                final SharedPreferences.Editor edit = sp.edit();
                edit.putString(KEY_LANGUAGE, locale.getLanguage());
                edit.putString(KEY_COUNTRY, locale.getCountry());
                edit.apply();
            } catch (Exception e) {
            }
        }
    }
}

1. app 启动设置在 application 调用如下方法：

  private static void setLocale(Context context) {
        final Locale userSet = LocaleUtils.getUserSetLocale(context);
        if (userSet != null && LocaleUtils.getAppLocale(context) != userSet) {
            LocaleUtils.setAppLocale(context, userSet);
        }
    }

2. 在 application类中，监听activity生命周期回调如下：

private void registerLifeActivityCallbacks() {
        registerActivityLifecycleCallbacks(new ActivityLifecycleCallbacks() {

            @Override
            public void onActivityResumed(Activity activity) {
             
                // 切换语言，修复bug
                final Locale userSetLocale = LocaleUtils.getUserSetLocale(activity);
                LocaleUtils.setLocaleWhenConfigChange(activity, userSetLocale);
            }

这种bugs 也是头痛，难道 google允许某一个页面，是中文，另一个页面是英文这种么？