这个功能是由谷歌为Android 13正式推出的(也有向后支持)。Android现在允许你为每个应用程序选择语言。

官方文件在这里- https://developer.android.com/guide/topics/resources/app-languages

要设置用户的首选语言，你会要求用户在语言选择器中选择一个地区，然后在系统中设置该值:

// 1. Inside an activity, in-app language picker gets an input locale "xx-YY"
// 2. App calls the API to set its locale
mContext.getSystemService(LocaleManager.class
    ).setApplicationLocales(newLocaleList(Locale.forLanguageTag("xx-YY")));
// 3. The system updates the locale and restarts the app, including any configuration updates
// 4. The app is now displayed in "xx-YY" language

要在语言选择器中显示用户当前的首选语言，你的应用程序可以从系统中获取返回的值:

// 1. App calls the API to get the preferred locale
LocaleList currentAppLocales =
    mContext.getSystemService(LocaleManager.class).getApplicationLocales();
// 2. App uses the returned LocaleList to display languages to the user

唯一完全适合我的解决方案是结合Alex Volovoy的代码和应用程序重启机制:

void restartApplication() {
    Intent i = new Intent(MainTabActivity.context, MagicAppRestart.class);
    i.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
    i.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
    MainTabActivity.context.startActivity(i);
}


/** This activity shows nothing; instead, it restarts the android process */
public class MagicAppRestart extends Activity {
    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        finish();
    }

    protected void onResume() {
        super.onResume();
        startActivityForResult(new Intent(this, MainTabActivity.class), 0);         
    }
}

我正在寻找一种以编程方式改变系统语言的方法。 虽然我完全理解一个正常的应用程序不应该这样做，而是:

用户应该(通过一个意图)指向系统设置手动更改它 应用程序应该自己处理本地化，就像Alex的回答中描述的那样

有必要从程序上真正改变系统的语言。

这是没有文档的API，因此不应该用于市场/最终用户应用程序!

不管怎样，这是我找到的解决方案:

  Locale locale = new Locale(targetLocaleAsString);

  Class amnClass = Class.forName("android.app.ActivityManagerNative");
  Object amn = null;
  Configuration config = null;

  // amn = ActivityManagerNative.getDefault();
  Method methodGetDefault = amnClass.getMethod("getDefault");
  methodGetDefault.setAccessible(true);
  amn = methodGetDefault.invoke(amnClass);

  // config = amn.getConfiguration();
  Method methodGetConfiguration = amnClass.getMethod("getConfiguration");
  methodGetConfiguration.setAccessible(true);
  config = (Configuration) methodGetConfiguration.invoke(amn);

  // config.userSetLocale = true;
  Class configClass = config.getClass();
  Field f = configClass.getField("userSetLocale");
  f.setBoolean(config, true);

  // set the locale to the new value
  config.locale = locale;

  // amn.updateConfiguration(config);
  Method methodUpdateConfiguration = amnClass.getMethod("updateConfiguration", Configuration.class);
  methodUpdateConfiguration.setAccessible(true);
  methodUpdateConfiguration.invoke(amn, config);

我知道现在回答有点晚了，但我在这里找到了这篇文章 ． 它很好地解释了整个过程，并为您提供了结构良好的代码。

Locale Helper类:

import android.annotation.TargetApi;
import android.content.Context;
import android.content.SharedPreferences;
import android.content.res.Configuration;
import android.content.res.Resources;
import android.os.Build;
import android.preference.PreferenceManager;

import java.util.Locale;

/**
 * This class is used to change your application locale and persist this change for the next time
 * that your app is going to be used.
 * <p/>
 * You can also change the locale of your application on the fly by using the setLocale method.
 * <p/>
 * Created by gunhansancar on 07/10/15.
 */
public class LocaleHelper {

    private static final String SELECTED_LANGUAGE = "Locale.Helper.Selected.Language";

    public static Context onAttach(Context context) {
        String lang = getPersistedData(context, Locale.getDefault().getLanguage());
        return setLocale(context, lang);
    }

    public static Context onAttach(Context context, String defaultLanguage) {
        String lang = getPersistedData(context, defaultLanguage);
        return setLocale(context, lang);
    }

    public static String getLanguage(Context context) {
        return getPersistedData(context, Locale.getDefault().getLanguage());
    }

    public static Context setLocale(Context context, String language) {
        persist(context, language);

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
            return updateResources(context, language);
        }

        return updateResourcesLegacy(context, language);
    }

    private static String getPersistedData(Context context, String defaultLanguage) {
        SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(context);
        return preferences.getString(SELECTED_LANGUAGE, defaultLanguage);
    }

    private static void persist(Context context, String language) {
        SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(context);
        SharedPreferences.Editor editor = preferences.edit();

        editor.putString(SELECTED_LANGUAGE, language);
        editor.apply();
    }

    @TargetApi(Build.VERSION_CODES.N)
    private static Context updateResources(Context context, String language) {
        Locale locale = new Locale(language);
        Locale.setDefault(locale);

        Configuration configuration = context.getResources().getConfiguration();
        configuration.setLocale(locale);
        configuration.setLayoutDirection(locale);

        return context.createConfigurationContext(configuration);
    }

    @SuppressWarnings("deprecation")
    private static Context updateResourcesLegacy(Context context, String language) {
        Locale locale = new Locale(language);
        Locale.setDefault(locale);

        Resources resources = context.getResources();

        Configuration configuration = resources.getConfiguration();
        configuration.locale = locale;
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1) {
            configuration.setLayoutDirection(locale);
        }

        resources.updateConfiguration(configuration, resources.getDisplayMetrics());

        return context;
    }
}

您需要重写attachBaseContext并调用LocaleHelper.onAttach()来初始化应用程序中的语言环境设置。

import android.app.Application;
import android.content.Context;

import com.gunhansancar.changelanguageexample.helper.LocaleHelper;

public class MainApplication extends Application {
    @Override
    protected void attachBaseContext(Context base) {
        super.attachBaseContext(LocaleHelper.onAttach(base, "en"));
    }
}

你所要做的就是相加

LocaleHelper.onCreate(this, "en");

只要你想改变locale。

这段代码真的可以工作:

fa = 波斯语，en = 英语

注意:语言代码不能有“-”，必须是2个小写字母

在languageToLoad变量中输入您的语言代码:

import android.app.Activity;
import android.content.res.Configuration;
import android.os.Bundle;

public class Main extends Activity {
  /** Called when the activity is first created. */
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    String languageToLoad  = "fa"; // your language
    Locale locale = new Locale(languageToLoad); 
    Locale.setDefault(locale);
    Configuration config = new Configuration();
    config.locale = locale;
    getBaseContext().getResources().updateConfiguration(config, 
      getBaseContext().getResources().getDisplayMetrics());
    this.setContentView(R.layout.main);
  }
}

2021年6月更新(Kotlin):

class Main : Activity() {
    // Called when the activity is first created.
    public override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        
        val config = resources.configuration
        val lang = "fa" // your language code
        val locale = Locale(lang)
        Locale.setDefault(locale)
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1)
            config.setLocale(locale)
        else
            config.locale = locale

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N)
            createConfigurationContext(config)
        resources.updateConfiguration(config, resources.displayMetrics)

        this.setContentView(R.layout.main)
    }
}

这是工作时，我按下按钮改变我的TextView的文本语言。(strings.xml在值-de文件夹)

String languageToLoad = "de"; // your language
Configuration config = getBaseContext().getResources().getConfiguration();
Locale locale = new Locale(languageToLoad);
Locale.setDefault(locale);
config.locale = locale;
getBaseContext().getResources().updateConfiguration(config, getBaseContext().getResources().getDisplayMetrics());
recreate();