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先上示例圖：

代碼實(shí)現(xiàn)：

布局文件(Data-Binding模式)，很簡單就是兩行文字

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android">

    <RelativeLayout xmlns:tools="http://schemas.android.com/tools"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context="com.tnnowu.android.switchlanguage.MainActivity">

        <TextView
            android:id="@+id/titleTextView"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_centerInParent="true"
            android:text="@string/title"
            android:textSize="30sp"
            android:textStyle="bold" />

        <TextView
            android:id="@+id/descTextView"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_below="@+id/titleTextView"
            android:layout_centerHorizontal="true"
            android:layout_marginTop="10dp"
            android:text="@string/desc"
            android:textSize="20sp" />

    </RelativeLayout>

</layout>

從實(shí)例中我們可以看到右上角是有Menu

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    tools:context=".MainActivity">

    <item
        android:id="@+id/language_english"
        android:orderInCategory="100"
        android:title="@string/menu_english" />
    <item
        android:id="@+id/language_simplified_chinese"
        android:orderInCategory="100"
        android:title="@string/menu_simplified_chinese" />
    <item
        android:id="@+id/language_turkish"
        android:orderInCategory="100"
        android:title="@string/menu_turkish" />
    <item
        android:id="@+id/language_japanese"
        android:orderInCategory="100"
        android:title="@string/menu_japanese" />

</menu>

（既然是多語言，所以就要有N個(gè)strings）

，本案例我創(chuàng)建了4種語言。

好的，Menu的布局寫完了，接下來就是實(shí)現(xiàn)Menu功能，記住實(shí)現(xiàn)Menu就兩套代碼，一個(gè) onCreateOptionsMenu , 另一個(gè)是 onOptionsItemSelected 。

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    getMenuInflater().inflate(R.menu.menu, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    int id = item.getItemId();
    if (id == R.id.language_english) {
        updateViews("en");
    } else if (id == R.id.language_simplified_chinese) {
        updateViews("zh");
    } else if (id == R.id.language_turkish) {
        updateViews("tr");
    } else if (id == R.id.language_japanese) {
        updateViews("ja");
    }
    return super.onOptionsItemSelected(item);
}

在這里，可以看到，我們自定義一個(gè) updateViews() 方法，用來實(shí)現(xiàn)切換預(yù)言時(shí)界面的改變

private void updateViews(String languageCode) {
    Context context = LocaleHelper.setLocale(this, languageCode);
    Resources resources = context.getResources();

    mBinding.titleTextView.setText(resources.getString(R.string.title));
    mBinding.descTextView.setText(resources.getString(R.string.desc));

    setTitle(resources.getString(R.string.toolbar_title));
}

公布一個(gè) 語言判斷的類 LocaleHelper

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);

        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;

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

        return context;
    }
}

最后還要做的操作就是，自定義一個(gè)Application類，用來設(shè)定App的默認(rèn)語言(當(dāng)然了，要將這個(gè)Application應(yīng)用到Manifest中)

public class BaseApplication extends Application {

    @Override
    protected void attachBaseContext(Context base) {
        super.attachBaseContext(LocaleHelper.onAttach(base, "en"));
    }

}

本案例實(shí)現(xiàn)App內(nèi)語言切換代碼量不大，通俗易懂，無垃圾代碼。