Android实现应用内置语言切换功能

<resources> 
  <string name="app_name">SwitchLanguage</string> 
  <string name="helloworld">Hello World!</string> 
  <string name="language">Eng</string> 
  <string name="english">English</string> 
  <string name="chinese">中文</string> 
  <string name="russian">русский</string> 
  <string name="secondact">Second Activity</string> 
</resources> 

<resources> 
  <string name="app_name">Переключение язык</string> 
  <string name="helloworld">привет мир!</string> 
  <string name="language">русский</string> 
  <string name="secondact">второй активность</string> 
</resources> 

<resources> 
  <string name="app_name">切换语言</string> 
  <string name="helloworld">你好 世界!</string> 
  <string name="language">中文</string> 
  <string name="secondact">第二屏</string> 
</resources> 

<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout 
  android:id="@+id/activity_main" 
  xmlns:android="http://schemas.android.com/apk/res/android" 
  xmlns:tools="http://schemas.android.com/tools" 
  android:layout_width="match_parent" 
  android:layout_height="match_parent" 
  android:orientation="vertical" 
  tools:context="com.ce.switchlanguage.MainActivity" 
  xmlns:app="http://schemas.android.com/apk/res-auto"> 
  <android.support.design.widget.AppBarLayout 
    android:layout_height="wrap_content" 
    android:layout_width="match_parent" 
    android:theme="@style/AppTheme.AppBarOverlay"> 
 
    <android.support.v7.widget.Toolbar 
      android:id="@+id/toolbar" 
      android:layout_width="match_parent" 
      android:layout_height="?attr/actionBarSize" 
      android:background="?attr/colorPrimary" 
      app:popupTheme="@style/AppTheme.PopupOverlay" 
      app:title="@string/app_name"/> 
 
  </android.support.design.widget.AppBarLayout> 
  <TextView 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:text="@string/helloworld"/> 
  <Button 
    android:id="@+id/change" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:layout_gravity="center" 
    android:text="@string/language"/> 
</LinearLayout> 

<resources> 
  <style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar"> 
    <item name="colorPrimary">@color/colorPrimary</item> 
    <item name="colorPrimaryDark">@color/colorPrimaryDark</item> 
    <item name="colorAccent">@color/colorAccent</item> 
    <item name="windowActionBar">false</item> 
    <item name="windowNoTitle">true</item> 
    <item name="android:windowDisablePreview">true</item> 
  </style> 
  <style name="AppTheme.AppBarOverlay" parent="ThemeOverlay.AppCompat.Dark.ActionBar"/> 
  <style name="AppTheme.PopupOverlay" parent="ThemeOverlay.AppCompat.Dark"/> 
</resources> 

<?xml version="1.0" encoding="utf-8"?> 
<menu xmlns:android="http://schemas.android.com/apk/res/android" 
   xmlns:app="http://schemas.android.com/apk/res-auto"> 
  <item android:id="@+id/chinese" android:title="@string/chinese" app:showAsAction="never" /> 
  <item android:id="@+id/english" android:title="@string/english" app:showAsAction="never" /> 
  <item android:id="@+id/russian" android:title="@string/russian" app:showAsAction="never" /> 
</menu> 

package com.ce.switchlanguage; 
 
import android.content.Context; 
import android.content.SharedPreferences; 
import android.content.res.Configuration; 
import android.os.Build; 
import android.util.DisplayMetrics; 
 
import com.google.gson.Gson; 
 
import java.util.Locale; 
 
public class LocaleUtils { 
  /** 
   * 中文 
   */ 
  public static final Locale LOCALE_CHINESE = Locale.CHINESE; 
  /** 
   * 英文 
   */ 
  public static final Locale LOCALE_ENGLISH = Locale.ENGLISH; 
  /** 
   * 俄文 
   */ 
  public static final Locale LOCALE_RUSSIAN = new Locale("ru"); 
  /** 
   * 保存SharedPreferences的文件名 
   */ 
  private static final String LOCALE_FILE = "LOCALE_FILE"; 
  /** 
   * 保存Locale的key 
   */ 
  private static final String LOCALE_KEY = "LOCALE_KEY"; 
 
  /** 
   * 获取用户设置的Locale 
   * @param pContext Context 
   * @return Locale 
   */ 
  public static Locale getUserLocale(Context pContext) { 
    SharedPreferences _SpLocale = pContext.getSharedPreferences(LOCALE_FILE, Context.MODE_PRIVATE); 
    String _LocaleJson = _SpLocale.getString(LOCALE_KEY, ""); 
    return jsonToLocale(_LocaleJson); 
  } 
  /** 
   * 获取当前的Locale 
   * @param pContext Context 
   * @return Locale 
   */ 
  public static Locale getCurrentLocale(Context pContext) { 
    Locale _Locale; 
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) { //7.0有多语言设置获取顶部的语言 
      _Locale = pContext.getResources().getConfiguration().getLocales().get(0); 
    } else { 
      _Locale = pContext.getResources().getConfiguration().locale; 
    } 
    return _Locale; 
  } 
  /** 
   * 保存用户设置的Locale 
   * @param pContext Context 
   * @param pUserLocale Locale 
   */ 
  public static void saveUserLocale(Context pContext, Locale pUserLocale) { 
    SharedPreferences _SpLocal=pContext.getSharedPreferences(LOCALE_FILE, Context.MODE_PRIVATE); 
    SharedPreferences.Editor _Edit=_SpLocal.edit(); 
    String _LocaleJson = localeToJson(pUserLocale); 
    _Edit.putString(LOCALE_KEY, _LocaleJson); 
    _Edit.apply(); 
  } 
  /** 
   * Locale转成json 
   * @param pUserLocale UserLocale 
   * @return json String 
   */ 
  private static String localeToJson(Locale pUserLocale) { 
    Gson _Gson = new Gson(); 
    return _Gson.toJson(pUserLocale); 
  } 
  /** 
   * json转成Locale 
   * @param pLocaleJson LocaleJson 
   * @return Locale 
   */ 
  private static Locale jsonToLocale(String pLocaleJson) { 
    Gson _Gson = new Gson(); 
    return _Gson.fromJson(pLocaleJson, Locale.class); 
  } 
  /** 
   * 更新Locale 
   * @param pContext Context 
   * @param pNewUserLocale New User Locale 
   */ 
  public static void updateLocale(Context pContext, Locale pNewUserLocale) { 
    if (needUpdateLocale(pContext, pNewUserLocale)) { 
      Configuration _Configuration = pContext.getResources().getConfiguration(); 
      if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1) { 
        _Configuration.setLocale(pNewUserLocale); 
      } else { 
        _Configuration.locale =pNewUserLocale; 
      } 
      DisplayMetrics _DisplayMetrics = pContext.getResources().getDisplayMetrics(); 
      pContext.getResources().updateConfiguration(_Configuration, _DisplayMetrics); 
      saveUserLocale(pContext, pNewUserLocale); 
    } 
  } 
  /** 
   * 判断需不需要更新 
   * @param pContext Context 
   * @param pNewUserLocale New User Locale 
   * @return true / false 
   */ 
  public static boolean needUpdateLocale(Context pContext, Locale pNewUserLocale) { 
    return pNewUserLocale != null && !getCurrentLocale(pContext).equals(pNewUserLocale); 
  } 
} 

package com.ce.switchlanguage; 
 
import android.content.Intent; 
import android.os.Bundle; 
import android.support.v7.app.AppCompatActivity; 
import android.support.v7.widget.Toolbar; 
import android.view.Menu; 
import android.view.MenuItem; 
 
public class MainActivity extends AppCompatActivity { 
 
  @Override 
  protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main); 
    Toolbar _Toolbar =(Toolbar) findViewById(R.id.toolbar); 
    setSupportActionBar(_Toolbar); 
  } 
 
  @Override 
  public boolean onCreateOptionsMenu(Menu menu) { 
    getMenuInflater().inflate(R.menu.main_menu,menu); 
    return true; 
  } 
 
  @Override 
  public boolean onOptionsItemSelected(MenuItem item) { 
    int _ItemId=item.getItemId(); 
    switch (_ItemId) { 
      case R.id.chinese: 
        if (LocaleUtils.needUpdateLocale(this, LocaleUtils.LOCALE_CHINESE)) { 
          LocaleUtils.updateLocale(this, LocaleUtils.LOCALE_CHINESE); 
          restartAct(); 
        } 
        break; 
      case R.id.english: 
        if (LocaleUtils.needUpdateLocale(this, LocaleUtils.LOCALE_ENGLISH)) { 
          LocaleUtils.updateLocale(this, LocaleUtils.LOCALE_ENGLISH); 
          restartAct(); 
        } 
        break; 
      case R.id.russian: 
        if (LocaleUtils.needUpdateLocale(this, LocaleUtils.LOCALE_RUSSIAN)) { 
          LocaleUtils.updateLocale(this, LocaleUtils.LOCALE_RUSSIAN); 
          restartAct(); 
        } 
    } 
    return true; 
  } 
 
  /** 
   * 重启当前Activity 
   */ 
  private void restartAct() { 
    finish(); 
    Intent _Intent = new Intent(this, MainActivity.class); 
    startActivity(_Intent); 
    //清除Activity退出和进入的动画 
    overridePendingTransition(0, 0); 
  } 
} 

package com.ce.switchlanguage; 
 
import android.app.Application; 
import android.content.res.Configuration; 
import android.os.Build; 
 
import java.util.Locale; 
 
public class MyApplication extends Application { 
  @Override 
  public void onCreate() { 
    super.onCreate(); 
    Locale _UserLocale=LocaleUtils.getUserLocale(this); 
    LocaleUtils.updateLocale(this, _UserLocale); 
  } 
 
  @Override 
  public void onConfigurationChanged(Configuration newConfig) { 
    super.onConfigurationChanged(newConfig); 
    Locale _UserLocale=LocaleUtils.getUserLocale(this); 
    //系统语言改变了应用保持之前设置的语言 
    if (_UserLocale != null) { 
      Locale.setDefault(_UserLocale); 
      Configuration _Configuration = new Configuration(newConfig); 
      if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1) { 
        _Configuration.setLocale(_UserLocale); 
      } else { 
        _Configuration.locale =_UserLocale; 
      } 
      getResources().updateConfiguration(_Configuration, getResources().getDisplayMetrics()); 
    } 
  } 
}