Android-語言設置流程分析

Android手機語言切換行為，是通過設置-語言和輸入法-語言來改變手機的語言，其實這個功能很少被用戶使用。

以Android5.1工程源碼為基礎,從設置app入手來分析和學習語言切換的過程:

一、語言設置界面：

首先在設置app中找到語言設置這個Preference，目前設置中界面大多都是Fragment，先找到語言和輸入法的PreferenceScreen，與其對應的Fragment是InputMethodAndLanguageSettings.java，在其onCreate()方法中，首先是增加語言設置的preference：? ??

addPreferencesFromResource(R.xml.language_settings);??

找到language_settings.xml，可發現如下代碼：? ?

<PreferenceScreen??
????????????android:key="phone_language"??
????????????android:title="@string/phone_language"??
????????????android:fragment="com.android.settings.LocalePicker"??
????????????/>??

于是斷定LocalePicker就是語言設置的Fragment，它是ListFragment的子類，繼承于framework中LocalePicker,并實現了父類的一個接口，其回調方法是onLocaleSelected()，Locale中文含義大致是語言環境，所以可推測這是設置語言后的一個回調方法，不確定的話，可打斷點測試一下。然而此類中并沒有關于語言設置界面數據適配的太多邏輯，只是通過父類的方法創建了一個view:? ?

@Override??
???public?View?onCreateView(??
???????????LayoutInflater?inflater,?ViewGroup?container,?Bundle?savedInstanceState)?{??
???????final?View?view?=?super.onCreateView(inflater,?container,?savedInstanceState);??
???????final?ListView?list?=?(ListView)?view.findViewById(android.R.id.list);??
???????Utils.forcePrepareCustomPreferencesList(container,?view,?list,?false);??
???????return?view;??
???}??

所以更多邏輯應該在framework中的LocalePicker.java中。既然是ListFragment，那就必須有Adapter,在此類中有構建了一個Adapter：

/**?
????*?Constructs?an?Adapter?object?containing?Locale?information.?Content?is?sorted?by?
????*?{@link?LocaleInfo#label}.?
????*/??
???public?static?ArrayAdapter<LocaleInfo>?constructAdapter(Context?context)?{??
???????return?constructAdapter(context,?R.layout.locale_picker_item,?R.id.locale);??
???}??
???public?static?ArrayAdapter<LocaleInfo>?constructAdapter(Context?context,??
???????????final?int?layoutId,?final?int?fieldId)?{??
???????boolean?isInDeveloperMode?=?Settings.Global.getInt(context.getContentResolver(),??
???????????????Settings.Global.DEVELOPMENT_SETTINGS_ENABLED,?0)?!=?0;??
???????//獲取系統支持語言的信息??
???????final?List<LocaleInfo>?localeInfos?=?getAllAssetLocales(context,?isInDeveloperMode);??
???????final?LayoutInflater?inflater?=??
???????????????(LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);??
???????return?new?ArrayAdapter<LocaleInfo>(context,?layoutId,?fieldId,?localeInfos)?{??
???????????@Override??
???????????public?View?getView(int?position,?View?convertView,?ViewGroup?parent)?{??
???????????????View?view;??
???????????????TextView?text;??
???????????????if?(convertView?==?null)?{??
???????????????????view?=?inflater.inflate(layoutId,?parent,?false);??
???????????????????text?=?(TextView)?view.findViewById(fieldId);??
???????????????????view.setTag(text);??
???????????????}?else?{??
???????????????????view?=?convertView;??
???????????????????text?=?(TextView)?view.getTag();??
???????????????}??
???????????????LocaleInfo?item?=?getItem(position);??
???????????????text.setText(item.toString());??
???????????????text.setTextLocale(item.getLocale());??
???????????????return?view;??
???????????}??
???????};??
???}??

而此方法通過getAllAssetLocales()方法獲取系統支持語言的信息：

public?static?List<LocaleInfo>?getAllAssetLocales(Context?context,?boolean?isInDeveloperMode)?{??
????????final?Resources?resources?=?context.getResources();??
????????//獲取系統所支持的語言??
????????final?String[]?locales?=?Resources.getSystem().getAssets().getLocales();??
????????List<String>?localeList?=?new?ArrayList<String>(locales.length);??
????????Collections.addAll(localeList,?locales);??
??
????????//?Don't?show?the?pseudolocales?unless?we're?in?developer?mode.???
????????if?(!isInDeveloperMode)?{??
????????????localeList.remove("ar-XB");??
????????????localeList.remove("en-XA");??
????????}??
??
????????Collections.sort(localeList);??
????????final?String[]?specialLocaleCodes?=?resources.getStringArray(R.array.special_locale_codes);??
????????final?String[]?specialLocaleNames?=?resources.getStringArray(R.array.special_locale_names);??
??
????????final?ArrayList<LocaleInfo>?localeInfos?=?new?ArrayList<LocaleInfo>(localeList.size());??
????????for?(String?locale?:?localeList)?{??
????????????final?Locale?l?=?Locale.forLanguageTag(locale.replace('_',?'-'));??
????????????if?(l?==?null?||?"und".equals(l.getLanguage())??
????????????????????||?l.getLanguage().isEmpty()?||?l.getCountry().isEmpty())?{??
????????????????continue;??
????????????}??
??
????????????if?(localeInfos.isEmpty())?{??
????????????????if?(DEBUG)?{??
????????????????????Log.v(TAG,?"adding?initial?"+?toTitleCase(l.getDisplayLanguage(l)));??
????????????????}??
????????????????localeInfos.add(new?LocaleInfo(toTitleCase(l.getDisplayLanguage(l)),?l));??
????????????}?else?{??
????????????????//?check?previous?entry:??
????????????????//??same?lang?and?a?country?->?upgrade?to?full?name?and??
????????????????//????insert?ours?with?full?name??
????????????????//??diff?lang?->?insert?ours?with?lang-only?name??
????????????????final?LocaleInfo?previous?=?localeInfos.get(localeInfos.size()?-?1);??
????????????????if?(previous.locale.getLanguage().equals(l.getLanguage())?&&??
????????????????????????!previous.locale.getLanguage().equals("zz"))?{??
????????????????????if?(DEBUG)?{??
????????????????????????Log.v(TAG,?"backing?up?and?fixing?"?+?previous.label?+?"?to?"?+??
????????????????????????????????getDisplayName(previous.locale,?specialLocaleCodes,?specialLocaleNames));??
????????????????????}??
????????????????????previous.label?=?toTitleCase(getDisplayName(??
????????????????????????????previous.locale,?specialLocaleCodes,?specialLocaleNames));??
????????????????????if?(DEBUG)?{??
????????????????????????Log.v(TAG,?"??and?adding?"+?toTitleCase(??
????????????????????????????????getDisplayName(l,?specialLocaleCodes,?specialLocaleNames)));??
????????????????????}??
????????????????????localeInfos.add(new?LocaleInfo(toTitleCase(??
????????????????????????????getDisplayName(l,?specialLocaleCodes,?specialLocaleNames)),?l));??
????????????????}?else?{??
????????????????????String?displayName?=?toTitleCase(l.getDisplayLanguage(l));??
????????????????????if?(DEBUG)?{??
????????????????????????Log.v(TAG,?"adding?"+displayName);??
????????????????????}??
????????????????????localeInfos.add(new?LocaleInfo(displayName,?l));??
????????????????}??
????????????}??
????????}??
??
????????Collections.sort(localeInfos);??
????????return?localeInfos;??
????}??

此方法中還會通過Resources.getSystem().getAssets().getLocales()去獲得系統支持的語言信息，然后添加LocaleInfo里邊，再通過Adapter適配到ListView中。getLocales()方法屬于類AssetManager.java：

/**?
?????*?Get?the?locales?that?this?asset?manager?contains?data?for.?
?????*?
?????*?<p>On?SDK?21?(Android?5.0:?Lollipop)?and?above,?Locale?strings?are?valid?
?????*?<a?href="https://tools.ietf.org/html/bcp47">BCP-47</a>?language?tags?and?can?be?
?????*?parsed?using?{@link?java.util.Locale#forLanguageTag(String)}.?
?????*?
?????*?<p>On?SDK?20?(Android?4.4W:?Kitkat?for?watches)?and?below,?locale?strings?
?????*?are?of?the?form?{@code?ll_CC}?where?{@code?ll}?is?a?two?letter?language?code,?
?????*?and?{@code?CC}?is?a?two?letter?country?code.?
?????*/??
????public?native?final?String[]?getLocales();??

乍一看，是個native方法，那不就是跟JNI有關系了，所以只能到相應JNI目錄下去找了，路徑：android5.1\frameworks\base\core\jni，對應文件：android_util_AssetManager.cpp（瀏覽下這個文件，發現這個家伙有點不得了啊，什么resource，theme等都跟它有關系,看樣子還的加油學學JNI啊!），然后找到對應的native方法：

static?jobjectArray?android_content_AssetManager_getLocales(JNIEnv*?env,?jobject?clazz)??
{??
????Vector<String8>?locales;??
??
????AssetManager*?am?=?assetManagerForJavaObject(env,?clazz);??
????if?(am?==?NULL)?{??
????????return?NULL;??
????}??
??
????am->getLocales(&locales);??
??
????const?int?N?=?locales.size();??
??
????jobjectArray?result?=?env->NewObjectArray(N,?g_stringClass,?NULL);??
????if?(result?==?NULL)?{??
????????return?NULL;??
????}??
??
????for?(int?i=0;?i<N;?i++)?{??
????????jstring?str?=?env->NewStringUTF(locales[i].string());??
????????if?(str?==?NULL)?{??
????????????return?NULL;??
????????}??
????????env->SetObjectArrayElement(result,?i,?str);??
????????env->DeleteLocalRef(str);??
????}??
??
????return?result;??
}??

通過上面初步的分析，語言的List界面就基本出來了，在getAllAssetLocales()方法中打了個斷點，查看了下locales被賦值以后的值：

二、語言設置功能實現過程：

上面提到了設置中的LocalePicker類實現了父類接口中的onLocaleSelected()方法：? ?

public?static?interface?LocaleSelectionListener?{??
???????//?You?can?add?any?argument?if?you?really?need?it...??
???????public?void?onLocaleSelected(Locale?locale);??
???}??????
?????
???@Override??
???public?void?onLocaleSelected(final?Locale?locale)?{??
???????if?(Utils.hasMultipleUsers(getActivity()))?{??
???????????mTargetLocale?=?locale;??
???????????showDialog(DLG_SHOW_GLOBAL_WARNING);??
???????}?else?{??
???????????getActivity().onBackPressed();??
???????????LocalePicker.updateLocale(locale);??
???????}??
???}??

此方法中最終調用了其父類的updateLocale()方法來更新系統的語言環境：??

/**?
??*?Requests?the?system?to?update?the?system?locale.?Note?that?the?system?looks?halted?
??*?for?a?while?during?the?Locale?migration,?so?the?caller?need?to?take?care?of?it.?
??*/??
?public?static?void?updateLocale(Locale?locale)?{??
?????try?{??
?????????IActivityManager?am?=?ActivityManagerNative.getDefault();??
?????????Configuration?config?=?am.getConfiguration();??
?????????//?Will?set?userSetLocale?to?indicate?this?isn't?some?passing?default?-?the?user??
?????????//?wants?this?remembered??
?????????config.setLocale(locale);??
?????????am.updateConfiguration(config);??
?????????//?Trigger?the?dirty?bit?for?the?Settings?Provider.??
?????????BackupManager.dataChanged("com.android.providers.settings");??
?????}?catch?(RemoteException?e)?{??
?????????//?Intentionally?left?blank??
?????}??
?}??

又看到ActivityManagerNative.getDefault()，所以可以直接到ActivityManagerService.java中找對應的方法，此方法中先是把選擇的語言設置到Configuration中，記錄下來。設置了不代表系統就知道這檔子事，所以還需要am去更新一下，說的俗氣一點：am老大知道了這檔子事，然后大吼一聲，我這里有個東西改變了，小伙伴們刷新一下！在ActivityManagerService中找到updateConfiguration()方法：

public?void?updateConfiguration(Configuration?values)?{??
????????enforceCallingPermission(android.Manifest.permission.CHANGE_CONFIGURATION,??
????????????????"updateConfiguration()");??
????????synchronized(this)?{??
????????????if?(values?==?null?&&?mWindowManager?!=?null)?{??
????????????????//?sentinel:?fetch?the?current?configuration?from?the?window?manager??
????????????????values?=?mWindowManager.computeNewConfiguration();??
????????????}??
????????????if?(mWindowManager?!=?null)?{??
????????????????mProcessList.applyDisplaySize(mWindowManager);??
????????????}??
????????????final?long?origId?=?Binder.clearCallingIdentity();??
????????????if?(values?!=?null)?{??
????????????????Settings.System.clearConfiguration(values);??
????????????}??
????????????updateConfigurationLocked(values,?null,?false,?false);??
????????????Binder.restoreCallingIdentity(origId);??
????????}??
????}??

看到Settings.System.clearConfiguration(values)不要以為這里把values清除了額，其實這個方法只是把系統字體的特效清除了，比如字體的大小：? ?

/**?
?????????*?@hide?Erase?the?fields?in?the?Configuration?that?should?be?applied?
?????????*?by?the?settings.?
?????????*/??
????????public?static?void?clearConfiguration(Configuration?inoutConfig)?{??
????????????inoutConfig.fontScale?=?0;??
????????}??

然后調用updateConfigurationLocked()方法：

/**?
?????*?Do?either?or?both?things:?(1)?change?the?current?configuration,?and?(2)?
?????*?make?sure?the?given?activity?is?running?with?the?(now)?current?
?????*?configuration.??Returns?true?if?the?activity?has?been?left?running,?or?
?????*?false?if?<var>starting</var>?is?being?destroyed?to?match?the?new?
?????*?configuration.?
?????*?@param?persistent?TODO?
?????*/??
boolean?updateConfigurationLocked(Configuration?values,??
????????????ActivityRecord?starting,?boolean?persistent,?boolean?initLocale)?{??
????????int?changes?=?0;??
????????if?(values?!=?null)?{??
????????????Configuration?newConfig?=?new?Configuration(mConfiguration);??
????????????changes?=?newConfig.updateFrom(values);??
????????????if?(changes?!=?0)?{??
????????????????if?(DEBUG_SWITCH?||?DEBUG_CONFIGURATION)?{??
????????????????????Slog.i(TAG,?"Updating?configuration?to:?"?+?values);??
????????????????}??
?????????????????
????????????????EventLog.writeEvent(EventLogTags.CONFIGURATION_CHANGED,?changes);??
????????????????if?(values.locale?!=?null?&&?!initLocale)?{??
????????????????????saveLocaleLocked(values.locale,??
?????????????????????????????????????!values.locale.equals(mConfiguration.locale),??
?????????????????????????????????????values.userSetLocale);??
????????????????}??
????????????????mConfigurationSeq++;??
????????????????if?(mConfigurationSeq?<=?0)?{??
????????????????????mConfigurationSeq?=?1;??
????????????????}??
????????????????newConfig.seq?=?mConfigurationSeq;??
????????????????mConfiguration?=?newConfig;??
????????????????Slog.i(TAG,?"Config?changes="?+?Integer.toHexString(changes)?+?"?"?+?newConfig);??
????????????????mUsageStatsService.reportConfigurationChange(newConfig,?mCurrentUserId);??
????????????????//mUsageStatsService.noteStartConfig(newConfig);??
????????????????final?Configuration?configCopy?=?new?Configuration(mConfiguration);??
?????????????????
????????????????//?TODO:?If?our?config?changes,?should?we?auto?dismiss?any?currently??
????????????????//?showing?dialogs???
????????????????mShowDialogs?=?shouldShowDialogs(newConfig);??
????????????????AttributeCache?ac?=?AttributeCache.instance();??
????????????????if?(ac?!=?null)?{??
????????????????????ac.updateConfiguration(configCopy);??
????????????????}??
????????????????//?Make?sure?all?resources?in?our?process?are?updated??
????????????????//?right?now,?so?that?anyone?who?is?going?to?retrieve??
????????????????//?resource?values?after?we?return?will?be?sure?to?get??
????????????????//?the?new?ones.??This?is?especially?important?during??
????????????????//?boot,?where?the?first?config?change?needs?to?guarantee??
????????????????//?all?resources?have?that?config?before?following?boot??
????????????????//?code?is?executed.??
????????????????mSystemThread.applyConfigurationToResources(configCopy);??
????????????????if?(persistent?&&?Settings.System.hasInterestingConfigurationChanges(changes))?{??
????????????????????Message?msg?=?mHandler.obtainMessage(UPDATE_CONFIGURATION_MSG);??
????????????????????msg.obj?=?new?Configuration(configCopy);??
????????????????????mHandler.sendMessage(msg);??
????????????????}??
????????????????for?(int?i=mLruProcesses.size()-1;?i>=0;?i--)?{??
????????????????????ProcessRecord?app?=?mLruProcesses.get(i);??
????????????????????try?{??
????????????????????????if?(app.thread?!=?null)?{??
????????????????????????????if?(DEBUG_CONFIGURATION)?Slog.v(TAG,?"Sending?to?proc?"??
????????????????????????????????????+?app.processName?+?"?new?config?"?+?mConfiguration);??
????????????????????????????app.thread.scheduleConfigurationChanged(configCopy);??
????????????????????????}??
????????????????????}?catch?(Exception?e)?{??
????????????????????}??
????????????????}??
????????????????Intent?intent?=?new?Intent(Intent.ACTION_CONFIGURATION_CHANGED);??
????????????????intent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY??
????????????????????????|?Intent.FLAG_RECEIVER_REPLACE_PENDING??
????????????????????????|?Intent.FLAG_RECEIVER_FOREGROUND);??
????????????????broadcastIntentLocked(null,?null,?intent,?null,?null,?0,?null,?null,??
????????????????????????null,?AppOpsManager.OP_NONE,?false,?false,?MY_PID,??
????????????????????????Process.SYSTEM_UID,?UserHandle.USER_ALL);??
????????????????if?((changes&ActivityInfo.CONFIG_LOCALE)?!=?0)?{??
????????????????????intent?=?new?Intent(Intent.ACTION_LOCALE_CHANGED);??
????????????????????intent.addFlags(Intent.FLAG_RECEIVER_FOREGROUND);??
????????????????????broadcastIntentLocked(null,?null,?intent,??
????????????????????????????null,?null,?0,?null,?null,?null,?AppOpsManager.OP_NONE,??
????????????????????????????false,?false,?MY_PID,?Process.SYSTEM_UID,?UserHandle.USER_ALL);??
????????????????}??
????????????}??
????????}??
????????boolean?kept?=?true;??
????????final?ActivityStack?mainStack?=?mStackSupervisor.getFocusedStack();??
????????//?mainStack?is?null?during?startup.??
????????if?(mainStack?!=?null)?{??
????????????if?(changes?!=?0?&&?starting?==?null)?{??
????????????????//?If?the?configuration?changed,?and?the?caller?is?not?already??
????????????????//?in?the?process?of?starting?an?activity,?then?find?the?top??
????????????????//?activity?to?check?if?its?configuration?needs?to?change.??
????????????????starting?=?mainStack.topRunningActivityLocked(null);??
????????????}??
????????????if?(starting?!=?null)?{??
????????????????kept?=?mainStack.ensureActivityConfigurationLocked(starting,?changes);??
????????????????//?And?we?need?to?make?sure?at?this?point?that?all?other?activities??
????????????????//?are?made?visible?with?the?correct?configuration.??
????????????????mStackSupervisor.ensureActivitiesVisibleLocked(starting,?changes);??
????????????}??
????????}??
????????if?(values?!=?null?&&?mWindowManager?!=?null)?{??
????????????mWindowManager.setNewConfiguration(mConfiguration);??
????????}??
????????return?kept;??
????}??

此方法主要做兩件事：第一，改變當前的configuration，將新的數據放進去。第二，保證正在運行的應用程序界面更新最新的configuration。先調用updateFrom()方法，遍歷configuration包含的屬性是否改變，如果有改變就返回一個對應的整數，如果沒有改變就返回0。就語言改變而言，根據上面的分析，configuration至少有3個屬性發生了改變：fontscale（之前沒有設置字體的效果就不會改變）、locale和布局的direction。

有了新的數據就要保存，保存在configuration中不是個事。對于Android系統而言，改變語言，有兩個地方的數據需要更新，一個是SystemProperties，另一個是數據庫。前者以鍵值對的形式存放數據，多用于System，后者保存于DataBase中，多用于應用程序獲取，算是對外開放的數據。上面方法中對這兩個地方都進行了數據保存操作:

1)SystemProperties：調用saveLocaleLocked()方法：

/**?
?????*?Save?the?locale.??You?must?be?inside?a?synchronized?(this)?block.?
?????*/??
????private?void?saveLocaleLocked(Locale?l,?boolean?isDiff,?boolean?isPersist)?{??
????????if(isDiff)?{??
????????????SystemProperties.set("user.language",?l.getLanguage());??
????????????SystemProperties.set("user.region",?l.getCountry());??
????????}??
????????if(isPersist)?{??
????????????SystemProperties.set("persist.sys.language",?l.getLanguage());??
????????????SystemProperties.set("persist.sys.country",?l.getCountry());??
????????????SystemProperties.set("persist.sys.localevar",?l.getVariant());??
????????????mHandler.sendMessage(mHandler.obtainMessage(SEND_LOCALE_TO_MOUNT_DAEMON_MSG,?l));??
????????}??
????}??

2)database:調用Settings.System.putConfiguration()方法：

if?(persistent?&&?Settings.System.hasInterestingConfigurationChanges(changes))?{??
???????????????????Message?msg?=?mHandler.obtainMessage(UPDATE_CONFIGURATION_MSG);??
???????????????????msg.obj?=?new?Configuration(configCopy);??
???????????????????mHandler.sendMessage(msg);??
???}??
???...??
???case?UPDATE_CONFIGURATION_MSG:?{??
???????????????final?ContentResolver?resolver?=?mContext.getContentResolver();??
???????????????Settings.System.putConfiguration(resolver,?(Configuration)msg.obj);??
???????????}?break;??

該保存的數據保存了，但是Resource還不知道這檔子事，因為Android代碼和資源是分開的，Resource不知道Configuration發生了變化，Resource就不會去加載正確的資源。所以接下來此方法調用了mSystemThread.applyConfigurationToResources(configCopy)來完成這件事，mSystemThread是一個ActivityThread對象，其初始化在ActivityManagerService的構造函數中完成：? ?

mSystemThread?=?ActivityThread.currentActivityThread();??

//此方法屬于ActivityThread??
????public?final?void?applyConfigurationToResources(Configuration?config)?{??
????????synchronized?(mResourcesManager)?{??
????????????mResourcesManager.applyConfigurationToResourcesLocked(config,?null);??
????????}??
????}??
????//此方法屬于ResourcesManage??
????public?final?boolean?applyConfigurationToResourcesLocked(Configuration?config,??
????????????CompatibilityInfo?compat)?{??
????????if?(mResConfiguration?==?null)?{??
????????????mResConfiguration?=?new?Configuration();??
????????}??
????????if?(!mResConfiguration.isOtherSeqNewer(config)?&&?compat?==?null)?{??
????????????if?(DEBUG_CONFIGURATION)?Slog.v(TAG,?"Skipping?new?config:?curSeq="??
????????????????????+?mResConfiguration.seq?+?",?newSeq="?+?config.seq);??
????????????return?false;??
????????}??
????????int?changes?=?mResConfiguration.updateFrom(config);??
????????flushDisplayMetricsLocked();??
????????DisplayMetrics?defaultDisplayMetrics?=?getDisplayMetricsLocked(Display.DEFAULT_DISPLAY);??
????????if?(compat?!=?null?&&?(mResCompatibilityInfo?==?null?||??
????????????????!mResCompatibilityInfo.equals(compat)))?{??
????????????mResCompatibilityInfo?=?compat;??
????????????changes?|=?ActivityInfo.CONFIG_SCREEN_LAYOUT??
????????????????????|?ActivityInfo.CONFIG_SCREEN_SIZE??
????????????????????|?ActivityInfo.CONFIG_SMALLEST_SCREEN_SIZE;??
????????}??
????????//?set?it?for?java,?this?also?affects?newly?created?Resources??
????????if?(config.locale?!=?null)?{??
????????????Locale.setDefault(config.locale);??
????????}??
????????Resources.updateSystemConfiguration(config,?defaultDisplayMetrics,?compat);??
????????ApplicationPackageManager.configurationChanged();??
????????//Slog.i(TAG,?"Configuration?changed?in?"?+?currentPackageName());??
????????Configuration?tmpConfig?=?null;??
????????for?(int?i=mActiveResources.size()-1;?i>=0;?i--)?{??
????????????ResourcesKey?key?=?mActiveResources.keyAt(i);??
????????????Resources?r?=?mActiveResources.valueAt(i).get();??
????????????if?(r?!=?null)?{??
????????????????if?(DEBUG_CONFIGURATION)?Slog.v(TAG,?"Changing?resources?"??
????????????????????????+?r?+?"?config?to:?"?+?config);??
????????????????int?displayId?=?key.mDisplayId;??
????????????????boolean?isDefaultDisplay?=?(displayId?==?Display.DEFAULT_DISPLAY);??
????????????????DisplayMetrics?dm?=?defaultDisplayMetrics;??
????????????????final?boolean?hasOverrideConfiguration?=?key.hasOverrideConfiguration();??
????????????????if?(!isDefaultDisplay?||?hasOverrideConfiguration)?{??
????????????????????if?(tmpConfig?==?null)?{??
????????????????????????tmpConfig?=?new?Configuration();??
????????????????????}??
????????????????????tmpConfig.setTo(config);??
????????????????????if?(!isDefaultDisplay)?{??
????????????????????????dm?=?getDisplayMetricsLocked(displayId);??
????????????????????????applyNonDefaultDisplayMetricsToConfigurationLocked(dm,?tmpConfig);??
????????????????????}??
????????????????????if?(hasOverrideConfiguration)?{??
????????????????????????tmpConfig.updateFrom(key.mOverrideConfiguration);??
????????????????????}??
????????????????????r.updateConfiguration(tmpConfig,?dm,?compat);??
????????????????}?else?{??
????????????????????r.updateConfiguration(config,?dm,?compat);??
????????????????}??
????????????????//Slog.i(TAG,?"Updated?app?resources?"?+?v.getKey()??
????????????????//????????+?"?"?+?r?+?":?"?+?r.getConfiguration());??
????????????}?else?{??
????????????????//Slog.i(TAG,?"Removing?old?resources?"?+?v.getKey());??
????????????????mActiveResources.removeAt(i);??
????????????}??
????????}??
????????return?changes?!=?0;??
????}??

此方法中Resource和ApplicationPackageManager都會去更新configuration，configuration所包含的屬性都會遍歷到，該更新的數據更新，該清除的緩存清除。

到這里，第一件事算是做完了，就要做第二件事，讓新的configuration更新到所有界面，updateConfigurationLocked()方法通過遍歷保存在ProcessRecord中的進程，然后通過scheduleConfigurationChanged()方法更新它們的configuration：

for?(int?i=mLruProcesses.size()-1;?i>=0;?i--)?{??
?????ProcessRecord?app?=?mLruProcesses.get(i);??
?????try?{??
??????????if?(app.thread?!=?null)?{??
??????????if?(DEBUG_CONFIGURATION)?Slog.v(TAG,?"Sending?to?proc?"??
????????????????????????????????????+?app.processName?+?"?new?config?"?+?mConfiguration);??
???????????app.thread.scheduleConfigurationChanged(configCopy);??
?????????}??
?????}?catch?(Exception?e)?{??
?????}??
?}??

此處通過Binder機制調用ApplicationThreadNative.java中的scheduleConfigurationChanged()方法，最后調用到ActivityThread中的內部類ApplicationThread的scheduleConfigurationChanged()方法，函數調用堆棧如圖：

public?void?scheduleConfigurationChanged(Configuration?config)?{??
????????????updatePendingConfiguration(config);??
????????????sendMessage(H.CONFIGURATION_CHANGED,?config);??
????}??

case?CONFIGURATION_CHANGED:??
????????????????????Trace.traceBegin(Trace.TRACE_TAG_ACTIVITY_MANAGER,?"configChanged");??
????????????????????mCurDefaultDisplayDpi?=?((Configuration)msg.obj).densityDpi;??
????????????????????handleConfigurationChanged((Configuration)msg.obj,?null);??
????????????????????Trace.traceEnd(Trace.TRACE_TAG_ACTIVITY_MANAGER);??
????????????????????break;??

final?void?handleConfigurationChanged(Configuration?config,?CompatibilityInfo?compat)?{??
????????int?configDiff?=?0;??
????????synchronized?(mResourcesManager)?{??
????????????if?(mPendingConfiguration?!=?null)?{??
????????????????if?(!mPendingConfiguration.isOtherSeqNewer(config))?{??
????????????????????config?=?mPendingConfiguration;??
????????????????????mCurDefaultDisplayDpi?=?config.densityDpi;??
????????????????????updateDefaultDensity();??
????????????????}??
????????????????mPendingConfiguration?=?null;??
????????????}??
????????????if?(config?==?null)?{??
????????????????return;??
????????????}??
?????????????
????????????if?(DEBUG_CONFIGURATION)?Slog.v(TAG,?"Handle?configuration?changed:?"??
????????????????????+?config);??
????????????mResourcesManager.applyConfigurationToResourcesLocked(config,?compat);??
????????????if?(mConfiguration?==?null)?{??
????????????????mConfiguration?=?new?Configuration();??
????????????}??
????????????if?(!mConfiguration.isOtherSeqNewer(config)?&&?compat?==?null)?{??
????????????????return;??
????????????}??
????????????configDiff?=?mConfiguration.diff(config);??
????????????mConfiguration.updateFrom(config);??
????????????config?=?applyCompatConfiguration(mCurDefaultDisplayDpi);??
????????}??
????????ArrayList<ComponentCallbacks2>?callbacks?=?collectComponentCallbacks(false,?config);??
????????freeTextLayoutCachesIfNeeded(configDiff);??
????????if?(callbacks?!=?null)?{??
????????????final?int?N?=?callbacks.size();??
????????????for?(int?i=0;?i<N;?i++)?{??
????????????????performConfigurationChanged(callbacks.get(i),?config);??
????????????}??
????????}??
????}??

到這里設置語言以后，代碼跑的流程就基本結束了，需要一提的是performConfigurationChanged()方法。為什么要提它呢？因為有時候寫應用的時候activity需要關注一些configChanged，如：android:configChanges="orientation|keyboardHidden|screenSize"，然后重寫onConfigurationChanged()方法。然而觸發這個方法回調的觸發點在哪里呢？這里就以設置語言為例，設置語言觸發了configuration的改變。先來看下performConfigurationChanged()方法：? ??

private?static?void?performConfigurationChanged(ComponentCallbacks2?cb,?Configuration?config)?{??
????????//?Only?for?Activity?objects,?check?that?they?actually?call?up?to?their??
????????//?superclass?implementation.??ComponentCallbacks2?is?an?interface,?so??
????????//?we?check?the?runtime?type?and?act?accordingly.??
????????Activity?activity?=?(cb?instanceof?Activity)???(Activity)?cb?:?null;??
????????if?(activity?!=?null)?{??
????????????activity.mCalled?=?false;??
????????}??
????????boolean?shouldChangeConfig?=?false;??
????????if?((activity?==?null)?||?(activity.mCurrentConfig?==?null))?{??
????????????shouldChangeConfig?=?true;??
????????}?else?{??
????????????//?If?the?new?config?is?the?same?as?the?config?this?Activity??
????????????//?is?already?running?with?then?don't?bother?calling??
????????????//?onConfigurationChanged??
????????????int?diff?=?activity.mCurrentConfig.diff(config);??
????????????if?(diff?!=?0)?{??
????????????????//?If?this?activity?doesn't?handle?any?of?the?config?changes??
????????????????//?then?don't?bother?calling?onConfigurationChanged?as?we're??
????????????????//?going?to?destroy?it.??
????????????????if?((~activity.mActivityInfo.getRealConfigChanged()?&?diff)?==?0)?{??
????????????????????shouldChangeConfig?=?true;??
????????????????}??
????????????}??
????????}??
????????if?(DEBUG_CONFIGURATION)?Slog.v(TAG,?"Config?callback?"?+?cb??
????????????????+?":?shouldChangeConfig="?+?shouldChangeConfig);??
????????if?(shouldChangeConfig)?{??
????????????cb.onConfigurationChanged(config);??
????????????if?(activity?!=?null)?{??
????????????????if?(!activity.mCalled)?{??
????????????????????throw?new?SuperNotCalledException(??
????????????????????????????"Activity?"?+?activity.getLocalClassName()?+??
????????????????????????"?did?not?call?through?to?super.onConfigurationChanged()");??
????????????????}??
????????????????activity.mConfigChangeFlags?=?0;??
????????????????activity.mCurrentConfig?=?new?Configuration(config);??
????????????}??
????????}??
????}??

如果configuration確實改變了，那么此方法中就會調用cb.onConfigurationChanged(config)。cb代表ComponentCallbacks2，而ComponentCallbacks2 又繼承于ComponentCallbacks，所以onConfigurationChanged()方法屬于ComponentCallbacks，同樣Activity類也實現了ComponentCallbacks2這個接口，如此一來這個回調的過程就連接上了。也充分說明了為什么在configuration改變以后，activity關注的config會回調其父類的onConfigurationChanged()方法。

最后就是廣播configuration改變了，updateConfigurationLocked()廣播了ACTION_CONFIGURATION_CHANGED和ACTION_LOCALE_CHANGED，使用的方法是broadcastIntentLocked()，此方法廣播成功返回BROADCAST_SUCCESS。具體就不多說了。