打开本地路径：D:\android\sdk\sources\android-26\com\android\internal\app，其中类LocalePicker的updateLocales(LocaleList locales) 方法便是系统切换语言的入口：
/**
* 请求系统更新locale列表，开发者需要注意的是，当切换locale时系统看起来会停顿一下
*/
public static void updateLocales(LocaleList locales) {
try {
final IActivityManager am = ActivityManager.getService();
final Configuration config = am.getConfiguration();
config.setLocales(locales);
config.userSetLocale = true;
am.updatePersistentConfiguration(config);
// Trigger the dirty bit for the Settings Provider.
BackupManager.dataChanged("com.android.providers.settings");
} catch (RemoteException e) {
// Intentionally left blank
}
}
只要本地locale改变便会调用该方法。ActivityManager.getService()可以看到, 该方法返回的是远程服务对象ActivityManagerServices.java在本地的一个代理，最终调用的是ActivityManagerService.java中的updatePersistentConfiguration()方法。
@Override
public void updatePersistentConfiguration(Configuration values) {
enforceCallingPermission(CHANGE_CONFIGURATION, "updatePersistentConfiguration()");
enforceWriteSettingsPermission("updatePersistentConfiguration()");
if (values == null) {
throw new NullPointerException("Configuration must not be null");
}
int userId = UserHandle.getCallingUserId();
synchronized(this) {
updatePersistentConfigurationLocked(values, userId);
}
}
这个方法首先进行权限的验证，然后调用updatePersistentConfigurationLocked方法。
private void updatePersistentConfigurationLocked(Configuration values, @UserIdInt int userId) {
final long origId = Binder.clearCallingIdentity();
try {
updateConfigurationLocked(values, null, false, true, userId, false /* deferResume */);
} finally {
Binder.restoreCallingIdentity(origId);
}
}
private boolean updateConfigurationLocked(Configuration values, ActivityRecord starting,
boolean initLocale, boolean persistent, int userId, boolean deferResume) {
return updateConfigurationLocked(values, starting, initLocale, persistent, userId,
deferResume, null /* result */);
}
/**
* 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 userId is only used when persistent parameter is set to true to persist configuration
* for that particular user
*/
private boolean updateConfigurationLocked(Configuration values, ActivityRecord starting,
boolean initLocale, boolean persistent, int userId, boolean deferResume,
UpdateConfigurationResult result) {
int changes = 0;
boolean kept = true;
if (mWindowManager != null) {
mWindowManager.deferSurfaceLayout();
}
try {
if (values != null) {
changes = updateGlobalConfiguration(values, initLocale, persistent, userId,
deferResume);
}
kept = ensureConfigAndVisibilityAfterUpdate(starting, changes);
} finally {
if (mWindowManager != null) {
mWindowManager.continueSurfaceLayout();
}
}
if (result != null) {
result.changes = changes;
result.activityRelaunched = !kept;
}
return kept;
}
由方法注释开始看起：Do either or both things: (1) change the current configuration, and (2)
make sure the given activity is running with the (now) current. configuration大概意思是: 这个函数做了两件事情. (1). 改变当前的configuration. 意思就是让改变的configuration更新到当前configuration. (2) 确保所有正在运行的activity都能更新改变后的configuration.(这点是关键.) . 我们按照这个思路看看android是如何更新configuration. 查看代码
, 首先看到 这个函数首先判断values是否为空, 这里values肯定不为空的, 然后changes = newConfig.updateFrom(values); 我们看看updateFrom做了什么操作
/** Update default (global) configuration and notify listeners about changes. */
private int updateGlobalConfiguration(@NonNull Configuration values, boolean initLocale,
boolean persistent, int userId, boolean deferResume) {
mTempConfig.setTo(getGlobalConfiguration());
final int changes = mTempConfig.updateFrom(values);
if (changes == 0) {
// Since calling to Activity.setRequestedOrientation leads to freezing the window with
// setting WindowManagerService.mWaitingForConfig to true, it is important that we call
// performDisplayOverrideConfigUpdate in order to send the new display configuration
// (even if there are no actual changes) to unfreeze the window.
performDisplayOverrideConfigUpdate(values, deferResume, DEFAULT_DISPLAY);
return 0;
}
if (DEBUG_SWITCH || DEBUG_CONFIGURATION) Slog.i(TAG_CONFIGURATION,
"Updating global configuration to: " + values);
EventLog.writeEvent(EventLogTags.CONFIGURATION_CHANGED, changes);
if (!initLocale && !values.getLocales().isEmpty() && values.userSetLocale) {
final LocaleList locales = values.getLocales();
int bestLocaleIndex = 0;
if (locales.size() > 1) {
if (mSupportedSystemLocales == null) {
mSupportedSystemLocales = Resources.getSystem().getAssets().getLocales();
}
bestLocaleIndex = Math.max(0, locales.getFirstMatchIndex(mSupportedSystemLocales));
}
SystemProperties.set("persist.sys.locale",
locales.get(bestLocaleIndex).toLanguageTag());
LocaleList.setDefault(locales, bestLocaleIndex);
mHandler.sendMessage(mHandler.obtainMessage(SEND_LOCALE_TO_MOUNT_DAEMON_MSG,
locales.get(bestLocaleIndex)));
}
mConfigurationSeq = Math.max(++mConfigurationSeq, 1);
mTempConfig.seq = mConfigurationSeq;
// Update stored global config and notify everyone about the change.
mStackSupervisor.onConfigurationChanged(mTempConfig);
Slog.i(TAG, "Config changes=" + Integer.toHexString(changes) + " " + mTempConfig);
// TODO(multi-display): Update UsageEvents#Event to include displayId.
mUsageStatsService.reportConfigurationChange(mTempConfig,
mUserController.getCurrentUserIdLocked());
// TODO: If our config changes, should we auto dismiss any currently showing dialogs?
mShowDialogs = shouldShowDialogs(mTempConfig);
AttributeCache ac = AttributeCache.instance();
if (ac != null) {
ac.updateConfiguration(mTempConfig);
}
// 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(mTempConfig);
// We need another copy of global config because we're scheduling some calls instead of
// running them in place. We need to be sure that object we send will be handled unchanged.
final Configuration configCopy = new Configuration(mTempConfig);
if (persistent && Settings.System.hasInterestingConfigurationChanges(changes)) {
Message msg = mHandler.obtainMessage(UPDATE_CONFIGURATION_MSG);
msg.obj = configCopy;
msg.arg1 = userId;
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_CONFIGURATION, "Sending to proc "
+ app.processName + " new config " + configCopy);
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
| Intent.FLAG_RECEIVER_VISIBLE_TO_INSTANT_APPS);
broadcastIntentLocked(null, null, intent, null, null, 0, null, null, null,
AppOpsManager.OP_NONE, null, false, false, MY_PID, SYSTEM_UID,
UserHandle.USER_ALL);
if ((changes & ActivityInfo.CONFIG_LOCALE) != 0) {
intent = new Intent(Intent.ACTION_LOCALE_CHANGED);
intent.addFlags(Intent.FLAG_RECEIVER_FOREGROUND
| Intent.FLAG_RECEIVER_INCLUDE_BACKGROUND
| Intent.FLAG_RECEIVER_VISIBLE_TO_INSTANT_APPS);
if (initLocale || !mProcessesReady) {
intent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY);
}
broadcastIntentLocked(null, null, intent, null, null, 0, null, null, null,
AppOpsManager.OP_NONE, null, false, false, MY_PID, SYSTEM_UID,
UserHandle.USER_ALL);
}
// Override configuration of the default display duplicates global config, so we need to
// update it also. This will also notify WindowManager about changes.
performDisplayOverrideConfigUpdate(mStackSupervisor.getConfiguration(), deferResume,
DEFAULT_DISPLAY);
return changes;
}
从方法的注释可以知道其作用是更新全局存储的config，并通知相关监听类。
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_CONFIGURATION, "Sending to proc "
+ app.processName + " new config " + configCopy);
app.thread.scheduleConfigurationChanged(configCopy);
}
} catch (Exception e) {
}
}
其中这段代码会遍历程序进程记录，然后调用app.thread.scheduleConfigurationChanged(configCopy);来通知config改变。
app.thread是ApplicationThreadNative类型的，然后调用其scheduleConfigurationChanged()方法。
这里先贴上一段25的源码，效果应该是差不多的吧，哈哈！
public final void scheduleConfigurationChanged(Configuration config)
throws RemoteException {
Parcel data = Parcel.obtain();
data.writeInterfaceToken(IApplicationThread.descriptor);
config.writeToParcel(data, 0);
mRemote.transact(SCHEDULE_CONFIGURATION_CHANGED_TRANSACTION, data, null,
IBinder.FLAG_ONEWAY);
data.recycle();
}
这里采用Binder来做的
未完。。。