以前了解Android的多语言实现很简单，可以在不同的语言环境下使用不同的资源，就做好相应的语言适配就好，但是一直没有实际使用过。 最近公司的项目要用到多国语言切换，并且还是和手机上系统设置里面的语言切换功能一样，于是就上网查了下资料。一般都是在应用类实现多国语言切换，这个是很简单。而我想切换整个系统的语言。由于谷歌没有把系统设置里面的接口给开放出来，所以就只好去查看它的源码了~
android语言切换是在：
packages/apps/Settings/com/android/settings/LocalePicker.java
的updateLocale()函数中调用，源码如下：
/** * 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(); config.locale = locale; // indicate this isn't some passing default - the user wants this remembered config.userSetLocale = true; am.updateConfiguration(config); // Trigger the dirty bit for the Settings Provider. BackupManager.dataChanged("com.android.providers.settings"); } catch (RemoteException e) { // Intentionally left blank } }
从注释可以看出, 只要本地local改变就会调用该函数. 查看ActivityManagerNative的getDefault()可以看到, 该函数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updateConfiguration()函数.
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 = puteNewConfiguration(); } 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); } }
该函数, 首先进行的是权限的校验. 然后调用updateConfigurationLocked()函数.
/** * 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 */ public boolean updateConfigurationLocked(Configuration values, ActivityRecord starting, boolean persistent, boolean initLocale) { int changes = 0; boolean kept = true; 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, values.simSetLocale); } mConfigurationSeq++; if (mConfigurationSeq <= 0) { mConfigurationSeq = 1; } newConfig.seq = mConfigurationSeq; mConfiguration = newConfig; Slog.i(TAG, "Config changed: " + newConfig); final Configuration configCopy = new Configuration(mConfiguration); 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); broadcastIntentLocked(null, null, intent, null, null, 0, null, null, null, false, false, MY_PID, Process.SYSTEM_UID); if ((changes&ActivityInfo.CONFIG_LOCALE) != 0) { broadcastIntentLocked(null, null, new Intent(Intent.ACTION_LOCALE_CHANGED), null, null, 0, null, null, null, false, false, MY_PID, Process.SYSTEM_UID); } } } 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 = mMainStack.topRunningActivityLocked(null); } if (starting != null) { kept = mMainStack.ensureActivityConfigurationLocked(starting, changes); // And we need to make sure at this point that all other activities // are made visible with the correct configuration. mMainStack.ensureActivitiesVisibleLocked(starting, changes); } if (values != null && mWindowManager != null) { mWindowManager.setNewConfiguration(mConfiguration); } return kept; }
整个语言切换就在这个函数中完成. 咋一看似乎没感觉到该函数做了哪些事情. 我们首先来看注释: 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。
/** * Copy the fields from delta into this Configuration object, keeping * track of which ones have changed. Any undefined fields in * <var>delta</var> are ignored and not copied in to the current * Configuration. * @return Returns a bit mask of the changed fields, as per * {@link #diff}. */ public int updateFrom(Configuration delta) { int changed = 0; ... if (delta.locale != null && (locale == null || !locale.equals(delta.locale))) { changed |= ActivityInfo.CONFIG_LOCALE; locale = delta.locale != null ? (Locale) delta.locale.clone() : null; textLayoutDirection = LocaleUtil.getLayoutDirectionFromLocale(locale); } if (delta.userSetLocale && (!userSetLocale || ((changed & ActivityInfo.CONFIG_LOCALE) != 0))) { userSetLocale = true; changed |= ActivityInfo.CONFIG_LOCALE; } ... return changed; }
因为语言改变了, 那么 (!locale.equals(delta.locale)) 是true. changed 大于0, 然后return changed. 回到ActivityManagerService.java的updateConfigurationLocked函数, 因为changed不为0 , 所以走if这个流程. 继续看代码。
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) { } }
首先看到的是mLurProcesses 是ArrayList类型. LRU : Least Recently Used保存所有运行过的进程. ProcessRecord进程类, 一个apk文件运行时会对应一个进程. app.thread. 此处的thread代表的是ApplicationThreadNative.java类型. 然后调用其scheduleConfigurationChanged(); 查看该函数。
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(); }
又是通过binder调用, 所以 , binder在android中是一个很重要的概念. 此处远程调用的是ActivityThread.java中的私有内部内ApplicationThread。
private class ApplicationThread extends ApplicationThreadNative { private static final String HEAP_COLUMN = "%13s %8s %8s %8s %8s %8s %8s"; private static final String ONE_COUNT_COLUMN = "%21s %8d"; private static final String TWO_COUNT_COLUMNS = "%21s %8d %21s %8d"; private static final String TWO_COUNT_COLUMNS_DB = "%21s %8d %21s %8d"; private static final String DB_INFO_FORMAT = " %8s %8s %14s %14s %s"; ... public void scheduleConfigurationChanged(Configuration config) { updatePendingConfiguration(config); queueOrSendMessage(H.CONFIGURATION_CHANGED, config); } ... }
而ApplicationThread中的handler的CONFIGURATION_CHANGED是调用handleConfigurationChanged()。
final void handleConfigurationChanged(Configuration config, CompatibilityInfo compat) { ArrayList<ComponentCallbacks2> callbacks = null; ... ... applyConfigurationToResourcesLocked(config, compat); ... callbacks = collectComponentCallbacksLocked(false, config); ... if (callbacks != null) { final int N = callbacks.size(); for (int i=0; i<N; i++) { performConfigurationChanged(callbacks.get(i), config); } }
这个函数首先是调用applyConfigurationToResourcesLocked(). 看函数名大概可以猜想到: 将configuration应用到resources.这里configuration改变的是local 本地语言. 那而resources资源包含语言包吗？
final boolean applyConfigurationToResourcesLocked(Configuration config, CompatibilityInfo compat) { int changes = mResConfiguration.updateFrom(config); DisplayMetrics dm = getDisplayMetricsLocked(null, true); if (compat != null && (mResCompatibilityInfo == null || !mResCompatibilityInfo.equals(compat))) { mResCompatibilityInfo = compat; changes |= ActivityInfo.CONFIG_SCREEN_LAYOUT | ActivityInfo.CONFIG_SCREEN_SIZE | ActivityInfo.CONFIG_SMALLEST_SCREEN_SIZE; } ... Resources.updateSystemConfiguration(config, dm, compat); ... Iterator<WeakReference<Resources>> it = mActiveResources.values().iterator(); while (it.hasNext()) { WeakReference<Resources> v = it.next(); Resources r = v.get(); if (r != null) { if (DEBUG_CONFIGURATION) Slog.v(TAG, "Changing resources " + r + " config to: " + config); 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()); it.remove(); } } return changes != 0; }
Resources.updateSystemConfiguration()清除一部分系统资源, 并且将config更新到Resources, 而Resources包含了一个AssetManager对象, 该对象的核心实现是在AssetManager.cpp中完成的. 然后循环清空mActivityResources资源. 再回到handleConfigurationChanged()函数, 执行完updateSystemConfiguration后, 会循环该进程的所有activity:
if (callbacks != null) { final int N = callbacks.size();for (int i=0; i<N; i++) {performConfigurationChanged(callbacks.get(i), config);}}
再来看performConfigurationChanged的实现:
private final 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); } } }
该函数判断configuration是否改变, 如果改变那么shouldChangeConfig为true. 然后调用activity的onConfigurationChange(config);
/** * Called by the system when the device configuration changes while your * activity is running. Note that this will <em>only</em> be called if * you have selected configurations you would like to handle with the * {@link android.R.attr#configChanges} attribute in your manifest. If * any configuration change occurs that is not selected to be reported * by that attribute, then instead of reporting it the system will stop * and restart the activity (to have it launched with the new * configuration). * * <p>At the time that this function has been called, your Resources * object will have been updated to return resource values matching the * new configuration. * * @param newConfig The new device configuration. */ public void onConfigurationChanged(Configuration newConfig) { mCalled = true; mFragments.dispatchConfigurationChanged(newConfig); if (mWindow != null) { // Pass the configuration changed event to the window mWindow.onConfigurationChanged(newConfig); } if (mActionBar != null) { // Do this last; the action bar will need to access // view changes from above. mActionBar.onConfigurationChanged(newConfig); } }
查看注释, 大概意思是: 如果你的activity运行 , 设备信息有改变(即configuration改变)时由系统调用. 如果你在manifest.xml中配置了configChnages属性则表示有你自己来处理configuration change. 否则就重启当前这个activity. 而重启之前, 旧的resources已经被清空, 那么就会装载新的资源, 整个过程就完成了语言切换后 , 能够让所有app使用新的语言。
上面这些就是对Android 系统里面的语言切换进行了源码分析，就先分析到这里；有些东西我也不是很看懂，能力有限~
原文地址：/article/android-language-switch.html
