Android-语言设置流程分析

Android手机语言切换行为，是通过设置-语言和输入法-语言来改变手机的语言，其实这个功能很少被用户使用。

以Android5.1工程源码为基础,从设置app入手来分析和学习语言切换的过程:

一、语言设置界面：

首先在设置app中找到语言设置这个Preference，目前设置中界面大多都是Fragment，先找到语言和输入法的PreferenceScreen，与其对应的Fragment是InputMethodAndLanguageSettings.java，在其onCreate()方法中，首先是增加语言设置的preference：    

addPreferencesFromResource(R.xml.language_settings);

找到language_settings.xml，可发现如下代码：   

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

于是断定LocalePicker就是语言设置的Fragment，它是ListFragment的子类，继承于framework中LocalePicker,并实现了父类的一个接口，其回调方法是onLocaleSelected()，Locale中文含义大致是语言环境，所以可推测这是设置语言后的一个回调方法，不确定的话，可打断点测试一下。然而此类中并没有关于语言设置界面数据适配的太多逻辑，只是通过父类的方法创建了一个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;
   }

所以更多逻辑应该在framework中的LocalePicker.java中。既然是ListFragment，那就必须有Adapter,在此类中有构建了一个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;
       //获取系统支持语言的信息
       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;
           }
       };
   }

而此方法通过getAllAssetLocales()方法获取系统支持语言的信息：

public static List<LocaleInfo> getAllAssetLocales(Context context, boolean isInDeveloperMode) {
        final Resources resources = context.getResources();
        //获取系统所支持的语言
        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;
    }

此方法中还会通过Resources.getSystem().getAssets().getLocales()去获得系统支持的语言信息，然后添加LocaleInfo里边，再通过Adapter适配到ListView中。getLocales()方法属于类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，是个native方法，那不就是跟JNI有关系了，所以只能到相应JNI目录下去找了，路径：android5.1\frameworks\base\core\jni，对应文件：android_util_AssetManager.cpp（浏览下这个文件，发现这个家伙有点不得了啊，什么resource，theme等都跟它有关系,看样子还的加油学学JNI啊!），然后找到对应的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;
}

通过上面初步的分析，语言的List界面就基本出来了，在getAllAssetLocales()方法中打了个断点，查看了下locales被赋值以后的值：

二、语言设置功能实现过程：

上面提到了设置中的LocalePicker类实现了父类接口中的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);
       }
   }

此方法中最终调用了其父类的updateLocale()方法来更新系统的语言环境：  

/**
  * 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中找对应的方法，此方法中先是把选择的语言设置到Configuration中，记录下来。设置了不代表系统就知道这档子事，所以还需要am去更新一下，说的俗气一点：am老大知道了这档子事，然后大吼一声，我这里有个东西改变了，小伙伴们刷新一下！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)不要以为这里把values清除了额，其实这个方法只是把系统字体的特效清除了，比如字体的大小：   

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

然后调用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;
    }

此方法主要做两件事：第一，改变当前的configuration，将新的数据放进去。第二，保证正在运行的应用程序界面更新最新的configuration。先调用updateFrom()方法，遍历configuration包含的属性是否改变，如果有改变就返回一个对应的整数，如果没有改变就返回0。就语言改变而言，根据上面的分析，configuration至少有3个属性发生了改变：fontscale（之前没有设置字体的效果就不会改变）、locale和布局的direction。

有了新的数据就要保存，保存在configuration中不是个事。对于Android系统而言，改变语言，有两个地方的数据需要更新，一个是SystemProperties，另一个是数据库。前者以键值对的形式存放数据，多用于System，后者保存于DataBase中，多用于应用程序获取，算是对外开放的数据。上面方法中对这两个地方都进行了数据保存操作:

1)SystemProperties：调用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:调用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;

该保存的数据保存了，但是Resource还不知道这档子事，因为Android代码和资源是分开的，Resource不知道Configuration发生了变化，Resource就不会去加载正确的资源。所以接下来此方法调用了mSystemThread.applyConfigurationToResources(configCopy)来完成这件事，mSystemThread是一个ActivityThread对象，其初始化在ActivityManagerService的构造函数中完成：   

mSystemThread = ActivityThread.currentActivityThread();

//此方法属于ActivityThread
    public final void applyConfigurationToResources(Configuration config) {
        synchronized (mResourcesManager) {
            mResourcesManager.applyConfigurationToResourcesLocked(config, null);
        }
    }
    //此方法属于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都会去更新configuration，configuration所包含的属性都会遍历到，该更新的数据更新，该清除的缓存清除。

到这里，第一件事算是做完了，就要做第二件事，让新的configuration更新到所有界面，updateConfigurationLocked()方法通过遍历保存在ProcessRecord中的进程，然后通过scheduleConfigurationChanged()方法更新它们的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) {
     }
 }

此处通过Binder机制调用ApplicationThreadNative.java中的scheduleConfigurationChanged()方法，最后调用到ActivityThread中的内部类ApplicationThread的scheduleConfigurationChanged()方法，函数调用堆栈如图：

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);
            }
        }
    }

到这里设置语言以后，代码跑的流程就基本结束了，需要一提的是performConfigurationChanged()方法。为什么要提它呢？因为有时候写应用的时候activity需要关注一些configChanged，如：android:configChanges="orientation|keyboardHidden|screenSize"，然后重写onConfigurationChanged()方法。然而触发这个方法回调的触发点在哪里呢？这里就以设置语言为例，设置语言触发了configuration的改变。先来看下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确实改变了，那么此方法中就会调用cb.onConfigurationChanged(config)。cb代表ComponentCallbacks2，而ComponentCallbacks2 又继承于ComponentCallbacks，所以onConfigurationChanged()方法属于ComponentCallbacks，同样Activity类也实现了ComponentCallbacks2这个接口，如此一来这个回调的过程就连接上了。也充分说明了为什么在configuration改变以后，activity关注的config会回调其父类的onConfigurationChanged()方法。

最后就是广播configuration改变了，updateConfigurationLocked()广播了ACTION_CONFIGURATION_CHANGED和ACTION_LOCALE_CHANGED，使用的方法是broadcastIntentLocked()，此方法广播成功返回BROADCAST_SUCCESS。具体就不多说了。