Android 7.0Settings加载主界面流程

新人一枚，没有整机环境，有什么写的不对欢迎批评指正，万分感谢！

Settings主界面加载时序图（这里很多判断逻辑我省略掉了。更多的是想把加载主界面流程跑通。）

这张流程图将主fragment DashboardSummary启动，RecyclerView数据加载刷新 显示得较为明白。但是对于主界面tile分类，tile排序，tile对象属性是无法得知的。所以接下我就主要讲讲这两个。

（1）先看一下主界面布局（用绘图画的，比较丑见谅）

这里有一个值得学习的是RecycleView分类加载不同的布局，值得学习。方法在DashboardAdapter.Java里面。

主界面对象介绍：

（1）主界面（除了Suggestion，condition）其他对象都在List<DashBoardCagtory> Categories里面

（2） Categories 有 4个对象。4个DashBoardCagtory的title值分别是 Wireless&networks，Device，Personal，System

（3）各个Cagtories都有List<Tile> tiles 是各个DashBoardCagtorytitle下面各个tile的集合

         组装这些对象是时序图中方法4，5，6，7，8。

5 getTilesForAction 

（1）组装Intent对象

（2）调用方法6

    private static void getTilesForAction(Context context,            UserHandle user, String action, Map<Pair<String, String>, Tile> addedCache,            String defaultCategory, ArrayList<Tile> outTiles, boolean requireSettings) {        Intent intent = new Intent(action);        if (requireSettings) {            intent.setPackage(SETTING_PKG);        }        getTilesForIntent(context, user, intent, addedCache, defaultCategory, outTiles,                requireSettings, true);    }

6 getTilesForIntent

（1）利用PM查询所有含有方法5生成的intent对象的ResolveInfo集合

（2）获取集合中每一个Acitvity manifest配置的meta标签name为SETTINGS_ACTION的value值

（3）把activity name 和package  生成Intent对象

（4）将2步骤的值赋值给Tile  category

（5）获取action为SETTINGS_ACTION的intent-filter的priority属性

（6）将解析meta-data标签的bundle数据赋值给Tile metaData

public static void getTilesForIntent(Context context, UserHandle user, Intent intent,            Map<Pair<String, String>, Tile> addedCache, String defaultCategory, List<Tile> outTiles,            boolean usePriority, boolean checkCategory) {        PackageManager pm = context.getPackageManager();        List<ResolveInfo> results = pm.queryIntentActivitiesAsUser(intent,                PackageManager.GET_META_DATA, user.getIdentifier());        for (ResolveInfo resolved : results) {            if (!resolved.system) {                continue;            }            ActivityInfo activityInfo = resolved.activityInfo;            Bundle metaData = activityInfo.metaData;            String categoryKey = defaultCategory;            if (checkCategory && ((metaData == null) || !metaData.containsKey(EXTRA_CATEGORY_KEY))                    && categoryKey == null) {                continue;            } else {                categoryKey = metaData.getString(EXTRA_CATEGORY_KEY);            }            Pair<String, String> key = new Pair<String, String>(activityInfo.packageName,                    activityInfo.name);            Tile tile = addedCache.get(key);            if (tile == null) {                tile = new Tile();                tile.intent = new Intent().setClassName(                        activityInfo.packageName, activityInfo.name);                tile.category = categoryKey;                tile.priority = usePriority ? resolved.priority : 0;                tile.metaData = activityInfo.metaData;                updateTileData(context, tile, activityInfo, activityInfo.applicationInfo,                        pm);                if (DEBUG) Log.d(LOG_TAG, "Adding tile " + tile.title);                addedCache.put(key, tile);            }            if (!tile.userHandle.contains(user)) {                tile.userHandle.add(user);            }            if (!outTiles.contains(tile)) {                outTiles.add(tile);            }        }    }

7 updateTileData

（1） 解析meta-data标签 获取name为 META_DATA_PREFERENCE_ICON的value值赋值给icon

（2）解析meta-data标签 获取name为 META_DATA_PREFERENCE_TITLE的resource值赋值给title

（3）解析meta-data标签 获取name为 META_DATA_PREFERENCE_SUMMARY的value值赋值给summary

（4）如果title为空就获取acitvity标签label属性赋值给title

（5）如果icon等于0就获取acitvity标签icon属性赋值给icon

  private static boolean updateTileData(Context context, Tile tile,            ActivityInfo activityInfo, ApplicationInfo applicationInfo, PackageManager pm) {        if (applicationInfo.isSystemApp()) {            int icon = 0;            CharSequence title = null;            String summary = null;            try {                Resources res = pm.getResourcesForApplication(                        applicationInfo.packageName);                Bundle metaData = activityInfo.metaData;                if (res != null && metaData != null) {                    if (metaData.containsKey(META_DATA_PREFERENCE_ICON)) {                        icon = metaData.getInt(META_DATA_PREFERENCE_ICON);                    }                    if (metaData.containsKey(META_DATA_PREFERENCE_TITLE)) {                        if (metaData.get(META_DATA_PREFERENCE_TITLE) instanceof Integer) {                            title = res.getString(metaData.getInt(META_DATA_PREFERENCE_TITLE));                        } else {                            title = metaData.getString(META_DATA_PREFERENCE_TITLE);                        }                    }                    if (metaData.containsKey(META_DATA_PREFERENCE_SUMMARY)) {                        if (metaData.get(META_DATA_PREFERENCE_SUMMARY) instanceof Integer) {                            summary = res.getString(metaData.getInt(META_DATA_PREFERENCE_SUMMARY));                        } else {                            summary = metaData.getString(META_DATA_PREFERENCE_SUMMARY);                        }                    }                }            } catch (PackageManager.NameNotFoundException | Resources.NotFoundException e) {                if (DEBUG) Log.d(LOG_TAG, "Couldn't find info", e);            }            if (TextUtils.isEmpty(title)) {                title = activityInfo.loadLabel(pm).toString();            }            if (icon == 0) {                icon = activityInfo.icon;            }            tile.icon = Icon.createWithResource(activityInfo.packageName, icon);            tile.title = title;            tile.summary = summary;            tile.intent = new Intent().setClassName(activityInfo.packageName,                    activityInfo.name);            return true;        }        return false;    }

8 createCategory

（1）创建DashboardCategory对象

（2）利用PM查询所有含有Tile对象categoriyKey生成的intent对象的ResolveInfo集合

（3）把acitivity label值赋值给category title属性

（4）把解析intent-filter标签的priority值赋值给category属性

    private static DashboardCategory createCategory(Context context, String categoryKey) {        DashboardCategory category = new DashboardCategory();        category.key = categoryKey;        PackageManager pm = context.getPackageManager();        List<ResolveInfo> results = pm.queryIntentActivities(new Intent(categoryKey), 0);        if (results.size() == 0) {            return null;        }        for (ResolveInfo resolved : results) {            if (!resolved.system) {                // Do not allow any app to add to settings, only system ones.                continue;            }            category.title = resolved.activityInfo.loadLabel(pm);            category.priority = SETTING_PKG.equals(                    resolved.activityInfo.applicationInfo.packageName) ? resolved.priority : 0;            if (DEBUG) Log.d(LOG_TAG, "Adding category " + category.title);        }        return category;    }

4 getCategories

（1）调用5

（2）新建categoryMap集合

（3）遍历tiles，判断集合中是否有元素含有tile.category(当时我看见这个觉得google多此一举每次这个对象都是需要new但是我后来整        理manifest发现    含有相同category的tile很多。可以看我下面整理的manifest的表格)。如果没有就执行方法8

（4）将拥有相同属性category的tile加入到对象DashboardCategory category对象的list<tile>集合中（我觉得google写这个自己也蒙    蔽了。两个相同名字，           一个是Tile里面变量，一个是DashboardCategory对象）

（5）将categoryMap的值赋值给List <DashboardCategory>cagtories以便执行排序算法

（6）遍历cagtories利用Collections函数和比较器TILE_COMPARATOR将category.tiles按照priority从大到小排序

（7）利用Collections函数和比较器CATEGORY_COMPARATOR将categories按照priority从大到小排序

public static List<DashboardCategory> getCategories(Context context,            HashMap<Pair<String, String>, Tile> cache) {        final long startTime = System.currentTimeMillis();        boolean setup = Global.getInt(context.getContentResolver(), Global.DEVICE_PROVISIONED, 0)                != 0;        ArrayList<Tile> tiles = new ArrayList<>();        UserManager userManager = UserManager.get(context);        for (UserHandle user : userManager.getUserProfiles()) {            // TODO: Needs much optimization, too many PM queries going on here.            if (user.getIdentifier() == ActivityManager.getCurrentUser()) {                // Only add Settings for this user.                getTilesForAction(context, user, SETTINGS_ACTION, cache, null, tiles, true);                getTilesForAction(context, user, OPERATOR_SETTINGS, cache,                        OPERATOR_DEFAULT_CATEGORY, tiles, false);                getTilesForAction(context, user, MANUFACTURER_SETTINGS, cache,                        MANUFACTURER_DEFAULT_CATEGORY, tiles, false);            }            if (setup) {                getTilesForAction(context, user, EXTRA_SETTINGS_ACTION, cache, null, tiles, false);            }        }        HashMap<String, DashboardCategory> categoryMap = new HashMap<>();        for (Tile tile : tiles) {            DashboardCategory category = categoryMap.get(tile.category);            if (category == null) {                category = createCategory(context, tile.category);                if (category == null) {                    Log.w(LOG_TAG, "Couldn't find category " + tile.category);                    continue;                }                categoryMap.put(category.key, category);            }            category.addTile(tile);        }        ArrayList<DashboardCategory> categories = new ArrayList<>(categoryMap.values());        for (DashboardCategory category : categories) {            Collections.sort(category.tiles, TILE_COMPARATOR);        }        Collections.sort(categories, CATEGORY_COMPARATOR);        if (DEBUG_TIMING) Log.d(LOG_TAG, "getCategories took "                + (System.currentTimeMillis() - startTime) + " ms");        return categories;    }

图表：tile

图表：DashboardCategory

问题：summary是无法从manifest文件里面获取的。因为不含有meta-data name属性为“com.android.settings.summary”的标签。summary获取方法是时序图中方法16，17，18，31，32

16 new SummaryLoader

（1） 创建Handler对象

（2） 创建异步线程（大家可以去看一下线程优先级，做app还是挺有用处的）

（3） 遍历categories里面每一个DashboardCategory对象里面集合Tiles里面每一个tile对象

（4） 发送消息执行方法17

    public SummaryLoader(Activity activity, List<DashboardCategory> categories) {        mHandler = new Handler();        mWorkerThread = new HandlerThread("SummaryLoader", Process.THREAD_PRIORITY_BACKGROUND);        mWorkerThread.start();        mWorker = new Worker(mWorkerThread.getLooper());        mActivity = activity;        for (int i = 0; i < categories.size(); i++) {            List<Tile> tiles = categories.get(i).tiles;            for (int j = 0; j < tiles.size(); j++) {                Tile tile = tiles.get(j);                mWorker.obtainMessage(Worker.MSG_GET_PROVIDER, tile).sendToTarget();            }        }    }

17 makeProviderW

（1）执行方法18

（2）将方法18返回的SummaryProvider对象存入到mSummaryMap中

    private synchronized void makeProviderW(Tile tile) {        SummaryProvider provider = getSummaryProvider(tile);        if (provider != null) {            if (DEBUG) Log.d(TAG, "Creating " + tile);            mSummaryMap.put(provider, tile.intent.getComponent());        }    }

18 getSummaryProvider（真的是厉害了，我的歌）

（1）获取title中的meataData变量

（2）将bundle数据metaData键为SettingsActivity.META_DATA_KEY_FRAGMENT的alue值赋值给clsName

（3）根据clsName反射创建class

（4）获取name为SUMMARY_PROVIDER_FACORY的变量Field

（5）拿到Field的值强制转换为SummaryProviderFactory对象

（6）返回反射类中SummaryProvider对象

private SummaryProvider getSummaryProvider(Tile tile) {        if (!mActivity.getPackageName().equals(tile.intent.getComponent().getPackageName())) {            // Not within Settings, can't load Summary directly.            // TODO: Load summary indirectly.            return null;        }        Bundle metaData = getMetaData(tile);        if (metaData == null) {            if (DEBUG) Log.d(TAG, "No metadata specified for " + tile.intent.getComponent());            return null;        }        String clsName = metaData.getString(SettingsActivity.META_DATA_KEY_FRAGMENT_CLASS);        if (clsName == null) {            if (DEBUG) Log.d(TAG, "No fragment specified for " + tile.intent.getComponent());            return null;        }        try {            Class<?> cls = Class.forName(clsName);            Field field = cls.getField(SUMMARY_PROVIDER_FACTORY);            SummaryProviderFactory factory = (SummaryProviderFactory) field.get(null);            return factory.createSummaryProvider(mActivity, this);        } catch (ClassNotFoundException e) {            if (DEBUG) Log.d(TAG, "Couldn't find " + clsName, e);        } catch (NoSuchFieldException e) {            if (DEBUG) Log.d(TAG, "Couldn't find " + SUMMARY_PROVIDER_FACTORY, e);        } catch (ClassCastException e) {            if (DEBUG) Log.d(TAG, "Couldn't cast " + SUMMARY_PROVIDER_FACTORY, e);        } catch (IllegalAccessException e) {            if (DEBUG) Log.d(TAG, "Couldn't get " + SUMMARY_PROVIDER_FACTORY, e);        }        return null;    }

以NotificationApps.java为例

public class NotificationApps extends ManageApplications {    private static class SummaryProvider implements SummaryLoader.SummaryProvider {        private final Context mContext;        private final SummaryLoader mLoader;        private final NotificationBackend mNotificationBackend;        private SummaryProvider(Context context, SummaryLoader loader) {            mContext = context;            mLoader = loader;            mNotificationBackend = new NotificationBackend();        }        @Override        public void setListening(boolean listening) {            if (listening) {                new AppCounter(mContext) {                    @Override                    protected void onCountComplete(int num) {                        updateSummary(num);                    }                    @Override                    protected boolean includeInCount(ApplicationInfo info) {                        return mNotificationBackend.getNotificationsBanned(info.packageName,                                info.uid);                    }                }.execute();            }        }        private void updateSummary(int count) {            if (count == 0) {                mLoader.setSummary(this, mContext.getString(R.string.notification_summary_none));            } else {                mLoader.setSummary(this, mContext.getResources().getQuantityString(                        R.plurals.notification_summary, count, count));            }        }    }    public static final SummaryLoader.SummaryProviderFactory SUMMARY_PROVIDER_FACTORY            = new SummaryLoader.SummaryProviderFactory() {        @Override        public SummaryLoader.SummaryProvider createSummaryProvider(Activity activity,                                                                   SummaryLoader summaryLoader) {            return new SummaryProvider(activity, summaryLoader);        }    };}

31 setListening

（1） 移除消息Worker.MSG_SET_LISTENING

（2） 发送消息Worker.MSG_SET_LISTENING执行方法32

public void setListening(boolean listening) {        if (mListening == listening) return;        mListening = listening;        // Unregister listeners immediately.        for (int i = 0; i < mReceivers.size(); i++) {            mActivity.unregisterReceiver(mReceivers.valueAt(i));        }        mReceivers.clear();        mWorker.removeMessages(Worker.MSG_SET_LISTENING);        mWorker.obtainMessage(Worker.MSG_SET_LISTENING, listening ? 1 : 0, 0).sendToTarget();    }

32 setListeningW(注意锁)

（1）遍历方法18生成的mSummaryMap键SummaryProvider

（2）将反射fragment类中静态内部类执行setListening方法

    private synchronized void setListeningW(boolean listening) {        if (mWorkerListening == listening) return;        mWorkerListening = listening;        if (DEBUG) Log.d(TAG, "Listening " + listening);        for (SummaryProvider p : mSummaryMap.keySet()) {            try {                p.setListening(listening);            } catch (Exception e) {                Log.d(TAG, "Problem in setListening", e);            }        }    }

到此界面第一次刷新完成。Suggestion这个类我还没研究透彻。所以就没有画到时序图里面。主要类是SuggestionParser.java

再介绍一下Settings.java的作用

正常我们写很多activity。是不是该这样写：

for(int i = 1 ; i <=需要新建activity的个数;i++) {   新建class Activityi extends SettingsActivity}

这样做没有什么不对，也不会对性能有影响。但是SettingsActivity真的是爸爸，儿子们需要做的都被爸爸干完了，所以你会发现许多空白文件。

Google就利用java静态内部类的机制（可以去百度一下）编译就会生成他的宿主类名$静态内部类名 也就是我们manifest看见类似于Settings$WirelessSettings。这样写就避免大量白痴文件。

Google 这次7.0Settings加载逻辑大改其实对于新界面开发更容易了。只要去manifest将你的activity属性配置好。Settings.java声明。目前代码逻辑就能直接把你界面加载完毕。然后你去对应的fragment实现逻辑。这样新界面开发基本不需要改动现有逻辑。真的是厉害了，我的歌！