Settings学习总结(一)

个人对settings一些学习总结，在介绍Settings一级菜单栏之前先讲解一下如何添加一级菜单栏，这样可以更好的理解后面的一级菜单栏显示流程

添加一级菜单栏

在Settings.java中添加代码

public static class TestSettingsActivity extends SetttingsActvity{}

添加了activity之后肯定是需要在清单文件中进行配置

<activityandroid:name="Settings$TestSettingsActivity"android:label="标签"android:icon="图标"android:taskAffinity="com.android.settings"android:parentActivityName="Settings"><!-- android:priority 跟一级菜单栏排序相关，在后面的显示流程会讲解 --><intent-filter android:priority="9"><action android:name="com.android.settings.action.SETTINGS" /></intent-filter><!-- 显示在那个分类，这个定义设置是根据源码配置相关的，后面显示流程会说明 --><meta-data android:name="com.android.settings.category"android:value="com.android.settings.category.device" /><!-- 点击后调整的fragment页，如果不设置会显示设置主页面，后面会说明为什么--><meta-data android:name="com.android.settings.FRAGMENT_CLASS"android:value="com.android.settings.DisplaySettings" /><!--  --><meta-data android:name="com.android.settings.PRIMARY_PROFILE_CONTROLLED"android:value="true" /><!-- 标题，如果不设置标题则会采用label标签的内容 --><meta-data android:name="com.android.settings.title"android:resource="标题"/><!-- 提示 --><meta-data android:name="com.android.settings.summary"android:resource="提示内容"/></activity>

配置好后就可以在一级菜单栏看见你设置的一级菜单了

Settings一级菜单栏显示流程

其实通过添加时我们可以发现Activity继承的是SettingsActivity，包括Settings.java也是继承的SettingsActivity，可以判断SettingsActivity是非常重要的一个activity
Settings在打开运行的时候会先执行SettingsActivity中onCreate方法，在onCreate中有一个getMetaData方法，看源码

private void getMetaData() {try {ActivityInfo ai = getPackageManager().getActivityInfo(getComponentName(),PackageManager.GET_META_DATA);if (ai == null || ai.metaData == null) return;mFragmentClass = ai.metaData.getString(META_DATA_KEY_FRAGMENT_CLASS);} catch (NameNotFoundException nnfe) {// No recoveryLog.d(LOG_TAG, "Cannot get Metadata for: " + getComponentName().toString());}}

获取你在清单文件里配置的activity中的name为FRAGMENT_CLASS的meta-data参数配置fragment，比如上面我们添加的一级菜单栏，我们设置的点击后跳转的页面是DisplaySettings，那就是获取的就是这个页面
然后会执行Settings重写的getIntent方法，看源码

@Overridepublic Intent getIntent() {Intent superIntent = super.getIntent();String startingFragment = getStartingFragmentClass(superIntent);...}

private String getStartingFragmentClass(Intent intent) {if (mFragmentClass != null) return mFragmentClass;String intentClass = intent.getComponent().getClassName();...return intentClass;}

再结合整体源码，我们可以看出来，如果获取到跳转的页面就显示，获取不到就显示设置主页面，接着往下走

mIsShowingDashboard = className.equals(Settings.class.getName());
...
setContentView(mIsShowingDashboard ?R.layout.settings_main_dashboard : R.layout.settings_main_prefs);

获取是否是设置主页面，通过获取的mIsShowingDashboard 参数来判断显示一级菜单栏页面还是二级菜单栏页面
然后会执行 launchSettingFragment 方法

@VisibleForTestingvoid launchSettingFragment(String initialFragmentName, boolean isSubSettings, Intent intent) {if (!mIsShowingDashboard && initialFragmentName != null) {setTitleFromIntent(intent);Bundle initialArguments = intent.getBundleExtra(EXTRA_SHOW_FRAGMENT_ARGUMENTS);switchToFragment(initialFragmentName, initialArguments, true, false,mInitialTitleResId, mInitialTitle, false);} else {// Show search icon as up affordance if we are displaying the main DashboardmInitialTitleResId = R.string.dashboard_title;switchToFragment(DashboardSummary.class.getName(), null /* args */, false, false,mInitialTitleResId, mInitialTitle, false);}}

最后会执行switchToFragment 方法

/*** Switch to a specific Fragment with taking care of validation, Title and BackStack*/private Fragment switchToFragment(String fragmentName, Bundle args, boolean validate,boolean addToBackStack, int titleResId, CharSequence title, boolean withTransition) {Log.d(LOG_TAG, "Switching to fragment " + fragmentName);...Fragment f = Fragment.instantiate(this, fragmentName, args);...return f;}

根据这两段代码，我们可以看出设置主页面最后展示的是DashboardSummary，然后我们看DashboardSummary中onCreate方法

@Overridepublic void onCreate(Bundle savedInstanceState) {long startTime = System.currentTimeMillis();super.onCreate(savedInstanceState);final Activity activity = getActivity();String[] categoriesName = activity.getResources().getStringArray(R.array.freeme_dashboard_categories);...}

categoriesName就是分类列表，根据源码流程，最后会通过updateCategory方法获取列表数据,根据源码继续往下走会走到CategoryManager中的tryInitCategories方法，在这个方法中调用了TileUtils中的getCategories方法，其实走到这里我们会发现，获取一级菜单栏列表及排序并不是在Settings里进行控制，而是在SettingsLib里进行控制
说会TileUtils，这个类说白了就是通过action及packagename来获取在可以显示的action及action的信息，我们看里面的一些方法
getTilesForAction，这个方法就是通过action及packagename来获取可显示的一级菜单栏，看源码，最终会走到这个方法里面

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

方法里执行的getTilesForIntent就是通过action及packagename获取的菜单栏进行整理并放入一整个列表中，之后会执行这段代码

HashMap<String, DashboardCategory> categoryMap = new HashMap<>();for (Tile tile : tiles) {DashboardCategory category = categoryMap.get(tile.category);if (category == null) {category = createCategory(context, tile.category, categoryDefinedInManifest);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) {category.sortTiles();}Collections.sort(categories, CATEGORY_COMPARATOR);

将所有的一级菜单栏进行分类和排序，排序一般是根据priority惨数来判断，思考一下，如果两个设置的priority参数一致，怎么排序，看源码

//CategoryManager
private synchronized void tryInitCategories(Context context, boolean forceClearCache,String settingPkg) {if (mCategories == null) {if (forceClearCache) {mTileByComponentCache.clear();}mCategoryByKeyMap.clear();//通过TileUtils中的getCategories方法获取设置列表mCategories = TileUtils.getCategories(context, mTileByComponentCache,false /* categoryDefinedInManifest */, mExtraAction, settingPkg);for (DashboardCategory category : mCategories) {mCategoryByKeyMap.put(category.key, category);}/*/ freeme.wanglei, 20180622. FreemeAppTheme, no need backword compat for freeme stylebackwardCompatCleanupForCategory(mTileByComponentCache, mCategoryByKeyMap);//*///排序方法sortCategories(context, mCategoryByKeyMap);filterDuplicateTiles(mCategoryByKeyMap);}}@VisibleForTestingsynchronized void sortCategories(Context context,Map<String, DashboardCategory> categoryByKeyMap) {for (Entry<String, DashboardCategory> categoryEntry : categoryByKeyMap.entrySet()) {categoryEntry.getValue().sortTiles(context.getPackageName());}}//DashboardCategory
public synchronized void sortTiles(String skipPackageName) {// Sort mTiles based on [priority, package within priority]Collections.sort(mTiles, (tile1, tile2) -> {final String package1 = tile1.intent.getComponent().getPackageName();final String package2 = tile2.intent.getComponent().getPackageName();final int packageCompare = CASE_INSENSITIVE_ORDER.compare(package1, package2);// First sort by priority//先通过两个设置的priority 参数来排序，如果priority 值一致final int priorityCompare = tile2.priority - tile1.priority;if (priorityCompare != 0) {return priorityCompare;}// Then sort by package name, skip package take precedence//根据设置名称的首字母的ASCII码来判断if (packageCompare != 0) {if (TextUtils.equals(package1, skipPackageName)) {return -1;}if (TextUtils.equals(package2, skipPackageName)) {return 1;}}return packageCompare;});}