从源码中看到Settings继承SettingsActivity，而SettingsActivity继承SettingsDrawerActivity，在SettingsDrawerActivity的onCreate方法中，我们看到调用了getDashboardCategories方法，代码：
跟进到该方法的具体实现：
public List<DashboardCategory> getDashboardCategories() {
if (sDashboardCategories == null) {
sTileCache = new HashMap<>();
sConfigTracker = new InterestingConfigChanges();
// Apply initial current config.
boolean newC =sConfigTracker.applyNewConfig(getResources());
Log.d(TAG, "newC = " + newC);
sDashboardCategories = TileUtils.getCategories(this, sTileCache);//重点在这里
}
return sDashboardCategories;
}
跟进到getCategories方法：
private static final String EXTRA_SETTINGS_ACTION =
"com.android.settings.action.EXTRA_SETTINGS";
/**
* Same as #EXTRA_SETTINGS_ACTION but used for the platform Settings activities.
*/
private static final String SETTINGS_ACTION =
"com.android.settings.action.SETTINGS";
private static final String OPERATOR_SETTINGS =
"com.android.settings.OPERATOR_APPLICATION_SETTING";
private static final String OPERATOR_DEFAULT_CATEGORY =
"com.android.settings.category.wireless";
private static final String MANUFACTURER_SETTINGS =
"com.android.settings.MANUFACTURER_APPLICATION_SETTING";
private static final String MANUFACTURER_DEFAULT_CATEGORY =
"com.android.settings.category.device";
//以上是TileUtils.java定义的常量
public static List<DashboardCategory> getCategories(Context context,
HashMap<Pair<String, String>, Tile> cache) {
//......省略
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);
&n