Android Settings 跳转流程方法详解

 @Override
    public boolean onPreferenceTreeClick(Preference preference) {
        final Collection<List<AbstractPreferenceController>> controllers =
                mPreferenceControllers.values();
        for (List<AbstractPreferenceController> controllerList : controllers) {
            for (AbstractPreferenceController controller : controllerList) {
                if (controller.handlePreferenceTreeClick(preference)) {
                    // log here since calling super.onPreferenceTreeClick will be skipped
                    writePreferenceClickMetric(preference);
                    return true;
                }
            }
        }
        return super.onPreferenceTreeClick(preference);
    }

    @Override
    public boolean onPreferenceTreeClick(Preference preference) {
        writePreferenceClickMetric(preference);
        return super.onPreferenceTreeClick(preference);
    }

    @Override
    public boolean onPreferenceStartFragment(PreferenceFragmentCompat caller, Preference pref) {
        new SubSettingLauncher(this)
                .setDestination(pref.getFragment())
                .setArguments(pref.getExtras())
                .setSourceMetricsCategory(caller instanceof Instrumentable
                        ? ((Instrumentable) caller).getMetricsCategory()
                        : Instrumentable.METRICS_CATEGORY_UNKNOWN)
                .setTitleRes(-1)
                .launch();
        return true;
    }

@Override  
    protected void onCreate(Bundle savedState) {  
        super.onCreate(savedState);  
        long startTime = System.currentTimeMillis();  
        //工厂类实现方法com.android.settings.overlay.FeatureFactoryImpl.java  
        final FeatureFactory factory = FeatureFactory.getFactory(this);  
        //获取菜单信息的工厂类，实现类为DashboardFeatureProviderImpl.java  
        mDashboardFeatureProvider = factory.getDashboardFeatureProvider(this);  
        mMetricsFeatureProvider = factory.getMetricsFeatureProvider();  
 // 第一步    从intent信息中获取<meta-data/>标签名为"com.android.settings.FRAGMENT_CLASS"的值（下文用于加载Fragment的类名）  
        getMetaData();  
 // 第二步
      final Intent intent = getIntent();
      if (intent.hasExtra(EXTRA_UI_OPTIONS)) {
          getWindow().setUiOptions(intent.getIntExtra(EXTRA_UI_OPTIONS, 0));
      }
        //获取上面getMetaData()得到的类名  
        final String initialFragmentName = intent.getStringExtra(EXTRA_SHOW_FRAGMENT);  
        //是否为快捷进入方式（如从其它的应用进入Settings的某个设置项）  
        mIsShortcut = isShortCutIntent(intent) || isLikeShortCutIntent(intent) ||  
                intent.getBooleanExtra(EXTRA_SHOW_FRAGMENT_AS_SHORTCUT, false);  
        ... ...  
        if (savedState != null) {  
          ... ...  
        } else {  
 //  第三步   加载布局  
            launchSettingFragment(initialFragmentName, isSubSettings, intent);  
        }  
        ... ...  
    }