Settings 启动流程

Settings 启动流程

1. Settings-->Manifest.xml-->action.MAIN-->SettingsHomepageActivity

   public class SettingsHomepageActivity extends FragmentActivity {
         @Override
       protected void onCreate(Bundle savedInstanceState) {
             super.onCreate(savedInstanceState);
               //Settings首页布局
           setContentView(R.layout.settings_homepage_container);
           //一级菜单主要内容，跳转至TopLevelSettings显示
           showFragment(new TopLevelSettings(), R.id.main_content);
       }
   }
   ​

   public class TopLevelSettings extends DashboardFragment {
           //根据Fragment生命周期运行
            @Override
       public void onAttach(Context context) {
           super.onAttach(context);
           //获取item controler并设置对应的Activity，locate in DashboardFragment.java
    use(SupportPreferenceController.class).setActivity(getActivity());
           ...
           //fragment剩余生命周期在执行父类DashboardFragment中的生命周期
       }
       
           @Override
       protected String getLogTag() {
           return TAG;//TAG = "TopLevelSettings"
       }
       //获取main_item 布局id
           @Override
       protected int getPreferenceScreenResId() {
           return R.xml.top_level_settings;
       }
           
    }

   public abstract class DashboardFragment extends SettingsPreferenceFragment {
       ...
        @Override
       public void onCreate(Bundle icicle) {
           super.onCreate(icicle);
           // Set ComparisonCallback so we get better animation when list changes.
           getPreferenceManager().setPreferenceComparisonCallback(
                   new PreferenceManager.SimplePreferenceComparisonCallback());
          
           if (icicle != null) {
               // Upon rotation configuration change we need to update preference states before any
               // editing dialog is recreated (that would happen before onResume is called).
               //首次不调用，初始化Controller。第二次调用，更新Preference
               updatePreferenceStates();
           }
       }
       //Log显示调用方法创建Preference列表
           @Override
       public void onCreatePreferences(Bundle savedInstanceState, String rootKey) {
           refreshAllPreferences(getLogTag());
       }
       
       //TopLevelSettings.java重写该方法
       protected abstract String getLogTag();
       
       private void refreshAllPreferences(final String TAG) {
           final PreferenceScreen screen = getPreferenceScreen();
           // First remove old preferences.
           if (screen != null) {
               // Intentionally do not cache PreferenceScreen because it will be recreated later.
               screen.removeAll();
           }
   ​
           // Add resource based tiles.
           displayResourceTiles();//静态方式加载Settings一级菜单main item 
   ​
           refreshDashboardTiles(TAG);//动态刷新main_content 状态
   ​
           final Activity activity = getActivity();
           if (activity != null) {
               Log.d(TAG, "All preferences added, reporting fully drawn");
               activity.reportFullyDrawn();
           }
   ​
           updatePreferenceVisibility(mPreferenceControllers);
       }
       
           private void displayResourceTiles() {
               final int resId = getPreferenceScreenResId();//TopLevelSettings.java重写该方法获取main_content对应布局id
            if (resId <= 0) {
               return;
            }
            addPreferencesFromResource(resId);
       }
               
           void refreshDashboardTiles(final String TAG) {
               final PreferenceScreen screen = getPreferenceScreen();
   ​
               final DashboardCategory category =
                   mDashboardFeatureProvider.getTilesForCategory(getCategoryKey());
               if (category == null) {
               Log.d(TAG, "NO dashboard tiles for " + TAG);
               return;
               }
           ....
           }
       
       
           protected <T extends AbstractPreferenceController> T use(Class<T> clazz) {
               List<AbstractPreferenceController> controllerList = mPreferenceControllers.get(clazz);
               if (controllerList != null) {
               if (controllerList.size() > 1) {
                   Log.w(TAG, "Multiple controllers of Class " + clazz.getSimpleName()
                           + " found, returning first one.");
               }
                return (T) controllerList.get(0);
            }
   ​
            return null;
       }
   }
     

   //top_level_settings.xml
   ​
   <PreferenceScreen
       xmlns:android="http://schemas.android.com/apk/res/android"
       xmlns:settings="http://schemas.android.com/apk/res-auto"
       android:key="top_level_settings">
           <Preference
           android:key="top_level_network"
           android:title="@string/network_dashboard_title"
           android:summary="@string/summary_placeholder"
           android:icon="@drawable/ic_homepage_network"
           android:order="-120"
           android:fragment="com.android.settings.network.NetworkDashboardFragment"
           settings:controller="com.android.settings.network.TopLevelNetworkEntryPreferenceController"/>
           ...
           <Preference
           android:key="top_level_security"    //每个item必须有key属性
           android:title="@string/security_settings_title" 
           android:summary="@string/summary_placeholder"
           android:icon="@drawable/ic_homepage_security"
           android:order="-40"     //负值：绝对值越大越靠前；正值，绝对值越大越靠后
           android:fragment="com.android.settings.security.SecuritySettings"   //点击item对应跳转的fragment
           settings:controller="com.android.settings.security.TopLevelSecurityEntryPreferenceController"/>     //当前item的controller；每个item都必须要有该属性，也可直接在相关fragment中实现createPreferenceControllers()方法去调用构造相关controller.
         
           ....
       
       
   </PreferenceScreen>    

2.