Settings 体系架构五 NetworkDashboardFragment

NetworkDashboardFragment在Settings应用中，对应的是网络管理页面，它是继承自DashboardFragment，以该类来具体看一个DashboardFragment是怎么管理UI页面中。

NetworkDashboardFragment.java

public class NetworkDashboardFragment extends DashboardFragment implements
        MobilePlanPreferenceController.MobilePlanPreferenceHost {
    private static final String TAG = "NetworkDashboardFrag";
    // 重置网络
    private NetworkResetActionMenuController mNetworkResetController;

    @Override
    protected int getPreferenceScreenResId() { // 返回页面布局Id。
        return R.xml.network_and_internet;
    }

    @Override
    public void onAttach(Context context) {
        super.onAttach(context);
        mNetworkResetController = new NetworkResetActionMenuController(context);
    }

    @Override
    public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
        super.onCreateOptionsMenu(menu, inflater);
        mNetworkResetController.buildMenuItem(menu); // 添加重置网络菜单项
    }

    @Override // 返回Preference对应的Controller。
    protected List<PreferenceController> getPreferenceControllers(Context context) {
        final AirplaneModePreferenceController airplaneModePreferenceController =
                new AirplaneModePreferenceController(context, this /* fragment */);
        final MobilePlanPreferenceController mobilePlanPreferenceController =
                new MobilePlanPreferenceController(context, this);
        final WifiMasterSwitchPreferenceController wifiPreferenceController =
                new WifiMasterSwitchPreferenceController(context, mMetricsFeatureProvider);
        final MobileNetworkPreferenceController mobileNetworkPreferenceController =
                new MobileNetworkPreferenceController(context);
        final VpnPreferenceController vpnPreferenceController =
                new VpnPreferenceController(context);
        final Lifecycle lifecycle = getLifecycle();
        lifecycle.addObserver(airplaneModePreferenceController); // 飞行模式
        lifecycle.addObserver(mobilePlanPreferenceController); // 数据管理
        lifecycle.addObserver(wifiPreferenceController); // Wifi
        lifecycle.addObserver(mobileNetworkPreferenceController); // 移动数据
        lifecycle.addObserver(vpnPreferenceController); // vpn

        final List<PreferenceController> controllers = new ArrayList<>();
        controllers.add(airplaneModePreferenceController);
        controllers.add(mobileNetworkPreferenceController);
        controllers.add(new TetherPreferenceController(context, lifecycle));
        controllers.add(vpnPreferenceController);
        controllers.add(new ProxyPreferenceController(context));
        controllers.add(mobilePlanPreferenceController);
        controllers.add(wifiPreferenceController);
        return controllers;
    }

    @Override
    public void showMobilePlanMessageDialog() {
        showDialog(MANAGE_MOBILE_PLAN_DIALOG_ID);
    }

    @Override
    public Dialog onCreateDialog(int dialogId) {
        Log.d(TAG, "onCreateDialog: dialogId=" + dialogId);
        switch (dialogId) {
            case MANAGE_MOBILE_PLAN_DIALOG_ID:
                final MobilePlanPreferenceController controller =
                        getPreferenceController(MobilePlanPreferenceController.class);
                return new AlertDialog.Builder(getActivity())
                        .setMessage(controller.getMobilePlanDialogMessage())
                        .setCancelable(false)
                        .setPositiveButton(com.android.internal.R.string.ok,
                                (dialog, id) -> controller.setMobilePlanDialogMessage(null))
                        .create();
        }
        return super.onCreateDialog(dialogId);
    }

    @Override
    public int getDialogMetricsCategory(int dialogId) {
        if (MANAGE_MOBILE_PLAN_DIALOG_ID == dialogId) {
            return MetricsProto.MetricsEvent.DIALOG_MANAGE_MOBILE_PLAN;
        }
        return 0;
    }
}

network_and_internet.xml

<PreferenceScreen
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:settings="http://schemas.android.com/apk/res/com.android.settings"
    android:title="@string/network_dashboard_title">
    <!--WifiSettings-->
    <com.android.settings.widget.MasterSwitchPreference
        android:fragment="com.android.settings.wifi.WifiSettings"
        android:key="toggle_wifi"
        android:title="@string/wifi_settings"
        android:summary="@string/summary_placeholder"
        android:icon="@drawable/ic_settings_wireless"
        android:order="-30">
        <!--配置intent，点击该Preference，跳转到指定Activity。-->
        <intent
            android:action="android.settings.WIFI_SETTINGS"
            android:targetClass="Settings$WifiSettingsActivity"/>
    </com.android.settings.widget.MasterSwitchPreference>
    <!--MobileNetwork-->
    <com.android.settingslib.RestrictedPreference
        android:key="mobile_network_settings"
        android:title="@string/network_settings_title"
        android:icon="@drawable/ic_network_cell"
        android:dependency="toggle_airplane"
        android:order="-15"
        settings:keywords="@string/keywords_more_mobile_networks"
        settings:userRestriction="no_config_mobile_networks"
        settings:useAdminDisabledSummary="true">
        <intent
            android:action="android.intent.action.MAIN"
            android:targetPackage="com.android.phone"
            android:targetClass="com.android.phone.MobileNetworkSettings"/>
    </com.android.settingslib.RestrictedPreference>
    <!--Tether-->
    <com.android.settingslib.RestrictedPreference
        android:fragment="com.android.settings.TetherSettings"
        android:key="tether_settings"
        android:title="@string/tether_settings_title_all"
        android:icon="@drawable/ic_wifi_tethering"
        android:order="-5"
        android:summary="@string/summary_placeholder"
        settings:userRestriction="no_config_tethering"
        settings:useAdminDisabledSummary="true"/>
    <!--VPN-->
    <com.android.settingslib.RestrictedPreference
        android:fragment="com.android.settings.vpn2.VpnSettings"
        android:key="vpn_settings"
        android:title="@string/vpn_settings_title"
        android:icon="@drawable/ic_vpn_key"
        android:order="0"
        android:summary="@string/summary_placeholder"
        settings:userRestriction="no_config_vpn"
        settings:useAdminDisabledSummary="true"/>
    <!--MobilePlan-->
    <com.android.settingslib.RestrictedPreference
        android:key="manage_mobile_plan"
        android:title="@string/manage_mobile_plan_title"
        android:persistent="false"
        settings:userRestriction="no_config_mobile_networks"
        settings:useAdminDisabledSummary="true"/>
    <!--Airplane-->
    <SwitchPreference
        android:key="toggle_airplane"
        android:title="@string/airplane_mode"
        android:icon="@drawable/ic_airplanemode_active"
        android:disableDependentsState="true"
        android:order="5"/>
    <!--Proxy-->
    <Preference
        android:fragment="com.android.settings.ProxySelector"
        android:key="proxy_settings"
        android:title="@string/proxy_settings_title"/>
</PreferenceScreen>

xml中定义了PreferenceScreen和包含的子Preference

WifiMasterSwitchPreferenceController.java

拿WifiSettings作为例子分析，在getPreferenceControllers中，创建了该类的实例对象并返回。

public class WifiMasterSwitchPreferenceController extends PreferenceController
        implements SummaryUpdater.OnSummaryChangeListener,
        LifecycleObserver, OnResume, OnPause, OnStart, OnStop {
    // key，同上面network_and_internet.xml中定义的key
    public static final String KEY_TOGGLE_WIFI = "toggle_wifi";

    private MasterSwitchPreference mWifiPreference;
    private WifiEnabler mWifiEnabler;
    private final WifiSummaryUpdater mSummaryHelper;
    private final MetricsFeatureProvider mMetricsFeatureProvider;

    public WifiMasterSwitchPreferenceController(Context context,
            MetricsFeatureProvider metricsFeatureProvider) {
        super(context);
        mMetricsFeatureProvider = metricsFeatureProvider;
        mSummaryHelper = new WifiSummaryUpdater(mContext, this);
    }

    @Override // PreferenceScreen被创建之后立即被调用
    public void displayPreference(PreferenceScreen screen) {
        super.displayPreference(screen);
        mWifiPreference = (MasterSwitchPreference) screen.findPreference(KEY_TOGGLE_WIFI);
    }

    @Override
    public void onResume() {
        mSummaryHelper.register(true);
        if (mWifiEnabler != null) {
            mWifiEnabler.resume(mContext); 
            // WifiEnabler#resume启动广播监听
        }
    }

    @Override
    public void onPause() {
        if (mWifiEnabler != null) {
            mWifiEnabler.pause(); // 注销广播监听
        }
        mSummaryHelper.register(false);
    }

    @Override
    public void onStart() {
        mWifiEnabler = new WifiEnabler(mContext, new MasterSwitchController(mWifiPreference),
            mMetricsFeatureProvider);
        // 创建WifiEnabler，onResume的时候去监听广播，onPause时注销广播监听。
    }

    @Override
    public void onStop() {
        if (mWifiEnabler != null) {
            mWifiEnabler.teardownSwitchController();
        }
    }

    @Override
    public void onSummaryChanged(String summary) {
        if (mWifiPreference != null) {
            mWifiPreference.setSummary(summary);
            // 监听，比如wifi连接上了，会在当前页面显示连接的wifi名称
        }
    }
}

WifiEnabler.java

public class WifiEnabler implements SwitchWidgetController.OnSwitchChangeListener  {

    private final SwitchWidgetController mSwitchWidget;
    private final WifiManager mWifiManager;
    private final ConnectivityManagerWrapper mConnectivityManager;
    private final MetricsFeatureProvider mMetricsFeatureProvider;

    private Context mContext;
    private boolean mListeningToOnSwitchChange = false;
    private AtomicBoolean mConnected = new AtomicBoolean(false);

    private boolean mStateMachineEvent;
    private final IntentFilter mIntentFilter;
    private final BroadcastReceiver mReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            String action = intent.getAction();
            // WIFI状态发生改变时处理state
            if (WifiManager.WIFI_STATE_CHANGED_ACTION.equals(action)) {
                handleWifiStateChanged(mWifiManager.getWifiState());
            } else if (WifiManager.SUPPLICANT_STATE_CHANGED_ACTION.equals(action)) {
                if (!mConnected.get()) {
                    handleStateChanged(WifiInfo.getDetailedStateOf((SupplicantState)
                            intent.getParcelableExtra(WifiManager.EXTRA_NEW_STATE)));
                }
            } // Network状态改变
            else if (WifiManager.NETWORK_STATE_CHANGED_ACTION.equals(action)) {
                NetworkInfo info = (NetworkInfo) intent.getParcelableExtra(
                        WifiManager.EXTRA_NETWORK_INFO);
                mConnected.set(info.isConnected());
                handleStateChanged(info.getDetailedState());
            }
        }
    };

    private static final String EVENT_DATA_IS_WIFI_ON = "is_wifi_on";
    private static final int EVENT_UPDATE_INDEX = 0;

    public WifiEnabler(Context context, SwitchWidgetController switchWidget,
        MetricsFeatureProvider metricsFeatureProvider) {
        this(context, switchWidget, metricsFeatureProvider, new ConnectivityManagerWrapper(
            (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE)));
    }

    @VisibleForTesting
    WifiEnabler(Context context, SwitchWidgetController switchWidget,
            MetricsFeatureProvider metricsFeatureProvider,
            ConnectivityManagerWrapper connectivityManagerWrapper) {
        mContext = context;
        mSwitchWidget = switchWidget;
        // 设置switchWidget监听器OnSwitchChangeListener
        // 开关状态发生改变时，调用WifiManager打开/关闭wifi。
        mSwitchWidget.setListener(this);
        mMetricsFeatureProvider = metricsFeatureProvider;
        mWifiManager = (WifiManager) context.getSystemService(Context.WIFI_SERVICE);
        mConnectivityManager = connectivityManagerWrapper;

        mIntentFilter = new IntentFilter(WifiManager.WIFI_STATE_CHANGED_ACTION);
        // The order matters! We really should not depend on this. :(
        mIntentFilter.addAction(WifiManager.SUPPLICANT_STATE_CHANGED_ACTION);
        mIntentFilter.addAction(WifiManager.NETWORK_STATE_CHANGED_ACTION);

        setupSwitchController();
    }

    public void setupSwitchController() {
        final int state = mWifiManager.getWifiState();
        handleWifiStateChanged(state); // 更新state
        // ...
        mSwitchWidget.setupView();
    }

    public void teardownSwitchController() {
        if (mListeningToOnSwitchChange) {
            mSwitchWidget.stopListening();
            mListeningToOnSwitchChange = false;
        }
        mSwitchWidget.teardownView();
    }

    public void resume(Context context) {
        mContext = context;
        // Wi-Fi state is sticky, so just let the receiver update UI
        mContext.registerReceiver(mReceiver, mIntentFilter);
        // ...
    }

    public void pause() {
        mContext.unregisterReceiver(mReceiver);
        // ...
    }

    // 更新wifi状态改变。
    private void handleWifiStateChanged(int state) {
        // Clear any previous state
        mSwitchWidget.setDisabledByAdmin(null);
        switch (state) {
            case WifiManager.WIFI_STATE_ENABLING:
                break;
            case WifiManager.WIFI_STATE_ENABLED:
                setSwitchBarChecked(true);
                mSwitchWidget.setEnabled(true);
                break;
            case WifiManager.WIFI_STATE_DISABLING:
                break;
            case WifiManager.WIFI_STATE_DISABLED:
                setSwitchBarChecked(false);
                mSwitchWidget.setEnabled(true);
                break;
            default:
                setSwitchBarChecked(false);
                mSwitchWidget.setEnabled(true);
        }
        if (mayDisableTethering(!mSwitchWidget.isChecked())) {
            // ...
        }
    }

    private void setSwitchBarChecked(boolean checked) {
        mStateMachineEvent = true;
        mSwitchWidget.setChecked(checked);
        mStateMachineEvent = false;
    }

    private void handleStateChanged(@SuppressWarnings("unused") NetworkInfo.DetailedState state) {
        // After the refactoring from a CheckBoxPreference to a Switch, this method is useless since
        // there is nowhere to display a summary.
        // This code is kept in case a future change re-introduces an associated text.
        /*
        // WifiInfo is valid if and only if Wi-Fi is enabled.
        // Here we use the state of the switch as an optimization.
        if (state != null && mSwitch.isChecked()) {
            WifiInfo info = mWifiManager.getConnectionInfo();
            if (info != null) {
                //setSummary(Summary.get(mContext, info.getSSID(), state));
            }
        }
        */
    }

    @Override
    public boolean onSwitchToggled(boolean isChecked) {
        //Do nothing if called as a result of a state machine event
        if (mStateMachineEvent) {
            return true;
        }
        // Show toast message if Wi-Fi is not allowed in airplane mode
        if (isChecked && !WirelessUtils.isRadioAllowed(mContext, Settings.Global.RADIO_WIFI)) {
            Toast.makeText(mContext, R.string.wifi_in_airplane_mode, Toast.LENGTH_SHORT).show();
            // Reset switch to off. No infinite check/listenenr loop.
            mSwitchWidget.setChecked(false);
            return false;
        }

        // Disable tethering if enabling Wifi
        if (mayDisableTethering(isChecked)) {
            mConnectivityManager.stopTethering(ConnectivityManager.TETHERING_WIFI);
        }
        if (isChecked) {
            mMetricsFeatureProvider.action(mContext, MetricsEvent.ACTION_WIFI_ON);
        } else {
            // Log if user was connected at the time of switching off.
            mMetricsFeatureProvider.action(mContext, MetricsEvent.ACTION_WIFI_OFF,
                    mConnected.get());
        }
        // 调用WifiManager打开/关闭wifi，操作完成后会发送广播通知。
        // 在handleWifiStateChanged中，去处理广播事件。
        if (!mWifiManager.setWifiEnabled(isChecked)) {
            // Error
            mSwitchWidget.setEnabled(true);
            Toast.makeText(mContext, R.string.wifi_error, Toast.LENGTH_SHORT).show();
        }
        return true;
    }

    private boolean mayDisableTethering(boolean isChecked) {
        final int wifiApState = mWifiManager.getWifiApState();
        return isChecked && ((wifiApState == WifiManager.WIFI_AP_STATE_ENABLING) ||
            (wifiApState == WifiManager.WIFI_AP_STATE_ENABLED));
    }
}