1 手动搜网应用程序

1.1 MobileNetworkSettings入口

我们首先从apk的Manifest找入口，如下：
/packages/apps/Settings/AndroidManifest.xml

        <activity android:name=".network.telephony.MobileNetworkActivity"
                  android:label="@string/network_settings_title"
                  android:exported="true"
                  android:launchMode="singleTask">
            <intent-filter android:priority="1">
                <!-- Displays the MobileNetworkActivity and opt-in dialog for capability discovery. -->
                <action android:name="android.telephony.ims.action.SHOW_CAPABILITY_DISCOVERY_OPT_IN" />
                <action android:name="android.settings.NETWORK_OPERATOR_SETTINGS" />
                <action android:name="android.settings.DATA_ROAMING_SETTINGS" />
                <action android:name="android.settings.MMS_MESSAGE_SETTING" />
                <category android:name="android.intent.category.DEFAULT" />
            </intent-filter>
        </activity>

紧接着的调用关系，会使用到布局xml文件：
/packages/apps/Settings/src/com/android/settings/network/telephony/MobileNetworkActivity.java
/packages/apps/Settings/src/com/android/settings/network/telephony/MobileNetworkSettings.java

    @Override
    protected int getPreferenceScreenResId() {
        return R.xml.mobile_network_settings;
    }

1.1.1 MobileNetworkSettings布局

从上述的R.xml.mobile_network_settings引入布局，这里摘抄部分：
/packages/apps/Settings/res/xml/mobile_network_settings.xml

<PreferenceScreen
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:settings="http://schemas.android.com/apk/res-auto"
    android:key="mobile_network_pref_screen">

    <com.android.settings.widget.SettingsMainSwitchPreference
        android:key="use_sim_switch"
        settings:controller="com.android.settings.network.telephony.MobileNetworkSwitchController"/>

    <PreferenceCategory
        android:key="enabled_state_container"
        android:title="@string/summary_placeholder"
        settings:controller="com.android.settings.network.telephony.DisabledSubscriptionController"
        android:layout="@layout/preference_category_no_label">

        <SwitchPreference
            android:key="mobile_data_enable"
            android:title="@string/mobile_data_settings_title"
            android:summary="@string/mobile_data_settings_summary"
            settings:controller="com.android.settings.network.telephony.MobileDataPreferenceController"
            settings:allowDividerAbove="true"/>

        <com.android.settingslib.RestrictedSwitchPreference
            android:key="button_roaming_key"
            android:title="@string/roaming"
            android:persistent="false"
            android:summaryOn="@string/roaming_enable"
            android:summaryOff="@string/roaming_disable"
            settings:userRestriction="no_data_roaming"
            settings:controller="com.android.settings.network.telephony.RoamingPreferenceController"/>

        <SwitchPreference
            android:key="carrier_wifi_toggle"
            android:title="@string/carrier_wifi_offload_title"
            android:summary="@string/carrier_wifi_offload_summary"
            settings:controller="com.android.settings.network.CarrierWifiTogglePreferenceController"/>

        <Preference
            android:key="carrier_wifi_network"
            android:title="@string/carrier_wifi_network_title"
            android:selectable="false"
            settings:searchable="false"/>

        <SwitchPreference
            android:key="4g_calling"
            android:title="@string/enhanced_4g_lte_mode_title_4g_calling"
            android:persistent="false"
            android:summary="@string/enhanced_4g_lte_mode_summary_4g_calling"
            settings:keywords="@string/keywords_enhance_4g_lte"
            settings:controller="com.android.settings.network.telephony.Enhanced4gCallingPreferenceController"/>
        
        <ListPreference
            android:key="preferred_network_mode_key"
            android:title="@string/preferred_network_mode_title"
            android:summary="@string/preferred_network_mode_summary"
            android:entries="@array/preferred_network_mode_choices"
            android:entryValues="@array/preferred_network_mode_values"
            android:dialogTitle="@string/preferred_network_mode_dialogtitle"
            settings:controller="com.android.settings.network.telephony.PreferredNetworkModePreferenceController"/>

        <PreferenceCategory
            android:key="network_operators_category_key"
            android:title="@string/network_operator_category"
            settings:controller="com.android.settings.network.telephony.NetworkPreferenceCategoryController">

            <SwitchPreference
                android:key="auto_select_key"
                android:title="@string/select_automatically"
                settings:controller="com.android.settings.network.telephony.gsm.AutoSelectPreferenceController"/>

            <Preference
                android:key="choose_network_key"
                android:title="@string/choose_network_title"
                android:fragment="com.android.phone.NetworkSelectSetting"
                settings:controller="com.android.settings.network.telephony.gsm.OpenNetworkSelectPagePreferenceController"/>
        </PreferenceCategory>

        <!--We want separate APN setting from reset of settings because we want user to change it with caution-->
        <com.android.settingslib.RestrictedPreference
            android:key="telephony_apn_key"
            android:persistent="false"
            android:title="@string/mobile_network_apn_title"
            settings:allowDividerAbove="true"
            settings:controller="com.android.settings.network.telephony.ApnPreferenceController"/>
        
</PreferenceScreen>

1.1.2 MobileNetworkSettings字符串位置

通过字符串也可以快速查找一些难以确认的界面程序入口：
/packages/apps/Settings/res/values/strings.xml

1.1.3 MobileNetworkSettings初始化

在onAttach进行一些初步的初始化：
/packages/apps/Settings/src/com/android/settings/network/telephony/MobileNetworkSettings.java

    @Override
    public void onAttach(Context context) {
        super.onAttach(context);

        use(MobileNetworkSwitchController.class).init(getLifecycle(), mSubId);
        use(DisabledSubscriptionController.class).init(getLifecycle(), mSubId);
        use(MobileDataPreferenceController.class).init(getFragmentManager(), mSubId);
        use(MobileDataPreferenceController.class).setWifiPickerTrackerHelper(
                new WifiPickerTrackerHelper(getSettingsLifecycle(), context,
                        null /* WifiPickerTrackerCallback */));
        use(RoamingPreferenceController.class).init(getFragmentManager(), mSubId);
        use(ApnPreferenceController.class).init(mSubId);
        use(PreferredNetworkModePreferenceController.class).init(mSubId);
        use(CarrierWifiTogglePreferenceController.class).init(getLifecycle(), mSubId);

        final WifiCallingPreferenceController wifiCallingPreferenceController =
                use(WifiCallingPreferenceController.class).init(mSubId);

        final OpenNetworkSelectPagePreferenceController openNetworkSelectPagePreferenceController =
                use(OpenNetworkSelectPagePreferenceController.class).init(getLifecycle(), mSubId);
        final AutoSelectPreferenceController autoSelectPreferenceController =
                use(AutoSelectPreferenceController.class)
                        .init(getLifecycle(), mSubId)
                        .addListener(openNetworkSelectPagePreferenceController);
        use(NetworkPreferenceCategoryController.class).init(getLifecycle(), mSubId)
                .setChildren(Arrays.asList(autoSelectPreferenceController));

        use(NetworkPreferenceCategoryController.class).init(getLifecycle(), mSubId)
                .setChildren(Arrays.asList(autoSelectPreferenceController));
        use(Enhanced4gCallingPreferenceController.class).init(mSubId)
                .addListener(videoCallingPreferenceController);

1.2 手动搜网代码入口

从上述分析可以得知，手动搜网的代码入口java文件如下：
/packages/apps/Settings/src/com/android/settings/network/telephony/gsm/AutoSelectPreferenceController.java

1.3 手动搜网应用流程

如果用户选择了手动搜网，则走else流程：
/packages/apps/Settings/src/com/android/settings/network/telephony/gsm/AutoSelectPreferenceController.java

    @Override
    public boolean setChecked(boolean isChecked) {
        if (isChecked) {
            setAutomaticSelectionMode();
            return false;
        } else {
            final Bundle bundle = new Bundle();
            bundle.putInt(Settings.EXTRA_SUB_ID, mSubId);
            new SubSettingLauncher(mContext)
                    .setDestination(NetworkSelectSettings.class.getName())
                    .setSourceMetricsCategory(SettingsEnums.MOBILE_NETWORK_SELECT)
                    .setTitleRes(R.string.choose_network_title)
                    .setArguments(bundle)
                    .launch();
            return false;
        }
    }

如下界面被发起，startNetworkQuery()被调用。mUseNewApi来自config_enableNewAutoSelectNetworkUI，该值为false，所以选择了NETWORK_SCAN_TYPE_WAIT_FOR_ALL_RESULTS：
/packages/apps/Settings/src/com/android/settings/network/telephony/NetworkSelectSettings.java

    @Override
    public void onStart() {
        super.onStart();

        updateForbiddenPlmns();
        if (isProgressBarVisible()) {
            return;
        }
        if (mWaitingForNumberOfScanResults <= 0) {
            startNetworkQuery();
        }
    }

    private void startNetworkQuery() {
        setProgressBarVisible(true);
        if (mNetworkScanHelper != null) {
            mRequestIdManualNetworkScan = getNewRequestId();
            mWaitingForNumberOfScanResults = MIN_NUMBER_OF_SCAN_REQUIRED;
            mNetworkScanHelper.startNetworkScan(
                    mUseNewApi
                            ? NetworkScanHelper.NETWORK_SCAN_TYPE_INCREMENTAL_RESULTS
                            : NetworkScanHelper.NETWORK_SCAN_TYPE_WAIT_FOR_ALL_RESULTS);
        }
    }

接下来通过startNetworkScan()来启动手动搜网，走该代码的if分支，逐步完成对TelephonyManager API的调用。这里也需要注意，对于网络侧返回信息，则callback函数onSuccess()或onFailure()会被调用：
/packages/apps/Settings/src/com/android/settings/network/telephony/NetworkScanHelper.java

    /**
     * Performs a network scan for the given type {@code type}.
     * {@link #NETWORK_SCAN_TYPE_INCREMENTAL_RESULTS} is recommended if modem supports
     * {@link TelephonyManager#requestNetworkScan(
     * NetworkScanRequest, Executor, TelephonyScanManager.NetworkScanCallback)}.
     *
     * @param type used to tell which network scan API should be used.
     */
    public void startNetworkScan(@NetworkQueryType int type) {
        if (type == NETWORK_SCAN_TYPE_WAIT_FOR_ALL_RESULTS) {
            mNetworkScanFuture = SettableFuture.create();
            Futures.addCallback(mNetworkScanFuture, new FutureCallback<List<CellInfo>>() {
                @Override
                public void onSuccess(List<CellInfo> result) {
                    onResults(result);
                    onComplete();
                }

                @Override
                public void onFailure(Throwable t) {
                    if (t instanceof CancellationException) {
                        return;
                    }
                    int errCode = Integer.parseInt(t.getMessage());
                    onError(errCode);
                }
            }, MoreExecutors.directExecutor());
            mExecutor.execute(new NetworkScanSyncTask(
                    mTelephonyManager, (SettableFuture) mNetworkScanFuture));
        } else if (type == NETWORK_SCAN_TYPE_INCREMENTAL_RESULTS) {
            if (mNetworkScanRequester != null) {
                return;
            }
            mNetworkScanRequester = mTelephonyManager.requestNetworkScan(
                    createNetworkScanForPreferredAccessNetworks(),
                    mExecutor,
                    mInternalNetworkScanCallback);
            if (mNetworkScanRequester == null) {
                onError(NetworkScan.ERROR_RADIO_INTERFACE_ERROR);
            }
        }
    }

    private static final class NetworkScanSyncTask implements Runnable {
        private final SettableFuture<List<CellInfo>> mCallback;
        private final TelephonyManager mTelephonyManager;

        NetworkScanSyncTask(
                TelephonyManager telephonyManager, SettableFuture<List<CellInfo>> callback) {
            mTelephonyManager = telephonyManager;
            mCallback = callback;
        }

        @Override
        public void run() {
            final CellNetworkScanResult result = mTelephonyManager.getAvailableNetworks();
            if (result.getStatus() == CellNetworkScanResult.STATUS_SUCCESS) {
                final List<CellInfo> cellInfos = result.getOperators()
                        .stream()
                        .map(operatorInfo
                                -> CellInfoUtil.convertOperatorInfoToCellInfo(operatorInfo))
                        .collect(Collectors.toList());
                Log.d(TAG, "Sync network scan completed, cellInfos = "
                        + CellInfoUtil.cellInfoListToString(cellInfos));
                mCallback.set(cellInfos);
            } else {
                final Throwable error = new Throwable(
                        Integer.toString(convertToScanErrorCode(result.getStatus())));
                mCallback.setException(error);
                Log.d(TAG, "Sync network scan error, ex = " + error);
            }
        }
    }

2 手动搜网Framework

2.1 Framework涉及到的类

frame_class.png

四个主要的类：
TelephonyManager : 提供API给应用。
PhoneInterfaceManager : 实现ITelephony接口，实现对Phone的控制操作。其内部类MainThreadHandler继承于Handler。
GsmCdmaPhone : Phone，其父类继承于Handler。
RIL : RILJ，提供API给Phone

2.2 流程图

这些类的工作流程一般如下：

getAvailableNetworks_framework.png

Step1: 通过TelephonyManager API调用Telephony Service(PhoneInterfaceManager)
Step2: 通过Telephony Service调用控制Phone
Step3: 通过Phone调用RILJ
Step4: RILJ通过HIDL实现对RILD的调用
Step5: RILD通过RadioResponse把返回值反馈给Phone
Step6: Phone把返回值传给Telephony Service
Step7: Telephony Service把返回值通知给应用程序

3 手动搜网RILD

3.1 流程图

rild.png

3.2 AT Command

可参考3GPP TS 27.007之7.3 PLMN selection +COPS
如下是联通卡搜网的一个结果示例：

AT> AT+COPS=?
AT< +COPS: (1,"China Unicom","CU-GSM","46001","25C7",7),(1,"China Unicom","CU-GSM","46001","A5AB",2),(2,"China Unicom","CU-GSM","46001","77B600",11),(3,"46011","46011","46011","7C06",7),(3,"China Mobile","CMCC","46000","2441",7),(3,"46011","46011","46011","77B600",11),,(0-3),(0-2)
AT< OK

界面效果如下：
China Unicom 4G (Available)
China Unicom 3G (Available)
China Unicom 5G (Current)
China Telecom 4G (Forbidden)
China Mobile 4G (Forbidden)
China Telecom 5G (Forbidden)

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本文链接：https://www.jianshu.com/p/e56e83ca520d

Android S源码手动搜网流程