android settings源代碼分析（1）

1.android settings源碼的source code路徑爲：

kikat_4.4_CTS\packages\apps\Settings

 

2.settings主界面UI佈局

Settings的啓動類爲：

/**
 * Top-level settings activity to handle single pane and double pane UI layout.
 */
public class Settings extends PreferenceActivity
        implements ButtonBarHandler, OnAccountsUpdateListener

從繼承關係可以看出，Settings類繼承於PreferenceActivity，因此具有Preference的一些屬性和結構。

 

從Google  settings的UI看出，左邊是一些tab，右邊是tab對應的內容，那麼這些tab以及tab對應的內容主要是什麼，以及如何顯示的呢？

 

對於tab的顯示，對應的code爲：

 /**
     * Populate the activity with the top-level headers.
     */
    @Override
    public void onBuildHeaders(List<Header> headers) {
        if (!onIsHidingHeaders()) {
            loadHeadersFromResource(R.xml.settings_headers, headers);
            updateHeaderList(headers);
        }
    }

可以看出，左邊的tab實際是一些Header，從settings_headers.xml中獲取這些header。settings_header.xml對應的code爲：

<?xml version="1.0" encoding="utf-8"?>
<!-- Copyright (C) 2010 The Android Open Source Project

     Licensed under the Apache License, Version 2.0 (the "License");
     you may not use this file except in compliance with the License.
     You may obtain a copy of the License at

          http://www.apache.org/licenses/LICENSE-2.0

     Unless required by applicable law or agreed to in writing, software
     distributed under the License is distributed on an "AS IS" BASIS,
     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     See the License for the specific language governing permissions and
     limitations under the License.
-->

<preference-headers
        xmlns:android="http://schemas.android.com/apk/res/android">


    <!-- WIRELESS and NETWORKS -->
    <header android:id="@+id/wireless_section"
        android:title="@string/header_category_wireless_networks" />

    <!-- Wifi -->
    <!-- MStar Android Patch Begin -->
    <header
        android:id="@+id/wifi_settings"
        android:fragment="com.android.settings.wifi.TvWifiSettings"
        android:title="@string/wifi_settings_title"
        android:icon="@drawable/ic_settings_wireless" />
    <!-- MStar Android Patch End -->

    <!-- Ethernet -->
    <header
        android:id="@+id/ethernet_settings"
        android:fragment="com.android.settings.ethernet.EthernetSettings"
        android:title="@string/ethernet_status_title"
        android:icon="@drawable/ic_settings_ethernet" />

    <!-- Bluetooth -->
    <header
        android:id="@+id/bluetooth_settings"
        android:fragment="com.android.settings.bluetooth.TvBluetoothSettings"
        android:title="@string/bluetooth_settings_title"
        android:icon="@drawable/ic_settings_bluetooth2" />

    <!-- Data Usage -->
    <header
        android:id="@+id/data_usage_settings"
        android:fragment="com.android.settings.DataUsageSummary"
        android:title="@string/data_usage_summary_title"
        android:icon="@drawable/ic_settings_data_usage" />

    <!-- Operator hook -->
    <header
        android:fragment="com.android.settings.WirelessSettings"
        android:id="@+id/operator_settings">
        <intent android:action="com.android.settings.OPERATOR_APPLICATION_SETTING" />
    </header>

    <!-- Other wireless and network controls -->
    <header
        android:id="@+id/wireless_settings"
        android:title="@string/radio_controls_title"
        android:breadCrumbTitle="@string/wireless_networks_settings_title"
        android:fragment="com.android.settings.WirelessSettings"
        android:icon="@drawable/empty_icon" />

    <!-- DEVICE -->
    <header android:id="@+id/device_section"
        android:title="@string/header_category_device" />

    <!-- Home -->
    <header
        android:id="@+id/home_settings"
        android:icon="@drawable/ic_settings_home"
        android:fragment="com.android.settings.HomeSettings"
        android:title="@string/home_settings" />

    <!-- Sound -->
    <header
        android:id="@+id/sound_settings"
        android:icon="@drawable/ic_settings_sound"
        android:fragment="com.android.settings.SoundSettings"
        android:title="@string/sound_settings" />

    <!-- Display -->
    <header
        android:id="@+id/display_settings"
        android:icon="@drawable/ic_settings_display"
        android:fragment="com.android.settings.DisplaySettings"
        android:title="@string/display_settings" />

    <!-- Storage -->
    <header
        android:id="@+id/storage_settings"
        android:fragment="com.android.settings.deviceinfo.Memory"
        android:icon="@drawable/ic_settings_storage"
        android:title="@string/storage_settings" />

    <!-- Battery -->
    <header
        android:id="@+id/battery_settings"
        android:fragment="com.android.settings.fuelgauge.PowerUsageSummary"
        android:icon="@drawable/ic_settings_battery"
        android:title="@string/power_usage_summary_title" />

    <!-- Application Settings -->
    <header
        android:fragment="com.android.settings.applications.ManageApplications"
        android:icon="@drawable/ic_settings_applications"
        android:title="@string/applications_settings"
        android:id="@+id/application_settings" />

    <!-- Manage users -->
    <header
        android:fragment="com.android.settings.users.UserSettings"
        android:icon="@drawable/ic_settings_multiuser"
        android:title="@string/user_settings_title"
        android:id="@+id/user_settings" />

    <!-- Manage NFC payment apps -->
    <header
        android:fragment="com.android.settings.nfc.PaymentSettings"
        android:icon="@drawable/ic_settings_nfc_payment"
        android:title="@string/nfc_payment_settings_title"
        android:id="@+id/nfc_payment_settings" />

    <!-- Manufacturer hook -->
    <header
        android:fragment="com.android.settings.WirelessSettings"
        android:id="@+id/manufacturer_settings">
        <intent android:action="com.android.settings.MANUFACTURER_APPLICATION_SETTING" />
    </header>

    <!-- PERSONAL -->
    <header android:id="@+id/personal_section"
        android:title="@string/header_category_personal" />

    <!-- Location -->
    <header
        android:fragment="com.android.settings.location.LocationSettings"
        android:icon="@drawable/ic_settings_location"
        android:title="@string/location_settings_title"
        android:id="@+id/location_settings" />

    <!-- Security -->
    <header
        android:fragment="com.android.settings.SecuritySettings"
        android:icon="@drawable/ic_settings_security"
        android:title="@string/security_settings_title"
        android:id="@+id/security_settings" />

    <!-- Language -->
    <header
        android:id="@+id/language_settings"
        android:fragment="com.android.settings.inputmethod.InputMethodAndLanguageSettings"
        android:icon="@drawable/ic_settings_language"
        android:title="@string/language_settings" />

    <!-- Backup and reset -->
    <header
        android:fragment="com.android.settings.PrivacySettings"
        android:icon="@drawable/ic_settings_backup"
        android:title="@string/privacy_settings"
        android:id="@+id/privacy_settings" />

    <!-- @Patch: GTV specific changes -->
    <!-- MStar Android Patch Begin -->
    <!-- Update -->
    <header
        android:id="@+id/update_settings"
        android:fragment="com.android.settings.update.UpdateSettings"
        android:title="@string/update_settings" />
    <!-- MStar Android Patch End -->

    <!--  ACCOUNTS section -->
    <header
            android:id="@+id/account_settings"
            android:title="@string/account_settings" />

    <header
            android:id="@+id/account_add"
            android:title="@string/add_account_label"
            android:icon="@drawable/ic_menu_add_dark">
        <intent
            android:action="android.settings.ADD_ACCOUNT_SETTINGS"/>
    </header>

    <!-- SYSTEM -->
    <header android:id="@+id/system_section"
        android:title="@string/header_category_system" />

    <!-- Date & Time -->
    <header
        android:id="@+id/date_time_settings"
        android:fragment="com.android.settings.DateTimeSettings"
        android:icon="@drawable/ic_settings_date_time"
        android:title="@string/date_and_time_settings_title" />

    <!-- Accessibility feedback -->
    <header
        android:id="@+id/accessibility_settings"
        android:fragment="com.android.settings.accessibility.AccessibilitySettings"
        android:icon="@drawable/ic_settings_accessibility"
        android:title="@string/accessibility_settings" />

    <!-- Print -->
    <header
        android:id="@+id/print_settings"
        android:fragment="com.android.settings.print.PrintSettingsFragment"
        android:icon="@*android:drawable/ic_print"
        android:title="@string/print_settings" />

    <!-- Development -->
    <header
        android:id="@+id/development_settings"
        android:fragment="com.android.settings.DevelopmentSettings"
        android:icon="@drawable/ic_settings_development"
        android:title="@string/development_settings_title" />

    <!-- About Device -->
    <header
        android:id="@+id/about_settings"
        android:fragment="com.android.settings.DeviceInfoSettings"
        android:icon="@drawable/ic_settings_about"
        android:title="@string/about_settings" />

</preference-headers>

從上述xml可以看出，header的內容是通過fragment來顯示，定義了每一個header對應的fragment。

 

在private void updateHeaderList(List<Header> target)函數中，會根據當前平臺是否支持某項feature，決定是否顯示對應的header：

 else if (id == R.id.wifi_settings) {
                // Remove WiFi Settings if WiFi service is not available.
                if (!getPackageManager().hasSystemFeature(PackageManager.FEATURE_WIFI)) {
                    target.remove(i);
                }
            } else if (id == R.id.bluetooth_settings) {
                // Remove Bluetooth Settings if Bluetooth service is not available.
                if (!getPackageManager().hasSystemFeature(PackageManager.FEATURE_BLUETOOTH)) {
                    target.remove(i);
                }
            }