Android 在frameworks中修改Setting中的默认值（一）

在frameworks中跟Setting默认值相关的几个文件

/frameworks/base/packages/SettingsProvider/res/values/defaults.xml

/frameworks/base/packages/SettingsProvider/src/com/android/providers/settings/DatabaseHelper.java

在defaults.xml文件中定义了相关的值，DatabaseHelper.java会把相应的值读取出来保存到ContentProvider

下面就来看下defaults.xml中定义了哪些值

    true
    60000
    false
    
    cell,bluetooth,wifi,nfc,wimax
    bluetooth,wifi,nfc
    true
    true
    true
    
    102
    false
    100%
    100%
    true

    false
    false
    false
    true
    
    gps
    true
    true
    true
    false
    
    2
    true

    false
    
    com.google.android.backup/.BackupTransportService

    
    true

    true
    false
    true
    true

    
    1
    /system/media/audio/ui/LowBattery.ogg
    0
    /system/media/audio/ui/Dock.ogg
    /system/media/audio/ui/Undock.ogg
    /system/media/audio/ui/Dock.ogg
    /system/media/audio/ui/Undock.ogg
    1
    /system/media/audio/ui/Lock.ogg
    /system/media/audio/ui/Unlock.ogg
    /system/media/audio/ui/WirelessChargingStarted.ogg

    false
    false
    1

    
    true

    
    true

    
    false

    
    false

    
    
            
            0x13=0x01000100;
            
            0x14=0x01010100;
            
            0x15=0x02000001;
            
            0x16=0x02010001;
            
            0x200000013=0x02000601;
            
            0x200000014=0x02010601;
            
            
            0x200000015=0x03020101;
            
            
            0x200000016=0x03010201;
            
            0x200000023=0x02000301;
            
            0x200000024=0x02010301;
            
            
            0x200000037=0x03070201;
            
            
            0x200000038=0x03000701:0x03010701:0x03020701;
    

    
    
        https://ssl.gstatic.com/accessibility/javascript/android/AndroidVox_v1.js
    

    
    false

    
    200%

    
    false

    
    true

    
    0

    
    -1
    
    -1

    
    500

    
    0

    
    true
    
    false

    
    false

    
    9

    
    false

    
    0

上面的xml定义中String有一个属性translatable="false"表示多国语言时不需要进行翻译，这里就不对上面的定义一一解释，只对gps进行分析

在DatabaseHelper.java中有一个函数来加载.xml中的字段

private void loadSecureSettings(SQLiteDatabase db) {
        SQLiteStatement stmt = null;
        try {
            stmt = db.compileStatement("INSERT OR IGNORE INTO secure(name,value)"
                    + " VALUES(?,?);");

           loadSetting(stmt, Settings.Secure.LOCATION_PROVIDERS_ALLOWED,
                mUtils.getStringValue(Settings.Secure.LOCATION_PROVIDERS_ALLOWED, R.string.def_location_providers_allowed));		

            String wifiWatchList = SystemProperties.get("ro.com.android.wifi-watchlist");
            if (!TextUtils.isEmpty(wifiWatchList)) {
                loadSetting(stmt, Settings.Secure.WIFI_WATCHDOG_WATCH_LIST, wifiWatchList);
            }

            // Don't do this.  The SystemServer will initialize ADB_ENABLED from a
            // persistent system property instead.
            loadSetting(stmt, Settings.Secure.ADB_ENABLED, 1);

            // Allow mock locations default, based on build
            loadSetting(stmt, Settings.Secure.ALLOW_MOCK_LOCATION,
                    "1".equals(SystemProperties.get("ro.allow.mock.location")) ? 1 : 0);

            loadSecure35Settings(stmt);

            loadBooleanSetting(stmt, Settings.Secure.MOUNT_PLAY_NOTIFICATION_SND,
                    R.bool.def_mount_play_notification_snd);

            loadBooleanSetting(stmt, Settings.Secure.MOUNT_UMS_AUTOSTART,
                    R.bool.def_mount_ums_autostart);

            loadBooleanSetting(stmt, Settings.Secure.MOUNT_UMS_PROMPT,
                    R.bool.def_mount_ums_prompt);

            loadBooleanSetting(stmt, Settings.Secure.MOUNT_UMS_NOTIFY_ENABLED,
                    R.bool.def_mount_ums_notify_enabled);

            loadBooleanSetting(stmt, Settings.Secure.ACCESSIBILITY_SCRIPT_INJECTION,
                    R.bool.def_accessibility_script_injection);

            loadStringSetting(stmt, Settings.Secure.ACCESSIBILITY_WEB_CONTENT_KEY_BINDINGS,
                    R.string.def_accessibility_web_content_key_bindings);

            loadIntegerSetting(stmt, Settings.Secure.LONG_PRESS_TIMEOUT,
                    R.integer.def_long_press_timeout_millis);

            loadBooleanSetting(stmt, Settings.Secure.TOUCH_EXPLORATION_ENABLED,
                    R.bool.def_touch_exploration_enabled);

            loadBooleanSetting(stmt, Settings.Secure.ACCESSIBILITY_SPEAK_PASSWORD,
                    R.bool.def_accessibility_speak_password);

            loadStringSetting(stmt, Settings.Secure.ACCESSIBILITY_SCREEN_READER_URL,
                    R.string.def_accessibility_screen_reader_url);

            if (SystemProperties.getBoolean("ro.lockscreen.disable.default", false) == true) {
                loadSetting(stmt, Settings.System.LOCKSCREEN_DISABLED, "1");
            } else {
                loadBooleanSetting(stmt, Settings.System.LOCKSCREEN_DISABLED,
                        R.bool.def_lockscreen_disabled);
            }

            loadBooleanSetting(stmt, Settings.Secure.SCREENSAVER_ENABLED,
                    com.android.internal.R.bool.config_dreamsEnabledByDefault);
            loadBooleanSetting(stmt, Settings.Secure.SCREENSAVER_ACTIVATE_ON_DOCK,
                    com.android.internal.R.bool.config_dreamsActivatedOnDockByDefault);
            loadBooleanSetting(stmt, Settings.Secure.SCREENSAVER_ACTIVATE_ON_SLEEP,
                    com.android.internal.R.bool.config_dreamsActivatedOnSleepByDefault);
            loadStringSetting(stmt, Settings.Secure.SCREENSAVER_COMPONENTS,
                    com.android.internal.R.string.config_dreamsDefaultComponent);
            loadStringSetting(stmt, Settings.Secure.SCREENSAVER_DEFAULT_COMPONENT,
                    com.android.internal.R.string.config_dreamsDefaultComponent);

            loadBooleanSetting(stmt, Settings.Secure.ACCESSIBILITY_DISPLAY_MAGNIFICATION_ENABLED,
                    R.bool.def_accessibility_display_magnification_enabled);

            loadFractionSetting(stmt, Settings.Secure.ACCESSIBILITY_DISPLAY_MAGNIFICATION_SCALE,
                    R.fraction.def_accessibility_display_magnification_scale, 1);

            loadBooleanSetting(stmt,
                    Settings.Secure.ACCESSIBILITY_DISPLAY_MAGNIFICATION_AUTO_UPDATE,
                    R.bool.def_accessibility_display_magnification_auto_update);

            loadBooleanSetting(stmt, Settings.Secure.USER_SETUP_COMPLETE,
                    R.bool.def_user_setup_complete);

            mUtils.loadCustomSecureSettings(stmt);

        } finally {
            if (stmt != null) stmt.close();
        }
    }

在上面的代码中有

loadSetting(stmt, Settings.Secure.LOCATION_PROVIDERS_ALLOWED,
mUtils.getStringValue(Settings.Secure.LOCATION_PROVIDERS_ALLOWED, R.string.def_location_providers_allowed));去加载字符串，保存到数据库中，数据库名称为：

private static final String DATABASE_NAME = "settings.db";

static String dbNameForUser(final int userHandle) {
        // The owner gets the unadorned db name;
        if (userHandle == UserHandle.USER_OWNER) {
            return DATABASE_NAME;
        } else {
            // Place the database in the user-specific data tree so that it's
            // cleaned up automatically when the user is deleted.
            File databaseFile = new File(
                    Environment.getUserSystemDirectory(userHandle), DATABASE_NAME);
            return databaseFile.getPath();
        }
    }

    public DatabaseHelper(Context context, int userHandle) {
        super(context, dbNameForUser(userHandle), null, DATABASE_VERSION);
        mContext = context;
        mUserHandle = userHandle;
    }

来看下是如何读取ContentProvider中的数据，在Setting中就可以使用getContentResolver()去查询对应的字段

当然并不是所有的默认值都是通过读取defaults.xml的，也有的是在DatabaseHelper.java中直接设置

如loadSetting(stmt, Settings.Secure.ADB_ENABLED, 1);  这个ADB Debugging开关就是直接在数据库文件中写入的。

关于USB Debugging 开关也可以在systemui的systemui/usb/StorageNotification.java文件中去设置，可以判断是否有IMEI号

分析代码时如果发现在defaults.xml找不到这一项就直接在DatabaseHelper.java文件中查找。