[Android5.1]系统默认设置

Posted 2022-12-04 迷途小书童Eric

settings.db

Andorid系统中设置的相关信息存放在数据库中，具体位置为：
/data/data/com.android.providers.settings/database/settings.db
该数据库就是轻量级的关系型数据库SQLite。Android对该数据库的操作封装成了许多SQLiteXXX类。framework层或应用层使用这些类就可以实现从数据库的读写操作。
那在Android系统中怎样查看settings.db中的内容呢？
其实很简单：

• adb shell进到系统中
• 运行以下命令，打开数据库

$ sqlite3 /data/data/com.android.providers.settings/database/settings.db
sqlite3>

• 使用sqlite的shell指令，查看数据库内容，内容如下：

sqlite3>.tables //列出数据库中存在的表
bluetooth_devices bookmarks secure system global

sqlite3>select * from secure; //列出表格secure中的所有内容
1|location_providers_allowed|
2|mock_location|0
3|backup_enabled|0
4|backup_transport|android/com.android.internal.backup.LocalTransport
5|mount_play_not_snd|1
6|mount_ums_autostart|0
7|mount_ums_prompt|1
8|mount_ums_notify_enabled|1
9|accessibility_script_injection|0
……
19|screensaver_components|com.android.deskclock/com.android.deskclock.Screensaver
20|screensaver_default_component|com.android.deskclock/com.android.deskclock.Screensaver
21|accessibility_display_magnification_enabled|0
22|accessibility_display_magnification_scale|2.0
23|accessibility_display_magnification_auto_update|1
25|immersive_mode_confirmations|
26|install_non_market_apps|0
27|wake_gesture_enabled|1
28|lock_screen_show_notifications|1
29|lock_screen_allow_private_notifications|1
30|sleep_timeout|-1
33|android_id|26b7afacf1a071ad
……
47|enabled_input_methods|com.android.inputmethod.latin/.LatinIME
49|input_methods_subtype_history|com.sohu.inputmethod.sogou/.SogouIME;-1
50|default_input_method|com.android.inputmethod.latin/.LatinIME

defaults.xml

Anroid系统有一些默认设置，这些默认设置就存放在defaults.xml中，路径为：

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

内容如下：

<resources>
    <bool name="def_dim_screen">true</bool>
    <integer name="def_screen_off_timeout">60000</integer>
    <integer name="def_button_light_off_timeout">1500</integer>
    <integer name="def_sleep_timeout">-1</integer>
    <bool name="def_airplane_mode_on">false</bool>
    <integer name="def_container_permission_disabled">0</integer>
    <bool name="def_theater_mode_on">false</bool>
    <!-- Comma-separated list of bluetooth, wifi, and cell. -->
    <string name="def_airplane_mode_radios" translatable="false">cell,bluetooth,wifi,nfc,wimax</string>
    <string name="airplane_mode_toggleable_radios" translatable="false">bluetooth,wifi,nfc</string>
    ...
    ...
    <string name="config_default_input_method" translatable="false">com.sohu.inputmethod.sogou/.SogouIME</string>
    <string name="config_enabled_input_method" translatable="false">com.sohu.inputmethod.sogou/.SogouIME</string>
</resources>

load settings

在手机第一次开机或恢复出厂设置时，系统会创建settings.db数据库及各个表格，然后从defaults.xml中读出默认设置并存入数据库相应的表格中。代码如下：

public class DatabaseHelper extends SQLiteOpenHelper 
    ...
    //创建secure表格
    private void createSecureTable(SQLiteDatabase db) 
        db.execSQL("CREATE TABLE secure (" +
                "_id INTEGER PRIMARY KEY AUTOINCREMENT," +
                "name TEXT UNIQUE ON CONFLICT REPLACE," +
                "value TEXT" +
                ");");
        db.execSQL("CREATE INDEX secureIndex1 ON secure (name);");
    

    //创建global表格
    private void createGlobalTable(SQLiteDatabase db) 
        db.execSQL("CREATE TABLE global (" +
                "_id INTEGER PRIMARY KEY AUTOINCREMENT," +
                "name TEXT UNIQUE ON CONFLICT REPLACE," +
                "value TEXT" +
                ");");
        db.execSQL("CREATE INDEX globalIndex1 ON global (name);");
    

    @Override
    public void onCreate(SQLiteDatabase db) 
        //创建system表格
        db.execSQL("CREATE TABLE system (" +
                    "_id INTEGER PRIMARY KEY AUTOINCREMENT," +
                    "name TEXT UNIQUE ON CONFLICT REPLACE," +
                    "value TEXT" +
                    ");");
        db.execSQL("CREATE INDEX systemIndex1 ON system (name);");

        createSecureTable(db);

        // 只有系统为单用户时，才创建global表格
        // Only create the global table for the singleton 'owner' user
        if (mUserHandle == UserHandle.USER_OWNER) 
            createGlobalTable(db);
        

        //创建 bluetooth_devices表格
        db.execSQL("CREATE TABLE bluetooth_devices (" +
                    "_id INTEGER PRIMARY KEY," +
                    "name TEXT," +
                    "addr TEXT," +
                    "channel INTEGER," +
                    "type INTEGER" +
                    ");");

        //创建bookmarks表格       
        db.execSQL("CREATE TABLE bookmarks (" +
                    "_id INTEGER PRIMARY KEY," +
                    "title TEXT," +
                    "folder TEXT," +
                    "intent TEXT," +
                    "shortcut INTEGER," +
                    "ordering INTEGER" +
                    ");");

        db.execSQL("CREATE INDEX bookmarksIndex1 ON bookmarks (folder);");
        db.execSQL("CREATE INDEX bookmarksIndex2 ON bookmarks (shortcut);");

        // Populate bookmarks table with initial bookmarks
        boolean onlyCore = false;
        try 
            onlyCore = IPackageManager.Stub.asInterface(ServiceManager.getService(
                    "package")).isOnlyCoreApps();
         catch (RemoteException e) 
        
        if (!onlyCore) 
            loadBookmarks(db);
        

        // Load initial volume levels into DB
        loadVolumeLevels(db);

        // Load inital settings values
        loadSettings(db);  //加载默认设置
     
    ...

代码比较简单，创建各种各种表格，初始化各表格中的内容。我们重点看一下loadSettings()：

private void loadSettings(SQLiteDatabase db) 
        loadSystemSettings(db);
        loadSecureSettings(db);
        // The global table only exists for the 'owner' user
        if (mUserHandle == UserHandle.USER_OWNER) 
            loadGlobalSettings(db);
        
    

可见，先后初始化了system、secure和global三个表格。这三个函数的具体实现差不多，我们以loadSystemSettings()，看一下具体做了什么：

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

        loadBooleanSetting(stmt, Settings.System.DIM_SCREEN,
                R.bool.def_dim_screen);
        loadIntegerSetting(stmt, Settings.System.SCREEN_OFF_TIMEOUT,
                R.integer.def_screen_off_timeout);

        // set default touch light timeout.
        loadIntegerSetting(stmt, Settings.System.BUTTON_LIGHT_OFF_TIMEOUT,
                R.integer.def_button_light_off_timeout);
        // Set default cdma DTMF type
        loadSetting(stmt, Settings.System.DTMF_TONE_TYPE_WHEN_DIALING, 0);

        // Set default hearing aid
        loadSetting(stmt, Settings.System.HEARING_AID, 0);

        // Set default tty mode
        loadSetting(stmt, Settings.System.TTY_MODE, 0);

        loadIntegerSetting(stmt, Settings.System.SCREEN_BRIGHTNESS,
                R.integer.def_screen_brightness);

        loadBooleanSetting(stmt, Settings.System.SCREEN_BRIGHTNESS_MODE,
                R.bool.def_screen_brightness_automatic_mode);

        ...

        loadUISoundEffectsSettings(stmt);

        loadIntegerSetting(stmt, Settings.System.POINTER_SPEED,
                R.integer.def_pointer_speed);
     finally 
        if (stmt != null) stmt.close();
    

代码也是很简单，调用sqlite语句：

INSERT OR IGNORE INTO system(name,value) VALUES(xxx,xxx);

往system表格中插入各数据项。
这里使用了“INSERT OR IGNORE INTO“，意思是，如果数据库没有该数据项，就插入新的数据；如果有，就跳过这条数据。
下面，挑其中一句代码说明：

public static final String SCREEN_OFF_TIMEOUT = "screen_off_timeout";

loadIntegerSetting(stmt, Settings.System.SCREEN_OFF_TIMEOUT,
                R.integer.def_screen_off_timeout);

R.integer.def_screen_off_timeout就是前面讲的defaults.xml中的默认设置

<integer name="def_screen_off_timeout">60000</integer>

这样，在settings.db的system表格中会存在以下表项：

12|screen_off_timeout|60000