Android中Settings默认值的设置

设置Settings的默认值有两种方式

A. 在获取是有一个接口可以进行默认值设置，当数据库中查询不到该值时，就会返回传入的默认值。

public static int getInt(ContentResolver cr, String name, int def) {            return getIntForUser(cr, name, def, cr.getUserId());        }

其中int def就是要写入的默认值。

B. 在SettingProvider中进行设置，也就是写入到数据库中

首先，在SettingsProvider/res/values/defaults.xml中写入Settings中的值对应的默认值，例如：

然后在DatabaseHelper.java中创建完数据库进行默认值的插入

该插入的流程为：

onCreate(SQLiteDatabase db) -> loadSettings(db) -> loadSystemSettings(db);loadSecureSettings(db);loadGlobalSettings(db);

源码如下：

public void onCreate(SQLiteDatabase db) {        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);

        // Only create the global table for the singleton 'owner/system' user        if (mUserHandle == UserHandle.USER_SYSTEM) {            createGlobalTable(db);        }

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

        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);    }

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

            // --- Previously in 'system'            loadBooleanSetting(stmt, Settings.Global.AIRPLANE_MODE_ON,                    R.bool.def_airplane_mode_on);

            loadBooleanSetting(stmt, Settings.Global.THEATER_MODE_ON,                    R.bool.def_theater_mode_on);

            loadStringSetting(stmt, Settings.Global.AIRPLANE_MODE_RADIOS,                    R.string.def_airplane_mode_radios);

            loadStringSetting(stmt, Settings.Global.AIRPLANE_MODE_TOGGLEABLE_RADIOS,                    R.string.airplane_mode_toggleable_radios);

            loadBooleanSetting(stmt, Settings.Global.ASSISTED_GPS_ENABLED,                    R.bool.assisted_gps_enabled); ..... loadBooleanSetting(stmt, Settings.Global.WIFI_DISPLAY_ON,                    R.bool.def_wifi_display_on); ......}