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：

./packages/SettingsProvider/res/values/defaults.xml:40:    <bool name="def_wifi_display_on">false</bool>

然后在DatabaseHelper.java中创建完数据库进行默认值的插入

./packages/SettingsProvider/src/com/android/providers/settings/DatabaseHelper.java:2559:            loadBooleanSetting(stmt, Settings.Global.WIFI_DISPLAY_ON,R.bool.def_wifi_display_on);

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 loadSettings(SQLiteDatabase db) {
        loadSystemSettings(db);
        loadSecureSettings(db);
        // The global table only exists for the \'owner/system\' user
        if (mUserHandle == UserHandle.USER_SYSTEM) {
            loadGlobalSettings(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);
            ......
}

发表于

2018-10-18 17:52

寒风@

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