我在代碼中有一些字符串常量。我可以將所有這些都放入資源中嗎strings.xml?我認(rèn)為單獨(dú)使用列名的可能性仍然存在。有必要在以后對(duì)數(shù)據(jù)庫(kù)的請(qǐng)求中搜索帖子索引。不使用索引,數(shù)字會(huì)令人困惑、不舒服。private static final String NAME_DB = "cars.db";private static final String TABLE_NAME = "cars";private static final String COL_BRAND = "brand";private static final String COL_MODEL = "model";private static final String COL_COLOR = "color";private static final String COL_MAX_SPEED = "max_speed";private static final String COL_ENGINE_POWER = "engine_power";private static final String CREATE_TABLE = "CREATE TABLE IF NOT EXISTS " + TABLE_NAME + " (" + "id INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL," + COL_BRAND + " TEXT NOT NULL, " + COL_MODEL + " TEXT NOT NULL, " + COL_COLOR + " TEXT, " + COL_MAX_SPEED + " INTEGER," + COL_ENGINE_POWER + " INTEGER)";private static final String INSERT_DEFAULT_VALUES = "INSERT INTO " + TABLE_NAME + "(brand, model, color, max_speed, engine_power) VALUES" + "('Audi', 'Q7 II', 'White', 233, 252)," + "('Acura', 'ZDX', 'Black', 241, 300)," + "('BMW', 'X1 I', 'Blue', 205, 204)," + "('Hyundai', 'Solaris', 'Red', 100, 100)," + "('Hyundai', 'Tucson', 'Gray', 150, 177)," + "('BMW', '8 G14', 'Black', 250, 320)";private static final String SELECT_ALL = "SELECT * FROM " + TABLE_NAME;private static final String SELECT_TOP_1 = "SELECT * FROM " + TABLE_NAME + " LIMIT 1";示例代碼DatabaseAdapter(Context context) { db = context.openOrCreateDatabase(NAME_DB, MODE_PRIVATE, null); db.execSQL(CREATE_TABLE); Cursor cursor = db.rawQuery(SELECT_TOP_1, null); if (!cursor.moveToFirst()) { db.execSQL(INSERT_DEFAULT_VALUES); }}String[] selectAll() { Cursor cursor = db.rawQuery(SELECT_ALL, null); if (!cursor.moveToFirst()) { return null; }
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明月笑刀無(wú)情
TA貢獻(xiàn)1828條經(jīng)驗(yàn) 獲得超4個(gè)贊
有一些使用 XML 中的 SQL 的解決方案??纯茨闶欠窨梢允褂闷渲兄弧?/p>
然而,恕我直言,最好集中代碼并將文本保留在那里,甚至沒有常量。
單獨(dú)關(guān)注:數(shù)據(jù)庫(kù)查詢和結(jié)果對(duì)象。這可以通過提供低級(jí)結(jié)果集對(duì)象的 Stream 來(lái)完成,使用類可以映射到它們自己的類。解耦類;保持各層分離。(在 Android 上可能沒那么有趣。)使用代碼變得非常緊湊,查詢?cè)谄渌胤健?/p>
我的論點(diǎn):
減少來(lái)回跳轉(zhuǎn)到不同來(lái)源的次數(shù)
更好的可讀性
列名不變
常量大寫的可讀性較差
將代碼放在一起可以防止類似的查詢?cè)跓o(wú)人值守的情況下傳播
然而,在更高級(jí)別的業(yè)務(wù)代碼中它仍然比 SQL 更好,將 SQL 隔離在 XML 中以在其他地方獲得更小的源和查詢。所以至少要這樣做。
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