android - Room Android - 如何处理数据库版本升级

Question

我正在阅读有关 Android 体系结构组件 Room 的文章，想知道 Room 中是否有与可用的 SQLiteOpenHelper 方法中的 onUpgrade 等效的内容。

@Override
 public void onUpgrade(final SQLiteDatabase database, final int oldVersion, final int newVersion) {}

Answer 1

您可以使用 https://developer.android.com/training/data-storage/room/migrating-db-versions.html

 Room.databaseBuilder(getApplicationContext(), MyDb.class, "database-name")
            .addMigrations(MIGRATION_1_2,MIGRATION_1_3, MIGRATION_2_3).build();

    static final Migration MIGRATION_1_2 = new Migration(1, 2) {
        @Override
        public void migrate(SupportSQLiteDatabase database) {
            database.execSQL("CREATE TABLE `Fruit` (`id` INTEGER, "
                    + "`name` TEXT, PRIMARY KEY(`id`))");
        }
    };

    static final Migration MIGRATION_2_3 = new Migration(2, 3) {
        @Override
        public void migrate(SupportSQLiteDatabase database) {
            database.execSQL("ALTER TABLE Book "
                    + " ADD COLUMN pub_year INTEGER");
        }
    };

   static final Migration MIGRATION_1_3 = new Migration(1, 3) {
            @Override
            public void migrate(SupportSQLiteDatabase database) {
                database.execSQL("ALTER TABLE Book "
                        + " ADD COLUMN pub_year INTEGER");
            }
        };