java从Room数据库中的模型对象存储什么

1 周，3 日 Questions & Answers 1907

我有三节POJO课Recipe、Ingredient和Step

我希望能够在离线时浏览我的食谱，所以我决定使用Room

食谱。班级

@Entity(tableName = "recipe")
public class Recipe implements Parcelable {

   @PrimaryKey(autoGenerate = false)
   @SerializedName("id")
   public int recipeId;

   @ColumnInfo(name = "recipe_name")
   public String name;

   @TypeConverters(Converters.class)
   public List<Ingredient> ingredients = null;

   @TypeConverters(Converters.class)
   public List<Step> steps = null;

   @ColumnInfo(name = "recipe_servings")
   public int servings;

   @Ignore
   public String image;

  public Recipe(int recipeId, String name, List<Ingredient> ingredients, List<Step> steps, int servings, String image) {
    this.recipeId = recipeId;
    this.name = name;
    this.ingredients = ingredients;
    this.steps = steps;
    this.servings = servings;
    this.image = image;
}
...
//getters and setters
...

转换器。班级

public class Converters {

    static Gson gson = new Gson();

    @TypeConverter
    public static List<Ingredient> stringToIngredientList(String data) {
        if (data == null) {
            return Collections.emptyList();
        }

        Type listType = new TypeToken<List<Ingredient>>() {}.getType();

        return gson.fromJson(data, listType);
    }

    @TypeConverter
    public static String ingredientListToString(List<Ingredient> ingredients) {
        return gson.toJson(ingredients);
    }

    @TypeConverter
    public static List<Step> stringToStepList(String data) {
        if (data == null) {
            return Collections.emptyList();
        }

        Type listType = new TypeToken<List<Step>>() {}.getType();

        return gson.fromJson(data, listType);
    }

    @TypeConverter
    public static String stepListToString(List<Step> steps) {
        return gson.toJson(steps);
    }
}

往复式数据库。班级

@Database(entities = {Recipe.class}, version = 1)
abstract class RecipeDatabase extends RoomDatabase {

    private static RecipeDatabase INSTANCE;

    public abstract RecipeDao recipeDao();

    public static RecipeDatabase getRecipeDatabase(Context context) {
        if (INSTANCE == null) {
            INSTANCE =
                    Room.databaseBuilder(context.getApplicationContext(), RecipeDatabase.class, "recipe-database")
                        // allow queries on the main thread.
                        // Don't do this on a real app! See PersistenceBasicSample for an example.
                        .allowMainThreadQueries()
                        .build();
        }
        return INSTANCE;
    }

    public static void destroyInstance() {
        INSTANCE = null;
    }
 }

回复。班级

@Dao
public interface RecipeDao {

    @Query("SELECT * FROM recipe")
    List<Recipe> getAll();

    @Query("SELECT * FROM recipe where recipe_name LIKE  :name")
    Recipe findByName(String name);

    @Query("SELECT COUNT(*) from recipe")
    int countRecipes();

    @Update
    void update(Recipe... recipes);

    @Insert
    void insertAll(Recipe... recipes);

    @Delete
    void delete(Recipe recipe);
}

我的问题：在使用Converters类将List<Step>和List<Ingredient>保存为Strings之后，我是否还应该保存我的每个步骤的数据库。分类和成分。类？我是否也应该为这些类包含@Entity注释？我应该做一个StepDatabase和一个IngredientDatabase吗？离线时也需要访问我的Recipes吗

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java从Room数据库中的模型对象存储什么

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