13.2.1 为 Cassandra 定义实体类

与持久化 Mongo 时一样，选择响应式还是非响应式 Cassandra 持久化，在定义领域实体类上完全没区别。我们将使用的 Ingredient、Taco 和 TacoOrder 类，与我们在第 4 章创建的完全相同。

Cassandra 注解的 Ingredient 类如清单 13.17 所示。

清单 13.17 注解 Cassandra 持久化 Ingredient 类。

package tacos;

import org.springframework.data.cassandra.core.mapping.PrimaryKey;
import org.springframework.data.cassandra.core.mapping.Table;

import lombok.AccessLevel;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@AllArgsConstructor
@NoArgsConstructor(access=AccessLevel.PRIVATE, force=true)
@Table("ingredients")
public class Ingredient {

  @PrimaryKey
  private String id;
  private String name;
  private Type type;

  public static enum Type {
    WRAP, PROTEIN, VEGGIES, CHEESE, SAUCE
  }

}

至于 Taco 类，它是用类似的 Cassandra 持久化注解定义的，如清单 13.18 所示：

清单 13.18 为 Cassandra 持久化注解的 Taco。

package tacos;

import java.util.ArrayList;
import java.util.Date;
import java.util.List;
import java.util.UUID;

import javax.validation.constraints.NotNull;
import javax.validation.constraints.Size;

import org.springframework.data.cassandra.core.cql.Ordering;
import org.springframework.data.cassandra.core.cql.PrimaryKeyType;
import org.springframework.data.cassandra.core.mapping.Column;
import org.springframework.data.cassandra.core.mapping.PrimaryKeyColumn;
import org.springframework.data.cassandra.core.mapping.Table;
import org.springframework.data.rest.core.annotation.RestResource;

import com.datastax.oss.driver.api.core.uuid.Uuids;

import lombok.Data;

@Data
@RestResource(rel = "tacos", path = "tacos")
@Table("tacos")
public class Taco {

  @PrimaryKeyColumn(type=PrimaryKeyType.PARTITIONED)
  private UUID id = Uuids.timeBased();

  @NotNull
  @Size(min = 5, message = "Name must be at least 5 characters long")
  private String name;

  @PrimaryKeyColumn(type=PrimaryKeyType.CLUSTERED,
          ordering=Ordering.DESCENDING)
  private Date createdAt = new Date();

  @Size(min=1, message="You must choose at least 1 ingredient")
  @Column("ingredients")
  private List<IngredientUDT> ingredients = new ArrayList<>();

  public void addIngredient(Ingredient ingredient) {
    this.ingredients.add(new IngredientUDT(ingredient.getName(), ingredient.getType()));
  }
}

由于通过用户定义的类型引用对象，因此您还需要 IngreditUDT 类，如清单 13.19 所示。

清单 13.19 是 Cassandra 持久化的用户定义类型。

package tacos;

import org.springframework.data.cassandra.core.mapping.UserDefinedType;

import lombok.AccessLevel;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@AllArgsConstructor
@NoArgsConstructor(access = AccessLevel.PRIVATE, force = true)
@UserDefinedType("ingredient")
public class IngredientUDT {
  private String name;
  private Ingredient.Type type;
}

三个领域实体类中的最后一个，TacoOrder 持久化如清单 13.20 所示。

清单 13.20 为 Cassandra 持久化注解 TacoOrder。

package tacos;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
import java.util.UUID;

import org.springframework.data.cassandra.core.mapping.Column;
import org.springframework.data.cassandra.core.mapping.PrimaryKey;
import org.springframework.data.cassandra.core.mapping.Table;

import com.datastax.oss.driver.api.core.uuid.Uuids;

import lombok.Data;

@Data
@Table("tacoorders")
public class TacoOrder implements Serializable {
  private static final long serialVersionUID = 1L;

  @PrimaryKey
  private UUID id = Uuids.timeBased();
  private Date placedAt = new Date();

  @Column("user")
  private UserUDT user;

  private String deliveryName;

  private String deliveryStreet;

  private String deliveryCity;

  private String deliveryState;

  private String deliveryZip;

  private String ccNumber;

  private String ccExpiration;

  private String ccCVV;

  @Column("tacos")
  private List<TacoUDT> tacos = new ArrayList<>();

  public void addTaco(Taco taco) {
    this.addTaco(new TacoUDT(taco.getName(), taco.getIngredients()));
  }
  public void addTaco(TacoUDT tacoUDT) {
    this.tacos.add(tacoUDT);
  }
}

就像 Taco 通过用户定义的类型引用配料一样，TacoOrder 引用通过 TacoUDT 类实现 Taco，如清单 13.21 所示。

清单 13.21 Cassandra 持久化的 Taco 用户定义类型。

package tacos;

import java.util.List;

import org.springframework.data.cassandra.core.mapping.UserDefinedType;

import lombok.Data;

@Data
@UserDefinedType("taco")
public class TacoUDT {

  private final String name;
  private final List<IngredientUDT> ingredients;

}

再重复一遍，它们与非响应式的对应类是相同的。我只重复在这里把它们放了一遍，这样您就不必到其他单来记住它们的样子。

现在让我们定义保存这些对象的 Repository。