Java 如何使用CriteriaAPI构建一个动态查询，其中添加到日期的天数，并将该日期与另一个日期进行比较？

我有一张a桌和一张B桌。

JPA实体

，A和B类分别具有

joda.time.datetime

持久字段

表示

retentionDate

和

lastmodifiedDate

。A还有一个类型为

int

的

持久字段

，表示

天

。现在我想

将a.days

的数量添加到

a.retentionDate

中，然后使用

JPA标准API将其与
b.lastmodifiedDate
进行比较

实体类

@Entity
@Table(name = "A")
@Data
@JsonInclude(JsonInclude.Include.NON_NULL)
@JsonIgnoreProperties(ignoreUnknown = true)
@EqualsAndHashCode(of = "id", callSuper = false)
public class A extends AbstractBaseEntity {
    @Id
    @GeneratedValue(generator = "uuid")
    @GenericGenerator(name = "uuid", strategy = "uuid2")
    @Column(unique = true, length = 36)
    private String id;

    @Type(type = "org.jadira.usertype.dateandtime.joda.PersistentDateTime")
    @JsonDeserialize(using = DateTimeDeserializer.class)
    @JsonSerialize(using = DateTimeSerializer.class)
    private DateTime retentionDate;

    private int days;
}

@Entity
@Table(name = "B")
@Data
@JsonInclude(JsonInclude.Include.NON_NULL)
@JsonIgnoreProperties(ignoreUnknown = true)
@EqualsAndHashCode(of = "id", callSuper = false)
public class B extends AbstractBaseEntity {
    @Id
    @GeneratedValue(generator = "uuid")
    @GenericGenerator(name = "uuid", strategy = "uuid2")
    @Column(unique = true, length = 36)
    private String id;

    @Type(type = "org.jadira.usertype.dateandtime.joda.PersistentDateTime")
    @JsonDeserialize(using = DateTimeDeserializer.class)
    @JsonSerialize(using = DateTimeSerializer.class)
    private DateTime lastmodifiedDate ;

   @ManyToOne(fetch = FetchType.EAGER)
   @JoinColumn(name = "A_ID")
   private A a;
}

B实体类

@Entity
@Table(name = "A")
@Data
@JsonInclude(JsonInclude.Include.NON_NULL)
@JsonIgnoreProperties(ignoreUnknown = true)
@EqualsAndHashCode(of = "id", callSuper = false)
public class A extends AbstractBaseEntity {
    @Id
    @GeneratedValue(generator = "uuid")
    @GenericGenerator(name = "uuid", strategy = "uuid2")
    @Column(unique = true, length = 36)
    private String id;

    @Type(type = "org.jadira.usertype.dateandtime.joda.PersistentDateTime")
    @JsonDeserialize(using = DateTimeDeserializer.class)
    @JsonSerialize(using = DateTimeSerializer.class)
    private DateTime retentionDate;

    private int days;
}

@Entity
@Table(name = "B")
@Data
@JsonInclude(JsonInclude.Include.NON_NULL)
@JsonIgnoreProperties(ignoreUnknown = true)
@EqualsAndHashCode(of = "id", callSuper = false)
public class B extends AbstractBaseEntity {
    @Id
    @GeneratedValue(generator = "uuid")
    @GenericGenerator(name = "uuid", strategy = "uuid2")
    @Column(unique = true, length = 36)
    private String id;

    @Type(type = "org.jadira.usertype.dateandtime.joda.PersistentDateTime")
    @JsonDeserialize(using = DateTimeDeserializer.class)
    @JsonSerialize(using = DateTimeSerializer.class)
    private DateTime lastmodifiedDate ;

   @ManyToOne(fetch = FetchType.EAGER)
   @JoinColumn(name = "A_ID")
   private A a;
}

JPA标准查询：

CriteriaQuery<B> b = builder.createQuery(B.class);
Root<B> fromB = criteria.from(B.class); 
Expression<DateTime> lastmodifiedDate = fromB.get(B_.lastmodifiedDate);
Expression<DateTime> retentionDate = fromB.get(B_.a).get("retentionDate");
Expression<int> days = fromB.get(B_.a).get("days");
Expression<DateTime> newDate = // how to add days in retentionDate here so it became a newDate?
b.select(fromB);
b.where(builder.greaterThanOrEqualTo(newDate , lastmodifiedDate)
);

CriteriaQuery b=builder.createQuery（b.class）；
根fromB=标准from（B.class）；
表达式lastmodifiedDate=fromB.get（B_u.lastmodifiedDate）；
表达式retentionDate=fromB.get（B_u.a.get）（“retentionDate”）；
表达式days=fromB.get（B_.a）.get（“days”）；
表达式newDate=//如何在retentionDate中添加天数，使其成为newDate？
b、 选择（fromB）；
b、 其中（builder.greaterThanOrEqualTo（newDate，lastmodifiedDate）
);

请在上述查询中帮助我在retentionDate中添加天数。谢谢。
您可以使用执行数据库功能将
天数添加到
保留日期中。
我已经用做了一个例子，因为我的测试项目运行H2数据库

    ParameterExpression<String> dayUnit = builder.parameter(String.class, "dayUnit");
    Expression<DateTime> newDate = builder.function("DATEADD", DateTime.class, dayUnit, days, retentionDate);