已经有很多很棒的答案，但我使用@Pankaj Garg 的答案（使用 Spring Specification API）专门实现了这个。我在回答中添加了一些用例
- 4 个参数，可能为空，也可能不为空。
- 来自存储库的分页响应。
- 按嵌套对象中的字段过滤。
- 按特定字段排序。
首先我创建了几个实体，特别是Ticket、Movie 和Customer。这里没什么特别的：
import lombok.AllArgsConstructor;
import lombok.Builder;
import lombok.Data;
import lombok.NoArgsConstructor;
import javax.persistence.*;
import javax.validation.constraints.NotNull;
import javax.validation.constraints.Size;
import java.io.Serializable;
import java.math.BigDecimal;
import java.util.Date;
import java.util.UUID;
@Entity
@Table(name = "ticket", schema = "public")
@Data
@NoArgsConstructor
@AllArgsConstructor
@Builder(toBuilder = true)
public class Ticket implements Serializable {
@Id
@Basic(optional = false)
@NotNull
@Column(name = "id", nullable = false)
private UUID id;
@JoinColumn(name = "movie_id", referencedColumnName = "id", nullable = false)
@ManyToOne(fetch = FetchType.EAGER)
private Movie movie;
@JoinColumn(name = "customer_id", referencedColumnName = "id", nullable = false)
@ManyToOne(fetch = FetchType.EAGER)
private Customer customer;
@Column(name = "booking_date")
@Temporal(TemporalType.TIMESTAMP)
private Date bookingDate;
}
电影：
import lombok.AllArgsConstructor;
import lombok.Builder;
import lombok.Data;
import lombok.NoArgsConstructor;
import javax.persistence.*;
import javax.validation.constraints.NotNull;
import javax.validation.constraints.Size;
import java.io.Serializable;
@Entity
@Table(name = "movie", schema = "public")
@Data
@NoArgsConstructor
@AllArgsConstructor
@Builder(toBuilder = true)
public class Movie implements Serializable {
@Id
@Basic(optional = false)
@NotNull
@Column(name = "id", nullable = false)
private UUID id;
@Basic(optional = false)
@NotNull
@Size(max = 100)
@Column(name = "movie_name", nullable = false, length = 100)
private String movieName;
}
客户：
import lombok.AllArgsConstructor;
import lombok.Builder;
import lombok.Data;
import lombok.NoArgsConstructor;
import javax.persistence.*;
import javax.validation.constraints.NotNull;
import javax.validation.constraints.Size;
import java.io.Serializable;
@Entity
@Table(name = "customer", schema = "public")
@Data
@NoArgsConstructor
@AllArgsConstructor
@Builder(toBuilder = true)
public class Customer implements Serializable {
@Id
@Basic(optional = false)
@NotNull
@Column(name = "id", nullable = false)
private UUID id;
@Basic(optional = false)
@NotNull
@Size(max = 100)
@Column(name = "full_name", nullable = false, length = 100)
private String fullName;
}
然后我创建一个类，其中包含我希望过滤的参数的字段：
import lombok.AllArgsConstructor;
import lombok.Data;
import java.util.Date;
import java.util.UUID;
@Data
@AllArgsConstructor
public class TicketFilterParam {
private UUID movieId;
private UUID customerId;
private Date start;
private Date end;
}
接下来我创建一个类来根据过滤器参数生成Specification。请注意访问嵌套对象的方式，以及将排序添加到查询的方式。
import org.springframework.data.jpa.domain.Specification;
import javax.persistence.criteria.Predicate;
import java.util.ArrayList;
import java.util.List;
import java.util.UUID;
public class TicketSpecifications {
public static Specification<Ticket> getFilteredTickets(TicketFilterParam params) {
return (root, criteriaQuery, criteriaBuilder) -> {
List<Predicate> predicates = new ArrayList<>();
if (params.getMovieId() != null) {
predicates.add(criteriaBuilder.equal(root.get("movie").<UUID> get("id"), params.getMarketerId()));
}
if (params.getCustomerId() != null) {
predicates.add(criteriaBuilder.equal(root.get("customer").<UUID> get("id"), params.getDepotId()));
}
if (params.getStart() != null && params.getEnd() != null) {
predicates.add(criteriaBuilder.between(root.get("bookingDate"), params.getStart(), params.getEnd()));
}
criteriaQuery.orderBy(criteriaBuilder.desc(root.get("bookingDate")));
return criteriaBuilder.and(predicates.toArray(new Predicate[0]));
};
}
}
接下来我定义存储库接口。这不仅有JpaRepository，还有JpaSpecificationExecutor：
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.JpaSpecificationExecutor;
import org.springframework.stereotype.Repository;
@Repository
public interface TicketRepository extends JpaRepository<Ticket, UUID>, JpaSpecificationExecutor<Ticket> {
}
最后，在某个服务类中，我得到如下结果：
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.PageRequest;
import org.springframework.data.jpa.domain.Specification;
import org.springframework.stereotype.Service;
@Service
public class TicketService {
@Autowired
private TicketRepository ticketRepository;
public Page<Ticket> getTickets(TicketFilterParam params, PageRequest pageRequest) {
Specification<Ticket> specification = TicketSpecifications.getFilteredTickets(params);
return ticketRepository.findAll(specification, pageRequest);
}
}
PageRequest 和TicketFilterParam 可能会从休息端点上的某些参数和值中获得。