Java 如何在hibernate 5.2标准中使用和?
我有两个对象Java 如何在hibernate 5.2标准中使用和?,java,hibernate,jpa,criteria,Java,Hibernate,Jpa,Criteria,我有两个对象User和House。一个用户可以拥有多个房屋 来自House.class的注释: @Entity @Table(name="house") public class House { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) @Column(name="house_id") private int id; @ManyToOne @JoinColumn(name="user_id") private User u
User
和House
。一个用户可以拥有多个房屋
来自House.class
的注释:
@Entity
@Table(name="house")
public class House {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name="house_id")
private int id;
@ManyToOne
@JoinColumn(name="user_id")
private User user;
@Column(name="country")
private String country;
@Column(name="city")
private String city;
@Column(name="street")
private String street;
@Column(name="post_code")
private String postCode;
@Column(name="house_number")
private String houseNumber;
@Column(name="flats")
private int flats;
@Column(name="picture")
private String picture;
@Column(name="surname_first") // order names will be written in receipt
private Boolean writeSurnameFirst;
@Column(name="cut_name") // Nado ili net sokrashat imena
private Boolean cutName;
@ManyToOne
@JoinColumn(name="currency_id")
private Currency currency;
@ManyToOne
@JoinColumn(name="documentation_lang_id")
private Languages documentationLang;
@Column(name="default_house")
private Boolean defaultHouse;
我需要根据User
和列defaultHouse=true
获取House
对象
我尝试了这段代码,但我无法在其中实现User
:
tx = sess.beginTransaction();
// create criteria builder
CriteriaBuilder builder = sess.getCriteriaBuilder();
// create criteria
CriteriaQuery<House> query = builder.createQuery(House.class);
// specify criteria root
Root<House> root = query.from(House.class);
query.select(root).where(builder.equal(root.get("default_house"), true)
.and(builder.equal(root.get(House.getUser), user)));
house = sess.createQuery(query).getSingleResult();
tx.commit();
tx=sess.beginTransaction();
//创建标准生成器
CriteriaBuilder=sess.getCriteriaBuilder();
//创建标准
CriteriaQuery=builder.createQuery(House.class);
//指定条件根
Root=query.from(House.class);
query.select(root).where(builder.equal(root.get(“default_house”),true)
和(builder.equal(root.get(House.getUser),user));
house=sess.createQuery(query.getSingleResult();
tx.commit();
事实上,builder.and()
接受两个参数,这两个参数是SQL中与和关键字连接的两个限制,并且builder.and()
应该在builder.where()方法中使用
更改以下代码:
query.select(root).where(builder.equal(root.get("default_house"), true)
.and(builder.equal(root.get(House.getUser), user)));
像这样:
query.select(root).where(builder.and(builder.equal(root.get("default_house"), true), builder.equal(root.get(House.getUser), user))));
有关更多详细信息和示例,请参阅
注意:
Hibernate
关注的是对象而不是表,当我们使用其模块(如Criteria
时,我们在对象中使用属性名称,而不是DB列名称 在CriteriaBuilder方法中,必须使用如下实体字段名称:
builder.equal(root.get("defaultHouse"), true)
而不是数据库列名:
builder.equal(root.get("default_house"), true)
我附上了我的例子:
CriteriaBuilder builder = session.getCriteriaBuilder();
CriteriaQuery<Eje> query = builder.createQuery(Eje.class);
Root<Eje> productRoot = query.from(Eje.class);
query.select(productRoot)
.where(builder.and(builder.equal(productRoot.get("id"), 1), builder.equal(productRoot.get(Eje_.factorCriticos).get(FactorCritico_.id), 1)));
result =(List<T>) session.createQuery(query).getResultList();
CriteriaBuilder=session.getCriteriaBuilder();
CriteriaQuery=builder.createQuery(Eje.class);
Root productRoot=query.from(Eje.class);
query.select(productRoot)
其中(builder.and(builder.equal(productRoot.get(“id”),1),builder.equal(productRoot.get(Eje.factorCriticos.get(FactorCritico.id),1));
result=(List)session.createQuery(query.getResultList();