相关疑难解决方法(0)

有什么区别:

@Entity
public class Company {

    @OneToMany(cascade = CascadeType.ALL , fetch = FetchType.LAZY)
    @JoinColumn(name = "companyIdRef", referencedColumnName = "companyId")
    private List<Branch> branches;
    ...
}

和

@Entity
public class Company {

    @OneToMany(cascade = CascadeType.ALL , fetch = FetchType.LAZY, mappedBy = "companyIdRef")
    private List<Branch> branches;
    ...
}

hibernate映射中的默认提取类型是什么？

探索之后我才知道的是:

• 一对一,它是渴望.
• 对于一对多它是懒惰的.

但是在Eclipse中测试之后,它渴望所有人.

这取决于我使用的是JPA还是Hibernate？

我正在使用Jackson将我的JPA模型序列化为JSON.

我有以下课程:

import com.fasterxml.jackson.annotation.*;
import javax.persistence.*;
import java.util.Set;

@JsonInclude(JsonInclude.Include.NON_NULL)
@JsonIgnoreProperties(ignoreUnknown = true)
@JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class)
@Entity
public class Parent {
  @Id
  @GeneratedValue(strategy = GenerationType.IDENTITY)
  private Long id;
  private String name;

  @JsonManagedReference
  @OneToMany(mappedBy = "parent", cascade = CascadeType.ALL, fetch = FetchType.EAGER)
  private Set<Child> children;

  //Getters and setters
}

和

import com.fasterxml.jackson.annotation.*;
import javax.persistence.*;
import java.util.HashSet;
import java.util.Set;

@JsonInclude(JsonInclude.Include.NON_NULL)
@JsonIgnoreProperties(ignoreUnknown = true)
@JsonIdentityInfo(generator = ObjectIdGenerators.IntSequenceGenerator.class)
@Entity
public class Child {
  @Id
  @GeneratedValue(strategy = GenerationType.IDENTITY)
  private Long id;
  private String name;

  @JsonBackReference
  @ManyToOne …