在Hibernate中，当使用双向的一对多映射时，使用@OneToMany注释的属性会在默认情况下采用lazy fetch方式，需要使用@Fetch(FetchMode.JOIN)注释将其变为eager fetch方式。 示例代码如下：

// 父类实体 @Entity public class Parent { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) private Long id;

@OneToMany(mappedBy = "parent", fetch = FetchType.LAZY)
private List children;

// getters and setters

}

// 子类实体 @Entity public class Child { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) private Long id;

@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "parent_id")
private Parent parent;

// getters and setters

}

// 修改为eager fetch @Entity public class Parent { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) private Long id;

@OneToMany(mappedBy = "parent", fetch = FetchType.EAGER)
@Fetch(FetchMode.JOIN)
private List children;

// getters and setters

}