org.hibernate.MappingException：无法确定类型：

Question

我将Hibernate用于项目中的所有CRUD操作。它不适用于一对多和多对一关系。它给了我下面的错误。

org.hibernate.MappingException: Could not determine type for: java.util.List, at table: College, for columns: [org.hibernate.mapping.Column(students)]

然后我又看了这个视频教程。一开始对我来说很简单。但是，我不能使其工作。现在也说

org.hibernate.MappingException: Could not determine type for: java.util.List, at table: College, for columns: [org.hibernate.mapping.Column(students)]

我在互联网上进行了一些搜索，有人告诉它Hibernate中的错误，有人说，通过添加@GenereatedValue可以清除此错误，但对我不起作用。

College.java

@Entity

public class College {

@Id

@GeneratedValue(strategy=GenerationType.AUTO)

private int collegeId;

private String collegeName;

private List<Student> students;

@OneToMany(targetEntity=Student.class, mappedBy="college", fetch=FetchType.EAGER)

public List<Student> getStudents() {

    return students;

}

public void setStudents(List<Student> students) {

    this.students = students;

}//Other gettters & setters omitted

学生.java

@Entity

public class Student {

@Id

@GeneratedValue(strategy=GenerationType.AUTO)

private int studentId;

private String studentName;

private College college;

@ManyToOne

@JoinColumn(name="collegeId")

public College getCollege() {

    return college;

}

public void setCollege(College college) {

    this.college = college;

}//Other gettters & setters omitted

Main.java：

public class Main {

private static org.hibernate.SessionFactory sessionFactory;

  public static SessionFactory getSessionFactory() {

    if (sessionFactory == null) {

      initSessionFactory();

    }

    return sessionFactory;

  }

  private static synchronized void initSessionFactory() {

    sessionFactory = new AnnotationConfiguration().configure().buildSessionFactory();

  }

Answer 1

您正在使用字段访问策略（由@Id注释确定）。将任何与JPA相关的注释放在每个字段的上方，而不是getter属性的上方@OneToMany(targetEntity=Student.class, mappedBy="college", fetch=FetchType.EAGER)private List<Student> students;