使用 @OneToMany 或 @ManyToMany 定位未映射的类：

Question

所以，你好堆栈溢出。 我在使用 hibrnate/jpa 时遇到了问题，遇到了这个异常：

org.hibernate.AnnotationException：使用@OneToMany 或@ManyToMany 针对未映射的类： com.vlad9pa.springapp.entity.User.roles[com.vlad9pa.springapp.entity.Role]

我有 3 张桌子：

1. 用户：id、用户名、密码；
2. 角色：ID、姓名；
3. user_roles:user_id、roles_id。

进口：

import javax.persistence.*;
import java.util.Set;

这是我的实体和 hibernate.cfg.xml： 用户：

@Entity
@Table(name = "users")
public class User {
private int id;
private String username;
private String password;
private Set<Role> roles;

@Id
@GeneratedValue(strategy = GenerationType.AUTO)
@Column(name = "id")
public int getId() {
    return id;
}

public void setId(int id) {
    this.id = id;
}

@Basic
@Column(name = "username")
public String getUsername() {
    return username;
}

public void setUsername(String username) {
    this.username = username;
}

@Basic
@Column(name = "password")
public String getPassword() {
    return password;
}

public void setPassword(String password) {
    this.password = password;
}

@ManyToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY, targetEntity = Role.class)
@JoinTable(name = "user_roles", joinColumns = @JoinColumn(name = "user_id"),
        inverseJoinColumns = @JoinColumn(name = "role_id"))
public Set<Role> getRoles() {
    return roles;
}

public void setRoles(Set<Role> roles) {
    this.roles = roles;
}

角色：

@Entity
@Table(name = "roles")
public class Role {

private int id;
private String name;

private Set<User> users;

@Id
@Column(name = "id")
public int getId() {
    return id;
}

public void setId(int id) {
    this.id = id;
}

@Basic
@Column(name = "name")
public String getName() {
    return name;
}

public void setName(String name) {
    this.name = name;
}



@ManyToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY, mappedBy = "roles")
public Set<User> getUsers() {
    return users;
}

public void setUsers(Set<User> users) {
    this.users = users;
}

hibernate.cfg.xml：

 <hibernate-configuration>
  <session-factory>
    <property name="hibernate.dialect">org.hibernate.dialect.PostgreSQL9Dialect</property>
    <property name="hibernate.connection.driver_class">org.postgresql.Driver</property>
    <property name="hibernate.connection.url">jdbc:postgresql://localhost:5432/e_shop</property>
    <property name="hibernate.hbm2ddl.auto">update</property>
    <property name="show_sql">false</property>
    <property name="hibernate.current_session_context_class">thread</property>
    <mapping class="com.vlad9pa.springapp.entity.Role"/>
    <mapping class="com.vlad9pa.springapp.entity.User"/>
</session-factory>

Answer 1

由于我使用了 HibernateUtil 类，因此我通过添加这一行“configuration.addAnnotatedClass(Role.class);”解决了这个问题（您应该为模型中的每个类添加此行，否则会出现“未映射错误”）

public class HibernateUtil {
        private static SessionFactory sessionFactory;
        private static ServiceRegistry serviceRegistry;
        static {
            try {
                Configuration configuration = new Configuration().configure();
                configuration.addAnnotatedClass(User.class);
                configuration.addAnnotatedClass(Role.class);

                serviceRegistry = new StandardServiceRegistryBuilder()
                        .applySettings(configuration.getProperties()).build();
                sessionFactory = configuration.buildSessionFactory(serviceRegistry);
            } catch (HibernateException e) {
                System.out.println(e);
            }
        }

        public static SessionFactory getSessionFactory(){
            return sessionFactory;
        }
}