使用ManyToMany的MappingException

Question

我正在使用JBoss AS 7和IDEA 11。当我尝试部署我的应用程序时，我遇到了这样的问题：

我的应用程序中有两个实体：

首先：

@Entity
@Table(name="users")
public class User extends AbstractEntity {

    private static final long serialVersionUID = -3839809902040717567L;

    @Column(name="email") private String email;
    @Column(name="first_name") private String firstName;
    @Column(name="last_name") private String lastName;
    @Column(name="middle_name") private String middleName;
    @Column(name="password") private String password;
    @Column(name="client_id") private int clientId;
    @Column(name="user_name") private String userName;
    private List<Role> roles;

    public User() {
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public String getFirstName() {
        return firstName;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    public String getMiddleName() {
        return middleName;
    }

    public void setMiddleName(String middleName) {
        this.middleName = middleName;
    }

    public String getPassword() {
        return password;
    }

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

    public int getClientId() {
        return clientId;
    }

    public void setClientId(int clientId) {
        this.clientId = clientId;
    }

    public String getUserName() {
        return userName;
    }

    public void setUserName(String userName) {
        this.userName = userName;
    }

    @ManyToMany(cascade = {CascadeType.ALL})
    @JoinTable(name = "users_roles",
            joinColumns = {@JoinColumn(name = "user_id")},
            inverseJoinColumns = @JoinColumn(name = "role_id"))
    public List<Role> getRoles() {
        return roles;
    }

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

第二：

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

    private static final long serialVersionUID = -192049947690313026L;

    @Column(name="ad_name") private String  adName;
    @Column(name="description") private String description;
    @Column(name="name") private String name;
    @OneToMany(mappedBy = "roles") private List<RolesPermissions> rolesPermissions;
    @ManyToMany(mappedBy = "roles") List<User> users;


    public String getAdName() {
        return adName;
    }

    public void setAdName(String adName) {
        this.adName = adName;
    }

    public String getDescription() {
        return description;
    }

    public void setDescription(String description) {
        this.description = description;
    }

    public String getName() {
        return name;
    }

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

    public List<User> getUsers() {
        return users;
    }

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

    public List<RolesPermissions> getRolesPermissions() {
        return rolesPermissions;
    }

    public void setRolesPermissions(List<RolesPermissions> rolesPermissions) {
        this.rolesPermissions = rolesPermissions;
    }

}

他们有ManyToMany关系。

在部署时，我遇到了这样的异常：

Caused by: org.hibernate.MappingException: Could not determine type for: java.util.List, at table: users, for columns: [org.hibernate.mapping.Column(roles)]
    at org.hibernate.mapping.SimpleValue.getType(SimpleValue.java:304)
    at org.hibernate.mapping.SimpleValue.isValid(SimpleValue.java:288)
    at org.hibernate.mapping.Property.isValid(Property.java:216)

可能的原因是什么？

P.S. AbstractEntity为mappedsuperclass，并且具有带有@Id注释的字段。

Answer 1

您的User实体没有注释roles关系。@ManyToMany注释应该可以做到这一点。

正如@Perception指出的那样，您可能还希望在roles上分隔连接表，例如：

@JoinTable(name="USER_ROLE", joinColumns= @JoinColumn(name="EMP_ID"), inverseJoinColums = @JoinColumn(name="ROLE_ID"))

编辑:只有在使用现有模式或者默认的表名和列名不适合您的情况下，此注释才有意义。如果您让Hibernate生成表，则可以安全地省略@JoinTable注释。