java - 类 : . .. 中的 IllegalArgumentException 属性的 getter 方法:id

Question

我有两个类Role和Privilege，其关系为ManyToMany。将 Privilege 添加到 Role，然后调用 saveOrUpdate(role) 时，出现以下异常。

这是Role 类:

@Entity
@Table(name = "ROLES")
public class Role implements GenericDomain {

    private static final long serialVersionUID = -7620550658984151796L;

    private Long    id;
    private String  code;
    private String  name;

    private Set<User> users = new HashSet<User>(0);
    private Set<Privilege> privileges = new HashSet<Privilege>(0);

    public Role() {
    }

    public Role(String code, String name) {
        this.code = code;
        this.name = name;
    }


    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    @Column(name = "ID")
    public Long getId() { return id; }
    public void setId(Long id) { this.id = id; }

    @Column(name = "CODE", unique = true, nullable = false, length = 16)
    @NotEmpty(message= "password.required")
    @Length(min = 3, max = 16)
    public String getCode() { return code; }
    public void setCode(String code) { this.code = code; }

    @Column(name="NAME", nullable = false, length = 64)
    @NotEmpty
    @Length(min = 1, max = 32)
    public String getName() { return name; }
    public void setName(String name) { this.name = name; }

    @ManyToMany(cascade=CascadeType.ALL)
    @JoinTable(name = "ROLES_PRIVILEGES"
        , joinColumns = { @JoinColumn(name = "ROLE_ID") }
        , inverseJoinColumns = { @JoinColumn(name = "PRIVILEGE_ID") }
    )

    public Set<Privilege> getPrivileges() {
        return this.privileges;
    }
    public void setPrivileges(Set<Privilege> privileges) {
        this.privileges = privileges;
    }
    /*  overide of hascode, equals*/ 
}

这是Privilege类:

@Entity
@Table(name = "PRIVILEGES")
public class Privilege implements GenericDomain {

    private static final long serialVersionUID = 4649689934972816194L;

    private Long    id;
    private String  code;

    private Set<Role> roles = new HashSet<Role>(0);

    public Privilege() {
    }

    public Privilege(String code) {
        this.code = code;
    }

    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    @Column(name = "ID")
    public Long getId() { return id; }
    public void setId(Long id) { this.id = id; }

    @Column(name = "CODE", unique = true, nullable = false, length = 16)
    @NotEmpty(message= "password.required")
    @Length(min = 3, max = 16)
    public String getCode() { return code; }
    public void setCode(String code) { this.code = code; }

    @ManyToMany(cascade=CascadeType.REFRESH, mappedBy="privileges")
    public Set<Role> getRoles() {
        return this.roles;
    }
    public void setRoles(Set<Role> roles) {
        this.roles = roles;
    }

    /*overide equals and hascode*/
}

这是一个异常(exception):

 IllegalArgumentException in class: com.stunaz.domain.Privilege, getter method of property: id
 ....
 javax.persistence.PersistenceException: org.hibernate.PropertyAccessException: IllegalArgumentException occurred calling getter of com.stunaz.domain.Privilege.id
 ....
 java.lang.IllegalArgumentException: object is not an instance of declaring class

我的映射似乎有问题，我应该在某个地方传递一个对象，但我传递的是一个 Id。

Answer 1

在告诉用户映射出了什么问题时，Hibernate 对用户不太友好。

解决方案:

1. 调试应用
2. 为抛出 IllegalArgumentException 事件设置断点(任何地方)
3. 执行导致此情况的操作
4. 向上遍历调用堆栈并检查 Activity 堆栈变量。

使用这个过程，我找出了我的映射出了什么问题。

一般来说，从我所见，通常是在某个地方明确声明了错误的类，例如当键实际上是String等时@MapKeyClass(Wrong.class)。

或者，调用错误的 (Hibernate) API，例如 setParameter() 而不是 setParameterList():

Query query = session.getNamedQuery(queryName);  
// org.hibernate.PropertyAccessException: IllegalArgumentException occurred calling getter
query.setParameter("children", aCollectionOfChildren);
query.list();

或者，对于 Criteria API，我已经看到了:

DetachedCriteria crit = DetachedCriteria.forClass( Group.class ); crit.add( Restrictions.eq( "parent", id ) );

The getParent() method of Group returns a Group but I was attempting to compare it against a Long.