@NotFound(action=NotFoundAction.IGNORE)

引用

转载：http://blog.sina.com.cn/s/blog_7a8f609501014j34.html

使用hibernate 注解配置实体类的关联关系，在many-to-one,one-to-one关联中，一边引用自另一边的属性，如果属性值为某某的数据在数据库不存在了，hibernate默认会抛出异常。解决此问题，加上如下注解就可以了： 
@NotFound(action=NotFoundAction.IGNORE)，意思是找不到引用的外键数据时忽略，NotFound默认是exception 
下面贴出hibernate 注解的实例代码 
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@Entity 
@Table(name = "ICT_COMPUTER_LOCATION")  
public class IctComputerLocation {  
    private static final long serialVersionUID = 1L;  

    private Integer id;  
     
    private String idcNum;  

    private Integer ictBaseId;  

     
    private IctBase ictBase;  

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

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

    @Column(name = "IDC_NUM")  
    public String getIdcNum() {  
        return idcNum;  
    }  

    public void setIdcNum(String idcNum) {  
        this.idcNum = idcNum;  
    }  

    @Column(name = "ICT_BASE_ID")  
    public Integer getIctBaseId() {  
        return ictBaseId;  
    }  

    public void setIctBaseId(Integer ictBaseId) {  
        this.ictBaseId = ictBaseId;  
    }  

    @ManyToOne(fetch = FetchType.LAZY)  
    @JoinColumn(name = "ICT_BASE_ID", referencedColumnName = "ID", unique = false, nullable = false, insertable = false, updatable = false)  
    @NotFound(action=NotFoundAction.IGNORE)  
    public IctBase getIctBase() {  
        return ictBase;  
    }  

    public void setIctBase(IctBase ictBase) {  
        this.ictBase = ictBase;  
    } 

本文来自CSDN博客，转载请标明出处：http://blog.csdn.net/hardwin/archive/2009/07/08/4330779.aspx 



对象A一对多对象B，现在要查询对象A，条件中包含对象B的属性，但对象A的属性B可能为Null，这时候怎么写条件？ 
比如对象A是用户： 
Java code 
@Entity 
@Table(name = "base_staff") 
public class User { 
@Id 
@GeneratedValue 
@Column(name = "id") 
private int id; 
@Column(name = "name") 
private String name; 
@Column(name = "logname") 
private String logname; 
@Column(name = "logpass") 
private String logpass; 
@ManyToOne 
@JoinColumn(name = "gender") 
@NotFound(action=NotFoundAction.IGNORE) 
private Gender gender; 
@Column(name = "birthdate") 
private Date birthdate; 
@ManyToOne 
@JoinColumn(name = "user_status") 
@NotFound(action=NotFoundAction.IGNORE) 
private UserStatus status; 
@Column(name = "note") 
private String note; 
@ManyToMany(fetch = FetchType.EAGER) 
@JoinTable(name = "sys_user_role", 
joinColumns = { @JoinColumn(name = "user_id") }, 
inverseJoinColumns = { @JoinColumn(name = "role_id") }) 
@NotFound(action=NotFoundAction.IGNORE) 
private Set roles; 
…… 
} 
对象B是性别： 
Java code 
@Entity 
@Table(name = "code_gender") 
public class Gender { 
@Id 
@Column(name = "id") 
private int id; 
@Column(name = "name") 
private String name; 
} 
UserDao: 
Java code 
Query query = session.createQuery("from User u" + 
" where u.name like :key" + 
" or u.gender.name like :key" + 
" or u.logname like :key" + 
" or u.status.name like :key" + 
" or u.note like :key" + 
" order by u.id"); 
query.setParameter("key", "%" + key + "%"); 
query.setFirstResult(offset); 
query.setMaxResults(size); 
List list = query.list(); 
这种情况查询不到User的gender为null的数据。想要得到那些数据应该怎么些HQL呢？