hibernate:Path expected for join问题

 Os类 

public class Os { 
    private Long id; 
    private Set osFeatures = new HashSet(); 
    @Id 
    @GeneratedValue(strategy = GenerationType.AUTO) 
    @Column(name="OsId", unique = true, nullable = false, insertable = true, 
     updatable = true) 
    public Long getOsId() { 
return osId; 
     } 
      @OneToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY, mappedBy = "os") 
    public Set getOsFeatures() { 
return osFeatures; 
    } 
} 

OsFeature类： 

public class OsFeature｛ 
   
   private Long id; 
    private Os os;
@Id 
@GeneratedValue(strategy = GenerationType.AUTO) 
@Column(name = "OsFeatureId", unique = true, nullable = false,  insertable = true, updatable = true) 
public Long getId() { 
    return id; 
} 
@ManyToOne(fetch = FetchType.LAZY) 
@JoinColumn(name = "OsId", referencedColumnName = "OsId", unique = false, nullable = false, insertable = true, updatable = true) 
public Os getOs() { 
    return os; 
} 
} 

分析： 
    Os与 OsFeature之间的关联为：OneToMany(一对多)； 

需求： 
    查询Os，需要OsFeature中的某个属性作为查询条件； 

HQL语句： 
    select model from Os model join model.osFeatures osf where osf.featureString 
    like %xxxx% 

语句分析：join后面所跟的是 model.osFeatures，osFeatures为Os中的属性，而并不是OsFeature对象 

如果join后面跟的是OsFeature对象，将会报Path expected for join异常！ 

转自：http://java-primer.iteye.com/blog/573386