基本的休眠持久性

Question

我有一個映射POJO，我需要堅持。在那個POJO中，我有另一個POJO，綁定了外鍵。
現在，當我創建一個新對象並使用Hibernate進行存儲時，Hibernate是否也會保留嵌入的POJO，或者我必須手動執行它？
基本上問題是關於「反向級聯」。

在我的情況下，這種情況不會發生，如果我沒有事先保存嵌入的POJO，我會得到一個異常。

編輯：下面是一些代碼，我省略了一些細節（設置器&獲取器）： 這是Person類，如您所見，它有一個Address類嵌入其中。

@Entity 
public class Person { 

    protected Address address; 
    protected String privateName; 
    ... 
    /* More members */ 

    @ManyToOne 
    @JoinColumn(name = "address_id", nullable = false, unique = true) 
    public Address getAddress() { 
     return this.address; 
    } 

    public void setAddress(Address address) { 
     this.address = address; 
    } 

    @Column(name = "private_name", nullable = false, length = 45) 
    public String getPrivateName() { 
     return this.privateName; 
    } 

    public void setPrivateName(String privateName) { 
     this.privateName = privateName; 
    } 
} 

這是Address類：

@JsonIgnoreProperties({ "hibernateLazyInitializer", "handler" }) 
@SuppressWarnings("serial") 
@Entity 
@Table(name = "address") 
public class Address implements java.io.Serializable { 

    private Integer id; 
    private Country country; 
    private State state; 
    private String city; 
    private String street; 
    private String number; 
    private String postcode; 
    private float longitude; 
    private float latitude; 

    public Address() { 
    } 

    public Address(Integer id, Country countries, String city, String street, 
     String number, String postcode, float longitude, float latitude) { 
    this.id = id; 
    this.country = countries; 
    this.city = city; 
    this.street = street; 
    this.number = number; 
    this.postcode = postcode; 
    this.longitude = longitude; 
    this.latitude = latitude; 
    } 

    @Id 
    @GeneratedValue(strategy = GenerationType.AUTO) 
    @Column(name = "id", unique = true, nullable = false) 
    public Integer getId() { 
    return this.id; 
    } 

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

    @ManyToOne 
    @JoinColumn(name = "state") 
    public State getState() { 
    return this.state; 
    } 

    public void setState(State state) { 
    this.state = state; 
    } 

    @ManyToOne 
    @JoinColumn(name = "country", nullable = false) 
    public Country getCountry() { 
    return this.country; 
    } 
} 

這裏是Hibernate配置我使用同春：

<bean id="dataSource" 
     class="org.springframework.jdbc.datasource.DriverManagerDataSource"> 
     <property name="driverClassName" value="org.h2.Driver" /> 
     <property name="url" value="jdbc:h2:mem:my_db;INIT=CREATE SCHEMA IF NOT EXISTS my_db;DB_CLOSE_DELAY=-1" /> 

    </bean> 

    <bean id="sessionFactory" 
     class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean"> 
     <property name="dataSource"> 
      <ref bean="dataSource" /> 
     </property> 
     <property name="packagesToScan" value="com.tra.la.bla" /> 

     <property name="hibernateProperties"> 
      <props> 
       <prop key="hibernate.dialect">org.hibernate.dialect.H2Dialect</prop> 
       <prop key="hibernate.hbm2ddl.auto">create</prop> 
       <prop key="hibernate.show_sql">true</prop> 
      </props> 
     </property> 
    </bean> 

    <bean id="transactionManager" 
     class="org.springframework.orm.hibernate3.HibernateTransactionManager"> 
     <property name="sessionFactory"> 
      <ref bean="sessionFactory" /> 
     </property> 
    </bean> 

Answer 1

沒有，一個堅持不級聯，除非你告訴Hibernate來與

@ManyToOne(cascade = CascadeType.PERSIST) 

做見http://docs.jboss.org/hibernate/core/3.6/reference/en-US/html_single/#objectstate-transitive

Answer 2

@ManyToOne(cascade = CascadeType.DETACH) 
@JoinColumn(name = "address_id", nullable = false, unique = true) 
public Address getAddress() { 
    return this.address; 
} 

也許上面的代碼解決您的問題

你可以說如何使用像上面的一些代碼一樣，hibernate作用於連接的POJO。

我希望它能幫助