作者：未知 来源：月光软件站 加入时间：2005-2-28　月光软件站

• Application data class: A class defined by the application programmer primarily to hold data that will be stored in the datastore.

• Application data object: An instance of an application data class.

• PersistenceCapable class: Synonym for an application data class. This term stresses the fact that application data classes after enhancement implement JDO's PersistenceCapable interface.

• Persistence-capable class: Either a PersistenceCapable class or one of the classes from the Java standard packages that the JDO implementation supports.

• Data object: An instance of a persistence-capable class. A data object may be unmanaged, managed, transient, persistent, transactional, transient and transactional, persistent and nontransactional, or persistent and transactional. It may be stored as a first class object or as a second class object. The JDO specification uses the term JDO instance instead of data object.

• Persistent object: A data object when JDO is managing it persistently.

• Transactional object: A data object when JDO is managing it transactionally.

• Managed object: A persistent, transactional, or persistent and transactional data object.

• Transient object: Any object that JDO is not managing persistently. The JDO specification also uses the term as a synonym for an unmanaged object.

• JDO-transient: The management state that indicates that JDO is not managing the object at all. The specification calls this the transient state.

• Unmanaged object: Any object that JDO is not managing either transactionally or persistently. The term unmanaged object is a synonym for JDO-transient object.

• First class object: A data object that is stored independently in the datastore with a JDO identity. In JDO, application data objects are usually first class objects.

• Second class object: A data object that is stored in the datastore as part of a first class object. In JDO, objects of the supported system classes, such as String, Date, Long, and HashSet, are usually second class objects.

• Identity value: The value of an attribute, or a list of attributes, that uniquely identifies one persistent state in the datastore.

• JDO identity: An object that contains the identity value and can be used to obtain the corresponding application data object.

• Identity string: The string obtained from the toString method of a JDO identity object. This can be used to obtain an equivalent JDO identity object.

JDO生命周期对象的状态比较多,想要掌握JDO,必须清楚这些状态的含义.

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