求教精通ejb規範的高手，關於Dependent Value Classes的疑問

wwlhp@jdon發表於2004-10-21
在ejb2.1規範的第147頁下面，
A dependent value class is a concrete class that is the value of cmp-field. A dependent value class may be a class that the Bean Provider wishes to use internally within an entity bean with container-managed persistence, and/or it may be a class that the Bean Provider chooses to expose through the remote (or local) interface of the entity bean.

A dependent value class can be the value of a cmp-field; it cannot be the value of a cmr-field.

The get accessor method for a cmp-field that corresponds to a dependent value class returns a copy of the dependent value class instance. The assignment of a dependent value class value to a cmp-field using the set accessor method causes the value to be copied to the target cmp-field.

A dependent value class must be serializable. The internal structure of a dependent value class is not described in the EJB deployment descriptor.

最讓我看不懂的就是第3段，怎麼會是複製傳的引數呢，本地客戶試圖的方法不都是pass by reference的麼？Dependent Value Class又是什麼東西呢，好像從沒有聽說過。

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