Java版 - Questions on EJB3 Persistence/Hibernate |
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T*****e
发帖数: 361 | 1 I am using EJB3 Persistence through Hibernate. My entity classes are
annotated and packed in a jar file. It works.
I have two questions.
The first one is quite simple. Can I use simple classes (other than
entities) in EJB/QL? Example:
List addresses = entityManager.createNativeQuery(
"select u.address from user as u").listResults();
The above query seems fine. But how can I use the result? I've tried:
String address = (String) addresses.get(i);
but it doesnot' work.
The second questio | T*****e
发帖数: 361 | 2 呵呵，每人理我，只好自己顶一下。
对于第二个问题：
最初我发帖的时候，并未从google上找到有用的信息。今天把
Hiberbate的源代码找出来看了看，发现Hibernate居然试图
把我定义的Map转换为java.sql.Blob，这
才导致了Exception。看上去更像Hibernate的问题，而不是
我自己的。
重新上google找了找，还真有人提到这个问题，说是Hibernate
的@Lob不支持Map interface，因为从interface本身不能判
断出是否Serializable。也有道理，不过也太不方便了。
刚才把我的Map都替换成HashMap
String>，试了一下，果然就没有问题了。
嗯，Open Source的一个好处就是，实在没有办法的时候，总
还可以指望有代码可以看看。上次用TrueZip的一个函数来实
现Zip Entry的直接读写（没有解压、压缩），让Supervisor
很是满意，算是挣了点credit。
那天有空再折腾一下第一个问题，搞明白之后再回来汇报一下。
【在 T*****e 的大作中提到】
: I am using EJB3 Persistence through Hibernate. My entity classes are
: annotated and packed in a jar file. It works.
: I have two questions.
: The first one is quite simple. Can I use simple classes (other than
: entities) in EJB/QL? Example:
: List addresses = entityManager.createNativeQuery(
: "select u.address from user as u").listResults();
: The above query seems fine. But how can I use the result? I've tried:
: String address = (String) addresses.get(i);
: but it doesnot' work.
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