Java 在 Hibernate 中通过 ID 获取对象
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Get object by ID in Hibernate
提问by MyTitle
I noticed that our senior developer uses following code for retrieving entity by ID:
我注意到我们的高级开发人员使用以下代码通过 ID 检索实体：
@Override
public Source get(Long id) {
Session session = getSession();
if( session == null )
session = sessionFactory.openSession();
final Source source = (Source)session.load(Source.class, id);
Hibernate.initialize(source);
return source;
}
What is benefit of this code?
这段代码有什么好处？
Why not simply writing
为什么不简单地写
return (Soruce) getSession().get(Source.class, id);
回答by ben75
Those 2 pieces of code aren't equivalent.
这两段代码是不等价的。
session.load(Source.class, id);
will throw an exceptionif there is no Sourceentity with the identifier id.
如果没有带有标识符的实体，将抛出异常。Sourceid
getSession().get(Source.class, id);
will return nullif there is no Sourceentity with the identifier id.
如果没有带有标识符的实体，则返回 null。Sourceid
