从SQL代码自动生成Java休眠代码

Question

Is there a tool able to generate java hibernate code starting from the sql query? (like reverse of what hibernate does, generating selects from java code) It will help me move all my queries to hibernate!

I mean if i have a select with parameters like this:

 select ta.id label, ta.nume value
    from ar 
    left outer join ta ta on idp = ta.ID
    where ta.status = 1
    and (dp = 0 OR ps = idps_)
    and status = 1
order by ta.nume;

to obtain in the end something like this:

 DetachedCriteria criteria = DetachedCriteria.forEntityName("ar");
    criteria.createAlias("ta", "ta", Criteria.LEFT_JOIN);
    criteria.add(Restrictions.eq("ta.status", 1));
    Criterion eq = Restrictions.eq("ps.id", idps_);
    Criterion isZero = Restrictions.eq("dp.id", 0);
    Criterion or = Restrictions.or(eq, isZero);
    criteria.add(or);
    criteria.add(Restrictions.eq("status", 1));
    ProjectionList projectionList = Projections.projectionList();
    projectionList.add(Projections.property("ta.id"), "value");
    projectionList.add(Projections.property("ta.nume"), "label");
    criteria.setProjection(Projections.distinct(projectionList));
    criteria.setResultTransformer(Transformers.ALIAS_TO_ENTITY_MAP);
    criteria.addOrder(Order.asc("ta.nume"));

OR something similar using maps as output...

providing to the tool the path where i store the mappings of the entities/beans with the tables (or the path to the beans, if the beans are annotated)

Answer 1

You have the HQL that is an SQL-like dialect to work with Hibernate. You use field names from entities instead of those from tables. It supports joins etc.

In fact, Criteria API has very limited support of joins (at least it was so last time I've tried to used) and I've a few times finished rewriting everything from Criteria API to HQL, so I now simply tread Criteria API as no option.

In HQL you can also use SQL functions, both in SELECT and in WHERE part, those embedded and those you've written yourself.