Hibernate - 查询部分字段

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第一种是使用高级查询DetachedCriteria实现，代碼如下：

String alias = "user_"; //查詢時的table別名DetachedCriteria dc = DetachedCriteria.forClass(User.class,alias);ProjectionList pList = Projections.projectionList();pList.add(Projections.property(alias + "." + "id").as("id"));pList.add(Projections.property(alias + "." + "name").as("name"));pList.add(Projections.property(alias + "." + "age").as("age"));pList.add(Projections.property(alias + "." + "sex").as("sex"));dc.setProjection(pList);dc.setResultTransformer(Transformers.aliasToBean(User.class));resultList = memberService.findByDetached(dc).size();

通過HQL语句查询

String hql = "select new Link(id,name) from Link";     Query query = session.createQuery(hql);//默认查询出来的list里存放的是一个Object对象，但是在这里list里存放的不再是默认的Object对象了，而是Link对象了List<Link> links = query.list();for(Link link : links){    String id = link.getId();    String name = link.getName();    System.out.println(id + " : " + name);}

第三种方式是通过HQL语句实现，类似SQL，方法如下：

String hql = "select id,name from Link";     Query query = session.createQuery(hql);//默认查询出来的list里存放的是一个Object数组，还需要转换成对应的javaBean。List<Object[]> links = query.list();for(Object[] link : links){    String id = link[0];    String name = link[1];    System.out.println(id + " : " + name);}