有没有办法用JPA/休眠方式滚动结果? [英] Is there are way to scroll results with JPA/hibernate?
问题描述
我在Toplink中发现了一些提示
I found some hint in Toplink
Query query = em.createQuery("SELECT e FROM Employee e ORDER BY e.lastName ASC, e.firstName ASC");
query.setHint("eclipselink.cursor.scrollable", true);
ScrollableCursor scrollableCursor = (ScrollableCursor)query.getSingleResult();
List<Employee> emps = scrollableCursor.next(10);
是否有jpa/hibernate替代方案?
is there are jpa/hibernate alternative?
推荐答案
据我所知,JPA中没有针对此的标准.
To my knowledge, there is nothing standard in JPA for that.
使用Hibernate,我知道的最接近的替代方法是Query
/
With Hibernate, the closest alternative I'm aware of would be the Query
/ ScrollableResults
APIs. From the documentation:
10.4. 1.6.可滚动迭代
如果JDBC驱动程序支持 可滚动的ResultSets,查询 界面可用于获取 ScrollableResults对象,它允许 灵活的查询导航 结果.
10.4.1.6. Scrollable iteration
If your JDBC driver supports scrollable ResultSets, the Query interface can be used to obtain a ScrollableResults object that allows flexible navigation of the query results.
Query q = sess.createQuery("select cat.name, cat from DomesticCat cat " +
"order by cat.name");
ScrollableResults cats = q.scroll();
if ( cats.first() ) {
// find the first name on each page of an alphabetical list of cats by name
firstNamesOfPages = new ArrayList();
do {
String name = cats.getString(0);
firstNamesOfPages.add(name);
}
while ( cats.scroll(PAGE_SIZE) );
// Now get the first page of cats
pageOfCats = new ArrayList();
cats.beforeFirst();
int i=0;
while( ( PAGE_SIZE > i++ ) && cats.next() ) pageOfCats.add( cats.get(1) );
}
cats.close()
请注意,打开的数据库连接
并且为此需要光标
功能.使用
setMaxResult()
/setFirstResult()
(如果您)
需要离线分页功能.
Note that an open database connection
and cursor is required for this
functionality. Use
setMaxResult()
/setFirstResult()
if you
need offline pagination functionality.
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